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TPR valve and TR valve


Ponyboy
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Just looked at a one year old water heater in a six story condominium building built in 1989. The inspected unit is on the second floor. A TPR valve is installed on the water heater but is plugged. A PR valve is installed on the hot water pipe above the water heater. Can the PR valve on the water pipe substitute for the TPR valve on the water heater? I called it out as a safety hazard and am concerned that all of the water heaters are installed in the same manner in this building.

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Can the PR valve on the water pipe substitute for the TPR valve on the water heater?

Simple answer...NO! Even if that "PR valve" was a TPR valve it is still supposed to have the sensor immersed in the top 6" of the water tank, not at a remote location. If it's just a pressure relief then you have no protection at all for excessive temperature. You did right calling it as a safety hazard. I can't see anyone (but an idiot) arguing with that.

BTW...no harm leaving that "extra" valve in place but the TPR at the tank needs to be unplugged and plumbed in an appropriate manner.

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BTW...no harm leaving that "extra" valve in place but the TPR at the tank needs to be unplugged and plumbed in an appropriate manner.

Why did the code require the TR valve in the plumbing system in the 1970 and 1980's anyway? My 1975 split level has both valves?

I don't think it did. If you look at the valve mounted high in the system, you'll probably discover that it's a TPR valve and that it's blow-off pressure is 125 pounds, not the 150 that is installed on the water heater.

It seems to be the way local plumbers figured out how to prevent the system from spewing water into basements around here. First, they install a 150 pound TPR valve on the tank and then end the pipe near the floor. Then they install a second valve - that blows off at 125 pounds - high up on the line with the discharge line to the outside.

I've seen it hundreds of times and it's always in a place where there's no way to plumb the discharge line from the tank TPR outside without incorrectly configuring the pipe so it slopes back toward the tank. Obviously, the idea is that the one high up on the line will release long before pressure in the system reaches the set point for the valve on the tank.

Get a flashlight and look closely at the tag on the upper valve on your setup.

ONE TEAM - ONE FIGHT!!!

Mike

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Mike, you are absolutely correct. After thinking about it, the 125 PSI valve should provide adequate pressure protection. I main TPR valve still needs to be opened. Also, the buyer is going to present my findings to the association, but we figure all the tanks in the building have been replaced in the same manner.

Below is a different installation which I just looked at, very common, but the valve is not immersed in the top 6" of the water tank. Is it wrong?

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Look closely at the RE sign on the tank. This is a great candidate for Jay Leno's headlines.

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. . . Below is a different installation which I just looked at, very common, but the valve is not immersed in the top 6" of the water tank. Is it wrong?. . .

Before you call it wrong, look carefully at the model number of the TPR valve. There are some with an extra long sensing element. These are designed to be used precisely as the one in your picture. The element in these is long enough to extend into the tank.

- Jim Katen, Oregon

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I did not call it as wrong, it had the XL marking, just checking with you guys. The tank is at the end of it's life anyway and needs replacement.

Why do you say that?

- Jim Katen, Oregon

Apparently it's an older tank. In picture #2 there's a sign that says new hot water tank, but under it on the service sticker, there's a hand written note saying it was installed in 1998.

I wouldn't replace it unless it was leaking.

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