Importance of Relief Valve Piping!

Mike Bash

I had posted this on the community board but wanted more people to see it so I am putting it here also.

I wanted to take a few minutes to tell a story about the importance of piping the discharge from relief valves to the floor.

Several years ago I went on a call for a second opinion on a job. I am not a boiler expert but went to see what I could do. They had a leak in the copper return line and someone said they would fix it. They cut the leaking fitting out and never came back. Everything sat drained all summer and of course it was now turning cold and they wanted heat.

I could not tell what it would take until I got started so they gave me approval to see what I could do. First I replaced the missing fittings and pipe. Next I started to refill the system. Immediately the relief valve started leaking. It must have been open and just stuck that way. Next I replaced that and started filling again. This time everything held.

Now to get the air out. As I stated before I am not an expert, Plumbing is what I do. So I did what I normally do. I did not have a way of purging the air other then just starting to bleed the radiators. Now how I usually do this if I am by myself is close the expansion tank valve, and crack the quick fill until it hits around 25psi. Then I start to bleed the air out. When it slows I go back and fill it up again. I think my first mistake was I cranked up the thermostat so I could keep track of how far I was getting heat. I just kept filling and bleeding and feeling the pipes to see if I was getting the heat anywhere.

It seamed I was getting close to having it start to work, I was getting heat most of the way around the basement. No remember the boiler is firing and the circulator is trying to pump all this time. I had built up the pressure again, walked around and felt the pipes, and before I went back up stairs to the next radiator I went back over to check the pressure one more time. I could not remember if I had filled it again this trip or not. I got about 7 feet away and I heard a loud noise. The relief valve blew wide open. It didn't start with a drip or any warning, just went wide open. The water and steam hit me square in the chest.

I had mostly second degree burns with some third degree from my belt to my chin. My heavy pants must have helped but my thin shirt did not stop anything. I am just thankful I didn't get it in the face. A few more steps and I would have been looking straight at it. Several days in the burn unit and many weeks off work will teach you an important lesson.

I do not blame anyone, after all I was the one who put the new valve on. The old one was not piped to the floor either or I would have used the old pipe. I should have not been so lazy and done it right. Anyway when ever you are around any appliance that has a relief valve and it's not installed correctly please point it out and have it corrected. A few feet of pipe can save a lot of pain and suffering.

Thank you for your time.

Steve_35

A great point

and it doesn't hurt to remind us. Relief tubes on boilers and water heaters are definitely a must and something we look ofr on every job we're on.

Ron Schroeder_4

Hi Mike,

Thanks for the safety reminder. We all need it now and then. I hope you have recovered.

This also reminded my of a problem that I see often: Where do you run the relief pipe in a basement where there is no floor drain at all?

Thanks and be safe,

Ron

jim sokolovic

Hope this post gets...

well read - and possibly protects others from the same nasty misfortune. Think how easy it would be for some curious child to lift that lever, too. Thanks, Mike!

Caselli

Point it toward a drain ?

A friend bought a house recently, and the home inspector commented that the relief line from the water heater should be changed.

It came down to the floor and then elbowed to point at the floor drain.

He wanted it to terminate 6 inches above the floor, pointing straight down.

Any reason ? I told her maybe mice, etc., could more easily clog it up.. Best I could come up with.

Dale

Steam too

It was only in 1996 that the fuel gas code required steam boilers to be relief piped to the floor. I look at the old reliefs, still original from the 1930's and try to keep my face away when the boiler is running. Many have not outlet piping connection even if one wanted to add it.

oil-2-4-6-gas

.

i find myself more often than not walking into a boiler room and see nice reliefs with no drop leg --mind you some are 3/4-up to 4" valves most of them i have been able to put the relief -drop-leg in after explaining the danger and liability involved --yes they should terminate 6 foot from the floor-minimal 90's the idea is to get the full rating of the valves' relieving capacity --unless you are high pressure which must terminate up on the roof but of course local codes can be different--

Einsiedler_2

air gap

the 6" from floor line is to create air gap between pipe & drain in case drain failed & room flooded.

cheers!
EIN

Greg Swob

No one got hurt here,

this reminded me of my first trip into a mechanical room of a local professional building. Several water heaters were installed with the top-mounted T&P valves all facing the doorway as you walked into the room. Looked like you were facing a firing squad! Got it corrected before it ever became a problem. Greg

Caselli

back-siphonage

Thanks. I can buy that.

I thought of that too in the "etc.," but related to clogging of the relief line from flooding. But the real reason is some measure of protection against back-siphonage.

6" seems reasonable, but of course doesn't protect it from EVER being submerged. Probably assumes at that point the equipment would be have to be taken from service for safety or building cleanup.

Tony Conner_2

If It's...

...aimed somewhere, like with that 90*, somebody could get burned if they were in the path of discharge. If it's aimed vertically down, terminating 6" from the floor, I suppose you could still get your hand or foot under it, but you couldn't, y'know, be LOOKING up it, in case it lifts. If the discharge is too close to an obstruction, it'll block it. I have actually seen relief valves with the discharge lines terminating right up against a floor or wall. The flow would have been pretty much totally restricted. The relief valve capacity would have been almost zero. There might as well have been a closed valve in the line.