boiler safety valve discharge piping price

2023-05-21 21:22:12

Temperature/pressure-relief or TPR valves are safety devices installed on water heating appliances, such as boilers and domestic water supply heaters. TPRs are designed to automatically release water in the event that pressure or temperature in the water tank exceeds safe levels.

If temperature sensors and safety devices such as TPRs malfunction, water in the system may become superheated (exceed the boiling point). Once the tank ruptures and water is exposed to the atmosphere, it will expand into steam almost instantly and occupy approximately 1,600 times its original volume. This process can propel a heating tank like a rocket through multiple floors, causing personal injury and extensive property damage.

Water-heating appliance explosions are rare due to the fact that they require a simultaneous combination of unusual conditions and failure of redundant safety components. These conditions only result from extreme negligence and the use of outdated or malfunctioning equipment.

The TPR valve will activate if either water temperature (measured in degrees Fahrenheit) or pressure (measured in pounds per square inch [PSI]) exceed safe levels. The valve should be connected to a discharge pipe (also called a drain line) that runs down the length of the water heater tank. This pipe is responsible for routing hot water released from the TPR to a proper discharge location.

It is critical that discharge pipes meet the following requirements, which can be found in InterNACHI’s Water Heater Discharge Piping mini-course, at www.nachi.org/education. A discharge pipe should:

discharge to a termination point that is readily observable by occupants, because discharge indicates that something is wrong, and to prevent unobserved termination capping.

A properly functioning TPR valve will eject a powerful jet of hot water from the discharge pipe when fully activated, not a gentle leak. A leaky TPR valve is an indication that it needs to be replaced. In the rare case that the TPR valve does activate, the homeowner should immediately shut off the water and contact a qualified plumber for assistance and repair.

Inspectors should recommend that homeowners test TPR valves monthly, although inspectors should never do this themselves. The inspector should demonstrate to the homeowner how the main water supply can be shut off, and explain that it can be located at the home"s main water supply valve, or at the water supply shut-off for the appliance on which the TPR is mounted.

The pressure at which a TPR valve will activate is printed on a data plate located beneath the test lever. This amount should not exceed the working pressure limit marked on the data plate of the water-heating appliance it serves.

TPR valves with missing data plates should be replaced.Although a TPR valve might never become activated, it is an essential safety component on boilers and domestic water heaters. Guidelines concerning these valves and their discharge pipes reflect real hazards that every homeowner and home inspector should take seriously. More information about this subject can be found in InterNACHI"s Water Heater Discharge Piping mini-course, InterNACHI"s Plumbing Inspection course or by contacting a qualified plumber.

boiler safety valve discharge piping price

A series of anomalies occurred in the boiler room that evening. The steel compression tank for the hydronic loop flooded, leaving no room for expansion. Water will expand at 3% of its volume when heated from room temperature to 180° F. When the burner fired, the expansion of the water increased the system pressure within the boiler. The malfunctioning operating control did not shut off the burner at the set point which caused the relief valve to open.

The brass relief valve discharge was installed with copper tubing piped solid to a 90° ell on the floor and the tubing further extended to the floor drain. The combination of hot water and steam from the boiler caused the discharge copper tubing to expand, using the relief valve as a fulcrum. The expansion of the copper discharge tubing pressing against the floor was enough to crack the brass relief valve, flooding the boiler room. The damage was not discovered until the next morning, several hours after the leak occurred. Thousands of dollars in damage was sustained and luckily no one was injured.

Each boiler requires some sort of pressure relieving device. They are referred to as either a safety, relief or safety relief valve. While these names are often thought of as interchangeable, there are subtle differences between them. According to the National Board of Boiler and Pressure Vessel Inspectors, the following are the definitions of each:

• Safety valve— This device is typically used for steam or vapor service. It operates automatically with a full-opening pop action and recloses when the pressure drops to a value consistent with the blowdown requirements prescribed by the applicable governing code or standard.

• Relief valve— This device is used for liquid service. It operates automatically by opening farther as the pressure increases beyond the initial opening pressure and recloses when the pressure drops below the opening pressure.

• Safety relief valve— This device includes the operating characteristics of both a safety valve and a relief valve and may be used in either application.

• Temperature and pressure safety relief valve— This device is typically used on potable water heaters. In addition to its pressure-relief function, it also includes a temperature-sensing element which causes the device to open at a predetermined temperature regardless of pressure. The set temperature on these devices is usually 210°.

• Relief valve piping— The boiler contractor installed a bushing on the outlet of the safety relief valve. Instead of 1 1/2-in. pipe, the installer used 3/4-in. pipe. When asked about it, he answered that he did not have any 1 1/2-in. pipe but had plenty of 3/4-in. pipe. I explained and then had to show the disbelieving contractor the code that states that the relief valve discharge piping has to be the same diameter as the relief valve outlet (see 2012 International Mechanical Code, 1006.6). By reducing the discharge pipe size, the relieving capacity of the safety valve may not be adequate to properly relieve the pressure inside the boiler, causing a dangerous situation.

The code also states that the discharge material shall be of rigid pipe that is approved for the temperature of the system. The inlet pipe size shall be full diameter of the pipe inlet for the relief valve. Some manufacturers suggest using black iron pipe rather than copper tubing. If using copper, it should have an air space that allows expansion should the relief valve open to avoid the accident that I referenced above. The discharge piping has to be supported and the weight of the piping should not be on the safety relief valve. Valves are not permitted in the inlet piping to or discharge piping from the relief valve. If you are using copper tubing on discharge piping, verify that there is room for expansion.

• Installation— Read the manufacturer’s installation manual as each may have different requirements. For instance, Conbraco requires that the discharge piping must terminate with a plain end and use a material that can handle temperatures of 375° or greater. This will preclude PVC or CPVC pipe for the discharge piping. The instruction manual for its model 12-14 steam relief valve stipulates that you cannot use a pipe wrench to install it. That would be good to know.

I once visited Boiler Utopia as the floor was clean and waxed. All the pipes were covered and exposed pipes were painted. There were large stickers detailing what was inside each pipe as well as directional arrows. Nothing was stacked next to the boilers. Yellow caution lines were painted on the floor around each boiler. I was in heaven. As I walked around the rear of the boiler, something clicked and triggered a warning bell. The discharge of the relief valve piping was about 6 in. from the floor but instead of a plain or angled cut end, the pipe had a threaded pipe cap on the termination. I asked the maintenance person about it and he said that the valve was leaking all over his newly waxed floor and this was the only way he could stop it. When I said that the discharge pipe should not have been threaded, he explained that it was not threaded and he had to take it to the local hardware store to thread it. I informed him that the cap had to be removed. We cut the pipe on an angle to prevent this.

• Steam boiler— Most manufacturers recommend a drip pan ell on the discharge of the steam boiler relief valve to eliminate the weight of the discharge piping on the relief valve. Some codes require the discharge to be vented outdoors.

• Testing— I will ask the attendees in my classes, “How often do you test the relief valves?” Most do not make eye contact and when I follow up with, “Why are they not tested?” I often hear that opening the relief valve will cause it to leak. I suggest that you refer to each manufacturer’s directions for testing. For instance, one will recommend once a year while another recommends twice a year. One manufacturer says, “Safety/relief valves should be operated only often enough to assure they are in good working order.” I am not sure what that even means. You want to also verify the proper test procedure as some will only want the relief valve tested when the boiler is at 75% of the rated pressure or higher of the relief valve.

boiler safety valve discharge piping price

I wanted to see if someone with more experience in steam safety valve piping design could point me in the right direction. I do MEP work and have for 25 years. Typically we route the discharge of a steam safety directly to the exterior of a building without headering them together. I have had two projects lately where the mechanical contractor has requested headering the discharges due to limited availability of discharge locations.

I have done the research to the point of absolute mind numbness on headered vent piping. Can someone point to the relevent codes, design guides, etc.. that would address headered steam safety relief discharge piping? The issue I am having is what is applicable to 1) steam and 2) headered discharge piping. I can find a thousand references for how to size reliefs (which I don"t need) but nothing that clearly defines a path for a safe design.

A little background on one of them. It is an existing site where the discharge of the relif valves on the downstream side of a PRV station is sized for 10" and is routed about 150 feet to atmosphere. Set pressure on these is 70 pisg. There are also two steam-to-steam generators that have shell side relief valves connected to this system. These two generators have a shell pressure of 15 psig and the reliefs are set at 35 psig. The contractor wants to add two more steam-to-steam generators to this arrangement with the same set pressures. My gut is that everything will be okay becuase the shell side of the generators is separated from the steam leaving the prv (which is on the tube side) so actuation of all safeties at the same time is improbable. For this to occur the PRV and control valve on the inlet of the generators would have to fail simultaneously. Gut feelings, however, don"t save you when things blow apart.

boiler safety valve discharge piping price

Discharge pipe shall discharge independently by gravity through an air gap into the drainage system or outside of the building with the end of the pipe not exceeding 2 feet (610 mm) and not less than 6 inches (152 mm) above the ground and pointing downwards.

boiler safety valve discharge piping price

ASME Section IV Safety Relief Valve for protection of small hot water heating boilers and hydronic heating systems. Made from proven ASTM grade Brass and Bronze materials with decorative chrome finish.

ASME Section IV capacity certified bronze safety relief valve for protection of hot water heating boilers, systems and similar equipment. It can be Pre-set to any pressure ranging between 20 to 80 psig (1.4 to 5.5 bar) at 250�F (121�C) max

ASME Section IV capacity certified bronze safety relief valve for protection of hot water heating boilers, systems and similar equipment. It can be pre-set to any pressure ranging from 15 to 160 psig (1 to 11 bar) at 250�F (121�C) max.

ASME Section VIII design certified Safety Valve to protect portable steam vessel applications such as autoclaves, sterilizers and pressure cookers against excess pressure build-up. Made from proven ASTMgrade Brass with optional decorative chrome finish.

ASME Section I & VIII air and steam capacity certified safety valve for overpressure protection of steam power boilers, deaerators, accumulators, pressure reducing stations and pressure piping systems.

Medium capacity safety valves protect ASME Section IV low pressure steam heatingboilers. Cast bronze, full nozzle design features PTFE faced elastomer soft seatingfor dependable operation.

The Apollo� 13 Series bronze low pressure steam safety valve is designed to meet ASME Section IV code requirements for protection of steam heating boilers, systems and similar equipment.

The Apollo� 14 Series is a 100% American Made Bronze Safety Relief Valve for protection of steam boilers, low pressure, high volume blowers, compressors and vacuum systems.

ASME Section I and VIII capacity certified safety valve for overpressure protection of steam power boilers, systems, pressure vessels, piping and similar equipment. Suitable for steam, air and non-hazardous gases.

ASME Section I/Section VIII capacity certified safety valve for overpressure protection of steam power boilers, steam and air systems, pressure vessels, piping and similar equipment. Compact and economic design ideal for OEM applications.

ASME Section VIII capacity certified safety relief valve for overpressure protection of steam, air/gas and liquid systems, pressure vessels, piping and similar equipment.

Drip Pan Elbows connect to the safety valveoutlet and direct steam discharge into the discharge piping, allowing condensate to drain away. Isolates the valve from piping stresses.Highly recommended in steam service.

High volume air relief valves designed for low pressure air and gas service. Ruggedbronze construction features elastomer soft seating and TFE coated discs fordependable operation.

ASME Section VIII capacity certified relief valve foroverpressure protection of compressors, intercoolers,dryers, receivers, control and instrument air lines andsimilar equipment.

ASME Section VIII capacity certified safety relief valve for overpressure protection of steam, air/gas and liquid systems, pressure vessels, piping and similar equipment.

High flow vacuum relief valves feature one piece cast bronze bodies, Teflon coated discs and elastomer soft seating provide accurate and dependable operation. Ideal for use with high volume vacuum systems, bulk hauling tanks and trailers, powdered solids/bulk handling and pneumatic conveying equipment.

The Apollo� Model VR Vacuum Relief valve is designed to automatically vent a system should avacuum occur. It prevents siphoning of water from the system and/or tank collapse.

boiler safety valve discharge piping price

This article describes the requirements for a discharge tube or drain line on temperature & pressure relief valves used on any appliance that heats water. These include hydronic heating boilers (hot water boilers), steam boilers, and all types of water heaters, both those that use a water storage tank or cylinder and those that heat water on demand such as tankless water heaters.

Here we describe the installation specifications for TPR valve drain line piping and we include an extensive list of discharge tube installation or condition defects, most of which are unsafe. All of them are improper.

The Temperature & Pressure Relief Valve or TPR Valve on any heated appliance that contains water, such as a heating boiler, hot water tank, water heater, water cylinder, must have a drain line or discharge tube properly installed, routed, and made of proper materials. The purpose of this drain line is to discharge potentially hot scalding water to a safe location so that a bystander is not scalded.

At left we see a typical TPR valve installation (by the author) including the vertical 3/4" copper drain piping that will discharge any T&P valve spillage to the floor.

An unsafe TPR drain line installation is shown at the top of this page. Only a complete fool would do what we found on this boiler. To "stop" an annoying boiler drip at the pressure temperature relief valve, the mechanic installed a short length of pipe capped by a drain valve which he could simply shut. This might have been installed on a system for other reasons, such as connecting a hose to permit easy draining of pressure off of the boiler through the TP valve.

But it is in all events dangerous, illegal, and plain stupid to ever install a shutoff valve or any other sort of "cap" on a pressure/temperature relief valve.

But how dangerous is it to omit a discharge drain tube on a TPR valve? The possibility of a scalding burn is obvious but do these accidents actually happen?

Noticing that a TPR discharge tube was missing on a heating boiler during a home inspection I [DF] pointed out this safety hazard to my client while the real estate agent nearby frowned at my "old maid" trouble-making personality.

My client burst into tears. Sobbing she told me that she was grateful that inspectors would routinely point-out this hazard. Her son, playing with friends in the basement, lost an eye when he and a pal opened the discharge lever on a heating boiler, scalding his face and ruining his left eye forever.

Less dramatic but scary, at a different inspection I found that a string tied through a small hole in the end of the TPR valve"s test lever. The string was routed up towards the ceiling, over a horizontal plumbing line and back down to a termination in a nice knot a few feet above the floor.

This interesting TPR test lever addition was explained by the building owner. His son and friends liked to play steam boat. It was fun to pull the string, pretending it was a steam boat whistle, and to see the burst of steamy hot water emerge from the end of the discharge line.

TPR Valve Discharge tube is installed: Check that the Temperature/Pressure relief valve has a discharge tube properly installed. The drain line must be connected to the discharge outlet of the T&P valve to "avoid water damage and scalding injury." (Watts 2011)

Our photo (left) shows an oil fired water heater with a T&P valve that has no discharge tube installed. There are of course other operating problems with this water heater as the photo makes clear.

TPR Valve Discharge tube blocked: Check that the discharge is not blocked by anything whatsoever. Our page top photo shows a shutoff drain valve installed at the end of a short T&P valve discharge line.

The risk is that the valve is no longer leaking not because a proper repair has been made, but because the valve has become clogged and blocked by mineral salts left behind by the evaporating hot water - leaving the installation dangerous and risking a BLEVE - explosion.

This is an unsafe condition as the operation of the temperature or pressure relief valve may be interfered with by the insulation and also because the valve cannot be inspected for evidence of leaks or failure.

Similarly, discharging a relief valve leakage or drip to a location where the leak or drip cannot be observed is a dangerous practice because the leak can go unnoticed, causing failure to recognize an unsafe condition.

TPR Valve Discharge Tube Piped "UP": the drain line must never be piped upwards in any of its course. The hazard is that the drain can become blocked or that a small drip, representing an unsafe condition at the T&P valve, may be hidden as the water simply accumulates in the bend of the trap or upwards piped section.

TPR Valve Discharge Tube Crimped, Plugged, or Reduced: the drain line may not be bent, crimped, nor plugged by any material. The diameter of the drain line may not be reduced to a size smaller than the opening of the T&P valve that it serves. Some jurisdictions may limit the number of elbows or bends permitted in the piping.

The photos above illustrates this unsafe installation practice: a 1/2" copper tube has been installed through a reducing fitting into the mouth or piping of a 3/4" diameter TPR valve.

Below the reducer from 3/4" to 1/2" was installed at the TPR valve opening. At above right a reducing elbow was used to shrink the 3/4" horizontal T&P drain line (from the TPR valve mouth) to 1/2" for the vertical run to the floor. Both of these installations are improper and unsafe.

TPR Valve Discharge Tube Active Leaking: above we show a wet floor area as well as the corroded end of the T&P discharge tube in our first photo: this relief valve is actively leaking. In this case investigation showed that the valve itself had failed - we replaced it.

TPR Valve Drain line Drip Marks: any drip stains on the floor below the valve discharge tube (second photo above ) also indicate a history of leaks at the T&P valve. Without further investigation we don"t know if this problem has been repaired or if it is simply intermittent.

TPR Valve Discharge Tube Opening is Wet: If there is corrosion on the end of the discharge tube or if you see drip stains on the floor below the drain pipe, even if the floor is dry you should always test for active or recent spillage at the relief valve. It"s possible that water on the floor has dried (on its own or with some help before a building inspection).

But if there has been recent spillage at the TPR valve the interior of the end of the discharge tube can confirm that. Using your finger, feel the inside of the tip of the discharge tube and check for water - it should be dry.

As the two photos show below, even though the floor was dry below this T&P drain line, the interior of the drain was wet - there was active leaking (or someone had recently opened the valve).

TPR Valve Discharge Tube Materials: the drain line material requirements vary by jurisdiction; some areas permit both plastic as well as copper or galvanized steel piping. But where plastic drain line materials are used, the temperature rating of the plastic must be above the highest temperature that might be produced by the heating appliance to which the T&P valve is connected.

TPR Valve Discharge Tube Termination Fittings: the end of the discharge or drain line tube should not be threaded nor fitted with any device that would permit attachment of a cap, plug, or valve that could close off the line.

TPR Valve Discharge Tube Termination Location: The water that may be discharged from a T&P valve must be conducted to a safe place of disposal. This may be a floor drain (recommended by Watts) or in some jurisdictions another location may be permitted.

Some jurisdictions do not permit the discharge drain destination to be hidden from view, on the theory that you won"t see a drip or leak and won"t thus detect an unsafe condition.

Other jurisdictions, such as in the U.K., permit the TPR valve drain line to be piped to a hidden location but require the installation of a tundish in the drain line at a suitable visible location.

The Tundish will allow the occupants to see that the TPR valve is leaking, and its air gap provides other plumbing sanitation and blockage protection features.

Outdoor terminations of a T&P valve drain line may be permitted in some jurisdictions, even required, to avoid water damage inside the building. However unless a tundish device is properly included such installations are unsafe. And piping a T&P drain line outside in freezing climates is unsafe because a dripping line may freeze and become blocked.

TPR Valve Mounting Leaks: Check for leaks around the valve where it is mounted on the boiler or boiler piping. This is a TPR valve defect, not a TPR discharge tube defect, but depending on the valve position and location, a leak around the TRP valve mount may send water (or corrosion or mineral salts) down the outside of the discharge tube, offering a valuable visual clue and possibly being mistaken for a defect in the tube itself

I am ... in the process of selling a condo I own. I got this request for repairs for the hot water heater with a picture of the heater. On the picture it shows the that the discharge line is above the TPR valve, and that this is a problem (see description on attachment). This doesn"t make any sense to me. Can you help me decide what the best action would be? thanks. - R.N. 7/11/2013

The photo is a bit difficult to read but if you look closely where the two flexible copper lines enter the wall behind the water heater, you"ll see that the smaller leftmost flexible tube, connected back to the water heater TP valve, enters the wall at a height above the valve outlet opening. What the home inspector said was perfectly correct and represents a safety hazard.

The temperature/pressure relief valve on a water heater is connected to a drain line so that if the valve opens someone nearby is not shot in the face with hot water. The discharge drain extension is typically taken to just a few inches above the floor or in some jurisdictions it may be directed outdoors - a solution that I think is risky because IF the valve should be leaking, dripping, etc., one wants to notice that and fix it to keep the system safe.

The inspector"s report makes a valid point: we should never route the discharge tube "up" from the actual outlet opening of the TP valve. That"s because if the valve should develop a small leak or be discharged on occasion, the up-routed discharge tube will keep water and debris remaining in the tube at the valve outlet where debris or mineral accumulation clog the valve or interfere with its operating spring.

The result over time could be that the valve becomes clogged and would then fail to open in a true emergency - risking, ultimately a dangerous BLEVE or water heater explosion.

Watch out: ALSO, I suspect from the photo that your water heater has a discharge tube that directs the valve outlet into a wall and going to who knows where. If the other end of that line is not already readily visible and in a location where it would be noticed, that too would be unsafe and improper.

The FIX for this unsafe condition is usually trivial: the discharge tube must be routed only "downwards" from the TP valve outlet opening, and the end of the discharge tube must be in a readily accessible, visible, and safe location. You"d probably find these same instructions in the installation manual for the water heater.

The COST for this repair should be no more than a simple plumbing service call and perhaps a few piping connections. What would make sense to me and what would be most economical would be to combine this repair with any other plumbing repairs that are needed at the home.

10. Terminate not more than 6 inches (152 mm) and not less than two times the discharge pipe diameter above the floor or waste receptor flood level rim.

14. Be one nominal size larger than the size of the relief-valve outlet, where the relief-valve discharge piping is constructed of PEX or PE-RT tubing. The outlet end of such tubing shall be fastened in place.

10. Terminate not more than 6 inches (152 mm) above and not less than two times the discharge pipe diameter above the floor or flood level rim of the waste receptor.

Some model and adopted building and plumbing codes expressly prohibit discharging the TPR valve out of the room containing the heating appliance that it is intended to protect.

1. All pressurized storage-type water heaters and unfired hot water storage tanks shall be equipped with one or more combination temperature and pressure relief valves. The temperature steam rating of a combination temperature and pressure relief valve or valves shall equal or exceed the energy input rating in BTU per hour of the water heater. No shut off valve or other restricting device may be installed between the water heater or storage tank and the combination temperature and pressure relief valve.

2. All pressurized non-storage type water heaters shall be provided with a pressure relief valve installed at the hot water outlet with no shut off valve between the heater and the relief valve.

3. Temperature and pressure relief valves shall be installed so that the sensing element of the valve extends into the heater tank and monitors the temperature in the top 6 inches of the heater or tank.

5 (e) The discharge pipe shall be installed to drain by gravity flow to a floor served by a floor drain or to a receptor in accordance with s. Comm 82.33 (8).

The outlet of the discharge pipe shall terminate within 6 inches over the floor or receptor, but not less than a distance equal to twice the diameter of the outlet pipe. The discharge pipe may not be threaded.

5 (f) The discharge pipe for a water heater shall terminate within the same room or enclosure within which the water heater or hot water storage tank is located.

WISCONSIN PLUMBING CODE, Chapter SPS 382, DESIGN, CONSTRUCTION, INSTALLATION, SUPERVISION, MAINTENANCE AND INSPECTION OF PLUMBING [PDF] (2016) retrieved 2019/11/13 original source: https://docs.legis.wisconsin.gov/code/admin_code/sps/safety_and_buildings_and_environment/380_387/382.pdf

Illustrated here in a photo and sketch you can see that the relief valve drain line can, where local codes approve, be routed "up" to carry discharge across a ceiling and then down to an approved drain discharge location provided that a special draining device, shown as a spiral-wound small-diameter copper tube is attached to drain the residue water in the vertical section of the drain line after a discharge.

Later explanation from Mr. Nesbitt clarified that the copper pigtail is a small diameter "drain" intended to remove water from the vertical portion of the relief valve up-piped drain line after the valve has discharged water during an over-pressure or over-temperature or test condition.

It"s not a control nor thermocouple, it"s simply a small diameter drain. The small diameter and flow resistance of the coiled tubing causes any significant volume of TPR valve discharge to be routed up through the vertical TPR valve drain line from the tee, and the combination of tee and short copper nipple connected to the wound copper tubing are probably intended to prevent standing water or debris accumulation at the mouth of the TPR valve itself.

The pigtail drain may appear to work perfectly to drain the residing water in the vertical section of the discharge line for the relief valve at initial installation and testing, experience suggests to us that debris, especially mineral scale, is epidemic at water heater relief valves, especially if the leak at the valve is a slow drip.

Some details including the design, the pigtail connection (presumably to a shutoff control) and research supporting this up-draining valve would be helpful.

It would be useful to know what research was done to support accepting this up-draining TPR design, presumably using a temperature sensor that shuts down the boiler if hot water is found at the bottom of that tee at the TPR valve outlet.

In our OPINION that is an unsafe and questionable relief valve design in that any TPR that drains "up" is at risk of ultimately depositing mineral salts that can lead to the valve refusing to open in response to an over-temperature or over-pressure condition in the boiler, risking a catastrophic BLEVE explosion.

worse, draining the valve "up" as shown, means that a slow drip or leak won"t be discovered by visual inspection until it has leaked so long as to fill that up-sloping TPR drain that, we hope, ultimately empties at a visible location.

In our OPINION the design you show violates CA §608.5 Discharge Piping 608.5 Discharge Piping - The discharge piping serving a temperature relief valve, pressure relief valve, or combination of both shall have no valves, obstructions, or means of isolation and be provided with the following:Equal to the size of the valve outlet and shall discharge full size to the flood level of the area receiving the discharge and pointing down.

CALIFORNIA §608.3 EXPANSION TANKS, AND COMBINATION TEMPERATURE AND PRESSURE-RELIEF VALVES - retrieved 2021/11/19 original source: up.codes/viewer/california/ca-plumbing-code-2016/chapter/6/water-supply-and-distribution#608.0

CALIFORNIA §608.4 PRESSURE RELIEF VALVES retrieved 2021/11/19 original source: up.codes/viewer/california/ca-plumbing-code-2016/chapter/6/water-supply-and-distribution#608.0

A water system provided with a check valve, backflow preventer, or other normally closed device that prevents dissipation of building pressure back into the water main, independent of the type of water heater used, shall be provided with an approved, listed, and adequately sized expansion tank or other approved device having a similar function to control thermal expansion.

Such expansion tank or other approved device shall be installed on the building side of the check valve, backflow preventer, or other device and shall be sized and installed in accordance with the manufacturer"s installation instructions.

A water system containing storage water heating equipment shall be provided with an approved, listed, adequately sized combination temperature and pressure-relief valve, except for listed nonstorage instantaneous heaters having an inside diameter of not more than 3 inches (80 mm).

Each such approved combination temperature and pressure-relief valve shall be installed on the water-heating device in an approved location based on its listing requirements and the manufacturer"s installation instructions. Each such combination temperature and pressure-relief valve shall be provided with a drain in accordance with Section 608.5.

Each pressure relief valve shall be an approved automatic type with drain, and each such relief valve shall be set at a pressure of not more than 150 psi (1034 kPa). No shutoff valve shall be installed between the relief valve and the system.

The discharge piping serving a temperature relief valve, pressure relief valve, or combination of both shall have no valves, obstructions, or means of isolation and be provided with the following:

A water-heating device connected to a separate storage tank and having valves between said heater and tank shall be provided with an approved water pressure relief valve.

Where a hot-water storage tank or an indirect water heater is located at an elevation above the fixture outlets in the hot-water system, a vacuum relief valve that is in accordance with CSA Z21.22 shall be installed on the storage tank or heater.

CALIFORNIA §761. SAFETY VALVES AND PRESSURE RELIEVING DEVICES, BOILERS [PDF] retrieved 2021/11/19 original source: https://www.dir.ca.gov/title8/761.html

(a) Each power boiler, nuclear boiler, and high temperature water boiler shall have safety valves or pressure relieving devices constructed, stamped and installed in accordance with the applicable section of the Code, except:

(2) Upon written request by the employer, the Division may permit three-way two-port valves to be installed under two safety valves, each with the required relieving capacity, provided they are so installed that both safety valves cannot be closed off from the boiler at the same time and provided the three-way valve will permit at least full flow to the safety valve in service at all time.

(b) The user shall maintain all pressure relieving devices in good operating condition. Where the valves cannot be tested in service, the user shall maintain and make available to the inspector records showing the test dates and set pressure for such valves.

(c) Pressure relieving devices with open discharge installations shall have piping and supports designed for pressure relief reaction forces in accordance with Appendix II of ANSI B 31.1.

I appreciate the significant convenience of being able to route a TPR valve discharge line up and thence horizontally and then "down" to a more-convenient discharge location, and now that we"ve got your added detail I understand the theory of a copper pigtail drain on the down-end of a Tee into which the water heater or boiler TPR valve is discharging.

It would be helpful to see the actual California plumbing code text on this detail and also useful to know what long-term testing and field experience have shown about the safety and reliability of this approach.

OPINION: If the small diameter pigtail drain clogs the homeowner will never know it. In normal water heater operation there should be no discharge from its TPR valve, so if later a slow drip at the valve leads to a clogged pigtail drain that condition may be indistinguishable from a perfectly functional installation.

You might detect a clogged pigtail drain on an upwards-piped relief valve drain during an annual test of the TPR valve: the valve is opened to discharge and then closed; afterwards you should see a small volume of water exiting from the pigtail drain as the remaining water in the up-piped larger diameter TPR discharge tube drains out through the pigtail.

Really? While TPR valves may come with an instruction to test the valve annually, in five decades of building inspections of thousands of buildings we have not found more than a handful of building owners who ever test a relief valve nor even know of that requirement.

In my opinion the fundamental error in ANY up-piping of ANY TPR valve is that the design is unsafe because of the possibility of accumulation of scale or other debris in that water reservoir leading to blocking of the valve"s operation when needed.

It"s a similar hazard to the one that occurs even in a down-piped TPR valve when the valve is constantly dripping or leaking. That passage of water leaves scale that ultimately blocks the valve.

Werner Sölken offers a nice explanation of these concerns. The company points out that ANY backpressure on a conventional pressure relief valve of the type commonly used on residential water heaters (disc and spring type design) will see a reduction of its opening response if there is any backpressure on the valve, such as from debris, or even from standing water in a discharge tube piped upwards (though I suspect the pressure difference in most buildings would be small).

Excerpt: A conventional safety Relief Valve is a pressure Relief Valve which has its spring housing vented to the discharge side of the Valve. The operational characteristics (opening pressure, closing pressure, and relieving capacity) are directly affected by changes of the back pressure on the Valve."

Allied Valve raises another objection that may pertain to your up-piped relief valve discharge piping: possible loading on the valve body itself if the piping does not support its own weight.

Allied Valve, 3 THINGS TO AVOID WHEN INSTALLING & OPERATING SAFETY VALVES [PDF] Allied Valve, 4119 State St., Riverdale IA, 52722 Tel: 800-827-1197 Web: alliedvalveinc.com - retrieved 2022/01/12 original source: https://alliedvalveinc.com/the-valve-expert/3-things-avoid-installing-operating-safety-valves/

Excerpt: "Stress from Improperly-supported discharge piping" Discharge piping must be installed so that it supports its own weight and does not put any weight or strain on the valve itself. According to the National Board of Boiler and Pressure Vessel Inspectors, improperly supported discharge piping is one of the top problems that can prevent valves from operating normally.

Discharge piping connected to the device must be supported so as not to impart any loadings on the body of the device. These loadings could affect or prevent the proper operation of the device including proper reclosure after operating

In sum, a relief valve discharge tube that is not pointing downwards may become unsafe. I agree that the worst does not always happen; if it did there would be no doubters. But the risk of a BLEVE explosion and the results of such a blast are so serious as to be considered carefully.

TPR valves drip far more often than they flow at volume. Slow drips easily leave scale that can clog a 1/8" diameter spiral tube with crimped end pretty quickly.

Then this and another pressure relief valve on a furnace boiler were overlooked for code violations in an official inspection--which I arranged--which took all of five minutes.

They don"t seem to care to look as closely at things like temperature and pressure relief valves as your inspection website does--but I wish.

The relief valve discharge tube is down-sized, smaller than the opening of the relief valve itself, reducing the valve"s ability to release heat, pressure, energy, should the heater over-heat

There is a drop of water at the discharge tube mouth that may be telling us that this valve leaks - which risks valve clogging by mineral scale and again risking that it cannot work safely if called-on to do so.

Incidentally, that water heater insulation is not required and in some installations can be itself unsafe, e.g. if it blocks view of or draining of a relief valve.

"Red tagging" is most-often done by a service technician. Others (building code inspector or home inspector) should write up the issue, and because it"s a life-safety concern, ought to notify all parties concerned, including owners and occupants of the building - in writing and orally.

The TPR valve needs to be installed in a tapping on the heater itself, near the top or on the top, as provided by the manufacturer; if you give the brand and model of water heater we may be able to find the installation manual that will show those exact details.

Watch out: a TPR valve not properly located risks failing to respond adequately to over-temperature or over-pressure in the water heater, risking a BLEVE explosion.

Watch out: Looking again at your photo it looks to me as if the TPR valve is connected to a pipe that goes "up" to some unknown destination or "down" to a valve that is closed; this is an unsafe and dangerous and incorrect installation.

Practically, you have to have enough space that when replacement of the TPR valve is needed there is working space to unscrew and remove the old one and get the new one in place - that might be just an inch or two past the test lever; and separately, you don"t want any dripping or discharge to wet the drywall lest you invite a mold contamination issue.

Practically - adding another messy detail, if your water heater sits in a drip or spill tray then the bottom of the discharge pipe will have to jog out and over and down to get past the outer edge of the drip tray, so the drip tray itself is going to space the heater and most of the discharge pipe a bit more-distant from the wall.

For example this gas fueled American Standard water heater - just an EXAMPLE - your heater may differ, lets the heater itself be as close as 2 inches from a wall, but that does NOT consider space to get the TPR valve on and off.

Take a look at where the TPR valve is connected to your water heater; if it"s on a side (near the top of course) then you need working space for the valve.

If the TPR valve is connected off of a tapping on the top of the water heater (as is on some models) then there"s probably plenty of working space there and the discharge tube could be quite close to the wall - but considering the practical warnings I gave above.

Above is an illustration of an [American Standard] electric water heater installed with a drain pan - notice the relief valve discharge pipe routing.

Even though the discharge of water into an area may not, in your opinion, cause damage to the building, the point of discharge must be visible so that someone can spot trouble (leaks) before a catastrophe occurs

Your local building code inspector might indeed approve routing the relief valve discharge to a hidden and harmless location provided a Tundish is installed so that leaks can be detected.

Would it be acceptable to allow the T&P valve to simply dump into the crushed rock in the crawl space? Could the same be done with the condensate line?

It is common to see plastic discharge tubes on some PT valves and that"s an accepted practice provided the tubing is properly rated for the temperatures involved.

As you can see from the example I give below, a typical residential boiler relief valve costs less than $100. U.S. and a typical discharge tube of 3 or 4 feet or less costs less than $10. U.S.

Even if a plumber charged a minimum of an hour"s labor to unscrew the old valve and screw in the new one and its discharge tube that ought not amount to a substantial total (where I read "substantial" as hundreds of dollars) unless there was something rather unusual and costly going on in your home.

Recently we replaced our 14 year old Ultra 310 Boiler with a new Evergreen 399 Boiler. Our Ultra 310 boiler was professionally installed with a plastic PT valve a white plastic discharge tube. During a routine maintenance,

We now have a new Evergreen Boiler and the copper was removed and replaced with a blue plastic discharge tube. So, which should it be? We are puzzled.

There is water FLOWING from the DISCHARGE TUBE on my Triangle Tube, indirect fired water heater. (I shut of the water supply off to the tank so it isn"t spilling onto the floor.) Does this suggest that I need to replace the T&P relief valve?

Hi there just wondering why my TPR doesn"t discharge at all and i tested it by lifting the lever and it was flowing freely outside and stopped when i released it back?Is that normal?Thanks

I have a relief valve right on top of my steam boiler, it doesn"t have a discharge outlet but it has openings right on top of it where i see some, if not too much steam coming out, it should be replaced or it is normal?

Possibly. But it"s easy to check. Compare the actual boiler pressure when leaks are seen with the valve rating. Normally a hydronic heating boiler doesn"t run over 30 psi

Fillip, the valve should not be leaking, but before replacing it you need to know why it"s leaky, as the problem may not be the valve. Call your service company as this is va safety concern

Thanks for the information. Is there any requirement that the fitting and pipe extension is required to be made from copper? I came across a boiler where the fitting off the T&P and the extension to the floor is made of PVC. - Kevin 7/26/2011

Kevin the relief valve would itself tap into a metal fitting on the boiler or on older installations on metal heating piping. But the discharge tube on many new installations is plastic; it"s a pipe that rarely sees service and whose job is to divert hot water to the floor rather than onto a bystander. In that application most code officials accept PVC.

My new tankless water heater is in a place in my basement (finished) where there is no floor drain. A sump pit and pump exist in the area. Obviously if my relief valve activates, if it were to just be allowed to dump onto the floor, the water would travel through a finished part of my basement before reaching the drain.

Right now I have a piece of plastic tubing attached to the bottom of the 3/4" relief valve pipe. This is probably not the best or legal solution but it would keep my basement from flooding (so long as sump pump operates.) Is there a legal option of looping the relief valve discharge tube up through the band board of my house so it can drain to the outside?

Do not pipe the TP valve discharge tube UP - the result (because dripping or leaks can remain in the piping and valve opening) can be a clogged, failed TP valve and a fatal BLEVE explosion.

In a photo above on this page you can see a flexible 3/4" copper tube used in the routing of the discharge of a TP valve from the top of a water heater. No one called out the use of that piping material itself as a hazard, but there can be hazards nonetheless depending on how that tube is routed - such as to a hidden location without a Tundish or routed "up" from the TP valve itself.

So ... it depends. If for example someone installed a flexible line to replace a straight downtube running down the side of a water heater from the TP valve, I"d be worried that some fool would come along and bend the tubing "up" - as nothing prevents them from doing so. Maybe to get it out of the way of a basketball or something. The result is a dangerous blockage of the TP valve and the risk of a BLEVE explosion. SO if I I were a building inspector given final authority I"d object to that installation. But I might not object to use of the same tubing connecting properly between a valve"s discharge opening and a proper destination.

Discharge line must always be installed to avoid water damage and scalding injury, when valve operates. Discharge line must be same size as valve outlet, be pitched down for free draining, and have no shut-off valve or obstructions throughout its entire length. Discharge line termination point should be visible to observe any discharge.

2. it is not permissible to terminate a TPR valve discharge line with a threaded fitting - the reasoning is that it"s too easy for someone to screw a cap onto a dripping line, leading ultimately to a BLEVE explosion.

RELIEF VALVE DISCHARGE TUBE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

phone (610) 252-7355, original source http://www.harvel.com/piping-systems/gf-harvel-cpvc-industrial-pipe, copy on file as GF_CPVC Industrial Pipe _ CPVC Pipe.pdf.

(Model BR4EC - Water Pressure Reducing Valve With Thermal Expansion Relief Valve … Discontinued Products,Pressure Reducing Valves,Wilkins Water Control,,R4EC,4EC)

[6] A.O. Smith"s Form No. 4778* All about Deliming Coil-Type/Tube-Type Commercial Water Heaters and Hydronic Boilers *Normally supplied when ordering Part No. 4930 Motorized Deliming Pump Kit

[7] "Building Owner Water Heater Safety Notice", Building Department, City of Colleyville TX, web search 09/24/2010, original source: http://www.colleyville.com/dmdocuments/Building%20

Water heater safety is imperative to the occupants of a building or structure. If improperly installed, water heaters can be detrimental to the structure, as well as being potentially fatal to its occupants. The proper installation of a water heater is so important that according to Texas State Law all water heater installations must be inspected by a state licensed plumbing inspector.

[9] Watts, 815 Chestnut Street, North Andover, MA, USA 01845-6098, web search 09/18/2010 original source: http://www.watts.com/pages/learnAbout/reducingValves.asp?catId=64

In small scale testing, the Mythbusters started with a small six gallon water heater and disabled all of its safety features under the theory of poor installation or neglect. While the water heater eventually ruptured, it did not explode like a rocket. The Mythbusters then upgraded to larger thirty gallon water heater which exploded with significantly greater force, sending the water heater several hundred feet into the air. In order to confirm the stated myth, the Mythbusters obtained a full size fifty two gallon water heater and built a shack around it with a roof that followed standard California building codes. The water heater eventually exploded, shooting through the roof five hundred feet into the air and disintegrating the shack. In light of these results, and the fact that there is documented evidence corroborating the myth, the Mythbusters deemed it confirmed.

Because of built in safety devices most water heaters safely operate day in, day out without any major problems. But don"t let the excellent safety record of water heaters lull you into forgetting about the explosive potential of these marvels of convenience. When a water heater explodes, it releases a tremendous blast force which can easily demolish a building.

Randall Hilton and crew, with help from the Service Roundtable has prepared this video of a water heater explosion as a demonstration of the explosive power of a simple water heater. The hot water tank explodes using the steam pressure that any water heater can generate when the thermostat and temperature pressure relief valve (T&P valve or PT valve) malfunction. We were impressed by how far the tank flew after the water heater exploded. Click on the links below to view the video. Then, visit the Q&A page for warning signs as well as simple steps which can help you prevent your own water heater from exploding.

TECHNICAL REFERENCE GUIDE to manufacturer"s model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop Weldon & Associates

boiler safety valve discharge piping price

There is a wide range of safety valves available to meet the many different applications and performance criteria demanded by different industries. Furthermore, national standards define many varying types of safety valve.

The ASME standard I and ASME standard VIII for boiler and pressure vessel applications and the ASME/ANSI PTC 25.3 standard for safety valves and relief valves provide the following definition. These standards set performance characteristics as well as defining the different types of safety valves that are used:

ASME I valve - A safety relief valve conforming to the requirements of Section I of the ASME pressure vessel code for boiler applications which will open within 3% overpressure and close within 4%. It will usually feature two blowdown rings, and is identified by a National Board ‘V’ stamp.

ASME VIII valve- A safety relief valve conforming to the requirements of Section VIII of the ASME pressure vessel code for pressure vessel applications which will open within 10% overpressure and close within 7%. Identified by a National Board ‘UV’ stamp.

Full bore safety valve - A safety valve having no protrusions in the bore, and wherein the valve lifts to an extent sufficient for the minimum area at any section, at or below the seat, to become the controlling orifice.

Conventional safety relief valve -The spring housing is vented to the discharge side, hence operational characteristics are directly affected by changes in the backpressure to the valve.

Balanced safety relief valve -A balanced valve incorporates a means of minimising the effect of backpressure on the operational characteristics of the valve.

Pilot operated pressure relief valve -The major relieving device is combined with, and is controlled by, a self-actuated auxiliary pressure relief device.

Power-actuated safety relief valve - A pressure relief valve in which the major pressure relieving device is combined with, and controlled by, a device requiring an external source of energy.

Standard safety valve - A valve which, following opening, reaches the degree of lift necessary for the mass flowrate to be discharged within a pressure rise of not more than 10%. (The valve is characterised by a pop type action and is sometimes known as high lift).

Full lift (Vollhub) safety valve -A safety valve which, after commencement of lift, opens rapidly within a 5% pressure rise up to the full lift as limited by the design. The amount of lift up to the rapid opening (proportional range) shall not be more than 20%.

Direct loaded safety valve -A safety valve in which the opening force underneath the valve disc is opposed by a closing force such as a spring or a weight.

Proportional safety valve - A safety valve which opens more or less steadily in relation to the increase in pressure. Sudden opening within a 10% lift range will not occur without pressure increase. Following opening within a pressure of not more than 10%, these safety valves achieve the lift necessary for the mass flow to be discharged.

Diaphragm safety valve -A direct loaded safety valve wherein linear moving and rotating elements and springs are protected against the effects of the fluid by a diaphragm

Bellows safety valve - A direct loaded safety valve wherein sliding and (partially or fully) rotating elements and springs are protected against the effects of the fluids by a bellows. The bellows may be of such a design that it compensates for influences of backpressure.

Controlled safety valve - Consists of a main valve and a control device. It also includes direct acting safety valves with supplementary loading in which, until the set pressure is reached, an additional force increases the closing force.

Safety valve - A safety valve which automatically, without the assistance of any energy other than that of the fluid concerned, discharges a quantity of the fluid so as to prevent a predetermined safe pressure being exceeded, and which is designed to re-close and prevent further flow of fluid after normal pressure conditions of service have been restored. Note; the valve can be characterised either by pop action (rapid opening) or by opening in proportion (not necessarily linear) to the increase in pressure over the set pressure.

Direct loaded safety valve -A safety valve in which the loading due to the fluid pressure underneath the valve disc is opposed only by a direct mechanical loading device such as a weight, lever and weight, or a spring.

Assisted safety valve -A safety valve which by means of a powered assistance mechanism, may additionally be lifted at a pressure lower than the set pressure and will, even in the event of a failure of the assistance mechanism, comply with all the requirements for safety valves given in the standard.

Supplementary loaded safety valve - A safety valve that has, until the pressure at the inlet to the safety valve reaches the set pressure, an additional force, which increases the sealing force.

Note; this additional force (supplementary load), which may be provided by means of an extraneous power source, is reliably released when the pressure at the inlet of the safety valve reaches the set pressure. The amount of supplementary loading is so arranged that if such supplementary loading is not released, the safety valve will attain its certified discharge capacity at a pressure not greater than 1.1 times the maximum allowable pressure of the equipment to be protected.

Pilot operated safety valve -A safety valve, the operation of which is initiated and controlled by the fluid discharged from a pilot valve, which is itself, a direct loaded safety valve subject to the requirement of the standard.

The common characteristic shared between the definitions of conventional safety valves in the different standards, is that their operational characteristics are affected by any backpressure in the discharge system. It is important to note that the total backpressure is generated from two components; superimposed backpressure and the built-up backpressure:

Subsequently, in a conventional safety valve, only the superimposed backpressure will affect the opening characteristic and set value, but the combined backpressure will alter the blowdown characteristic and re-seat value.

The ASME/ANSI standard makes the further classification that conventional valves have a spring housing that is vented to the discharge side of the valve. If the spring housing is vented to the atmosphere, any superimposed backpressure will still affect the operational characteristics. Thiscan be seen from Figure 9.2.1, which shows schematic diagrams of valves whose spring housings are vented to the discharge side of the valve and to the atmosphere.

By considering the forces acting on the disc (with area AD), it can be seen that the required opening force (equivalent to the product of inlet pressure (PV) and the nozzle area (AN)) is the sum of the spring force (FS) and the force due to the backpressure (PB) acting on the top and bottom of the disc. In the case of a spring housing vented to the discharge side of the valve (an ASME conventional safety relief valve, see Figure 9.2.1 (a)), the required opening force is:

In both cases, if a significant superimposed backpressure exists, its effects on the set pressure need to be considered when designing a safety valve system.

Once the valve starts to open, the effects of built-up backpressure also have to be taken into account. For a conventional safety valve with the spring housing vented to the discharge side of the valve, see Figure 9.2.1 (a), the effect of built-up backpressure can be determined by considering Equation 9.2.1 and by noting that once the valve starts to open, the inlet pressure is the sum of the set pressure, PS, and the overpressure, PO.

In both cases, if a significant superimposed backpressure exists, its effects on the set pressure need to be considered when designing a safety valve system.

Balanced safety valves are those that incorporate a means of eliminating the effects of backpressure. There are two basic designs that can be used to achieve this:

Although there are

boiler safety valve discharge piping price

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