Another Leaky PRV


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Old 02-12-17, 01:03 PM
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Another Leaky PRV

Plumber replaced leaky pipe on boiler. PRV started leaking (from outlet pipe). Boiler repair company replaced PRV - which then leaked from valve stem. $1351 later I still have a leak.
Configuration - 2 PRV share same outlet. Outlet goes up as boiler is in basement without a drain. Company replaced PRV with same model - result was same - leaks from stem. Company threw out old valve so I don't know what model it was. I know that I need to figure out why PRV is leaking but right now I want to put a valve in that does not leak from stem. Have read about bellows, bonnets, etc. I have no idea what type of valve to buy if there is going to be back pressure (pipe runs uphill to get water out of basement). Also, any suggestion as to what model to us will be appreciated.
John -
 
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Old 02-12-17, 01:22 PM
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What do you mean by PRV? Common usage has those initials meaning Pressure Reducing Valve or Pressure Relieving Valve. It is best that you use the term Safety Valve if you are referring to the device that protects the boiler from excess pressure.

You also need to tell us much more about the system. Including pictures always helps. Pictures need to be well lit and in focus or they are useless. Pictures from far enough away to see how the various parts are connected are preferred. If close-ups are needed we will ask for them.
 
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Old 02-12-17, 02:08 PM
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OK - fair enough on use of acronyms. It is the Pressure Relief Valve. It is a Buderus G124 boiler. I am not trying to understand why the Relief Valve is leaking - I will tackle that later. The valve that the boiler repair company used is a Watts M330. The installation instructions for this valve state that the discharge pipe has to run downhill. Mine does not and cannot.
I am guessing that the original valve may have gotten some contaminates in the seat when the piping was replaced. The plumber had to bleed air out of the system and he used the manual release on the old relief valve to do some of this. For whatever reason when he left the original valve started leaking, but the water was discharged outside of my house, through the discharge pipe that runs from the basement, up to the first floor, and then outside. I contacted a boiler repair company at that point. They have installed 2 brand new WATTS M330 valves with the same outcome. The water now comes out from the top of the valve. Not surprising as the instructions say the discharge pipe has to run down hill. To test the theory that this is the wrong valve I hooked a hose to the discharge pipe. When I turned the hose on, which put back pressure on the valve, sure enough water comes shooting out of the top of the Pressure Relief Valve. The valve is not made to be installed in a configuration where there will be back pressure. What I am trying to find is someone who can tell me what configuration of a pressure relief valve I need if the discharge pipe runs up hill. And, I can open a spigot that is in my discharge pipe so that it will drain in the basement. If I do this, sure enough the water does not come out of the stem at the top of the relief valve.
 
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Old 02-12-17, 02:26 PM
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There shouldn't be pressure on the stem unless the relief valve lifts. I think what is going on is because your relief discharge piping runs upward - not an ideal situation. When you or your plumber manually lifts the relief valve, the discharge pipe fills with water and it leaks back past the stem. Your running the discharge pipe outside isn't good either - what if it freezes? Personally, I don't think it is acceptable have a boiler installed where there is no floor drain.

There may be Rube Goldberg ways to alleviate the problem, but I won't go there.
 
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Old 02-12-17, 02:45 PM
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You can NOT run the relief valve on a upward slop per code. Especially from the basement to the 1st floor..

If the installer that replaced the relief valve did not fix that when he was there then he is and untrained and did you an injustice. as the relief valve can and will plug with rust. If you never saw a boiler blow up in a home, then here it is..

You have a time bomb on your hands.

Powerful Boiler Explosion Blows Through Home but Washington Family Survives Video - ABC News

The relief valve was originally leaking because of your exp tank or fill valve most likely..
 
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Old 02-12-17, 02:46 PM
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Old 02-12-17, 02:58 PM
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Thanks for the many insights. I realize it is not currently up to code but it evidently was 15 years ago. It is also not code to have 2 relief valves using the same discharge pipe - but it evidently was 15 years ago. And the valve that was originally installed did not leak with the back pressure. I know this for a fact because I had to replace the TPV on the attached water heater - which shares the same discharge pipe as the boiler. When that valve started leaking, all the water went up the pipe and outside.
So I "simply" have to find a release valve that will work in this configuration, which I will do.
 
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Old 02-12-17, 03:01 PM
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Cut that relief valve line out and pipe it to within 6" to the floor period!!!

[ATTACH=CONFIG]77144[/ATTACH]
 
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Old 02-12-17, 03:06 PM
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I realize it is not currently up to code but it evidently was 15 years ago. It is also not code to have 2 relief valves using the same discharge pipe - but it evidently was 15 years ago.
Was never code as long as I been a plumber 30+ years

So I "simply" have to find a release valve that will work in this configuration, which I will do
Very bad way of thinking..

If any advice here is other then to bring up the non conforming relief valve piping you have to code. I will close this thread..

You , your family, and everyone in your home is in danger. Why would you put anyone in harms way?
 

Last edited by lawrosa; 02-12-17 at 03:14 PM. Reason: spelling
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Old 02-12-17, 03:23 PM
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Not surprising as the instructions say the discharge pipe has to run down hill.
Codes always require that equipment be installed in accordance with the manufacturer's instructions. If you install a new relief valve, you have to comply with the current instructions.
 
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Old 02-12-17, 04:20 PM
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I wish to god that people would stop referring to a SAFETY valve as a relief valve. They are NOT the same!

I worked in the power generation field for more than thirty years, retired for more than a decade now so I have more experience than Mike. I've worked in plants that were built in the early 1900s and I have NEVER seen a safety valve that had a vertical discharge that didn't also have a minimum of a 1/2 inch nominal pipe size drain. I have, on rare occasion, seen two safety valves piped to a single discharge pipe but ONLY when the pipe was properly sized to eliminate any "back pressure" on the safety valve.

Your installation is flat-out wrong and always has been. Why do you even have two safety valves?

Pictures may help us to help you better.
 
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Old 02-13-17, 02:21 PM
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Well, in the end I received what I paid for.

From the Washington State Code --
608.5 Drains. Relief valves located inside a building shall be provided with a drain, not smaller than the relief valve outlet, of galvanized steel, hard drawn copper piping and fittings, CPVC, PP, or listed relief valve drain tube with fittings which will not reduce the internal bore of the pipe or tubing (straight lengths as opposed to coils) and shall extend from the valve to the outside of the building, with the end of the pipe not more than two (2) feet (610 mm) nor less than six (6) inches (152 mm) above the ground or the flood level of the area receiving the discharge and pointing downward. Such drains may terminate at other approved locations. No part of such drain pipe shall be trapped or subject to freezing. The terminal end of the drain pipe shall not be threaded.
EXCEPTION:
Where no drainage was provided, replacement water heating equipment shall only be required to provide a drain pointing downward from the relief valve to extend between two (2) feet (610 mm) and six (6) inches (152 mm) from the floor. No additional floor drain need be provided

SO
I have a boiler that the relief valve - That is what the manufacturer calls it

M335M1, 3/4" Male Pressure Relief Valve

has a drain pipe that goes vertically up from the basement to the heated floor of the first floor where it is protected from freezing (unless the boiler is not working and my house is below freezing). It exits the house straight downward so that there can be no water in the exposed section. As to getting sediment in the drain, the engineers that designed it specified a spigot at the lowest point that is used to totally drain the pipe, and flush it, on an annual basis.

I have 2 relief valves because the hot water exchange unit - that is attached to the boiler, also has a temperature/pressure relief valve.

SO, thanks for your time but, like the boiler repair company, it appears that I have to keep searching for the model of pressure relief valve that was originally installed on the system.


>wine
 
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Old 02-14-17, 04:06 PM
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Furd,
Just for informational purposes. I know you worked in Industrial plants and I have about 20 yrs. in Industrial myself along with many more in residential so I understand what your saying but in all fairness to the people on this sight using the pressure relief valve terminology that is what they are called in my area also.

If it's a relief valve for hot water it's a PRV. If it's for steam which it sounds like you are used to it is called a safety valve or we used to call them steam popoff valves also.

Even at the suppliers I deal with, this is the terminology they use when ordering stock.
Steam = safety, Hot water = PRV, Domestic water = T&P valve (temp & pressure).

Just my thoughts Furd. I know it's been driving you nuts.
 
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Old 02-15-17, 11:14 AM
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I'm caught in a bit of a time warp, having served in the U.S. Navy in the 1960s. Their terminology then was that "safety valves" were used on drum-type steam boilers, and "relief valves" were used on other applications, such as water and oil lines. The design of steam boiler safety valves is complicated, I think, by the need to provide a specified percent blowdown between opening (lifting) and reseating - to avoid rapid opening and closing during discharge due to flashing of water into steam during a discharge.

But, in modern parlance, there seems to be some overlap in the terminology.
 
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Old 03-14-17, 12:31 PM
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Fixed

Well, I finally resolved this.
If anyone is reading this in a desperate attempt to fix their leaking pressure relief valve -- there is valuable information elsewhere -
Recap of what others have written
1) Make sure your expansion tank is not full of water - it looks like a small propane tank and is tied into your hot water supply. It's main purpose is to relieve the increased pressure as the water heats up. It has a bladder (like a balloon) in it. If you tap on it with a screwdriver you should be able to discern a difference in tone between the side that is attached to the hot water and the other side. Mine was OK, but I did set the air pressure. My system is designed to have 12 pounds of pressure when the system is cold. I shut off the heat, let things cool down and used the pressure release valve to let all the pressure out of the system. Mine has a tire stem on the end with the bladder. You can add air with a bicycle pump or let pressure out by pushing on the metal valve in the stem.

As to my particular configuration, my system is designed to have static back pressure in the outlet pipe for the pressure relief valve. You could have this for a couple of reasons - you might have more than one pressure relief valve sharing the same discharge pipe or your discharge pipe may run uphill. I had both. They make pressure relief valves that will work in this configuration. I used a Watts 174A, Model M3. There are others that will work but the valve has to have a membrane between the discharge pipe and the spring assembly. The replacement that was used on mine did not have this and whenever the relief valve operated (to relieve excess pressure) the water would come out of the spring assembly and run all over my basement.
Finally - the underlying problem was the input water pressure regulator. I suspected it (through a process of elimination and education). To test it I placed a pressure meter on the hot water side (I had a standard water spigot on mine). I then shut off the boiler and the incoming water supply, once again used the relief valve to drain off all the pressure. When I turned the water supply back on the pressure went to about 20 PSI (it took 3 or 4 hours to get there). It should not have gone above 12PSI.
So, I replaced the incoming water pressure regulator and - no more leaks.

Off to my next project.
 
 

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