Gas Hot Water Heater Tank and Pressure Relief Valve

[skadoo323]

Hello Everyone,

I have a gas water heater tank in my house, which does in fact have a Pressure Relief Valve from the side like most hot water heater tanks. Recently I have been noticing some water in the drip pan below the water heater. The water collects in the pan only when the water tank heater is on and heating the water. Above the hot water heater tank are two pipes, one for cold water which I think goes into the hot water heater tank and then another pipe which carries the hot water from the hot water heater tank (not sure if it matters, but these pipes are copper). On the cold water pipe which goes to the water heater tank, I noticed that there is a pressure vale of some sort. Unlike the main water line's pressure regulating valve, this one is not adjustable. Also this valve, which is somewhat in the shape of a "T" has an output line which is I think 1/2" PVC. I looked at my parent's place and my sister's place, but neither of their water tanks have a pressure regulating valve such as this which is connected to the cold water pipeline going into the hot water heater tank.

The water collected in the pan comes from this PVC piping, which is from the pressure regulating valve that is connected to the pipe providing cold water to the hot water heater tank. I noticed when the water is dripping from this PVC pipe, the copper cold water line pipe going to the hot water heater feels warm.

Any ideas on why the dripping occurs? Is this valve on the cold water line going to the hot water heater even needed? Just asking because a maintenance employee at one of my employer's offices said it is not needed and I could just plug it. I wanted to get some additional input before doing anything. Thanks!

[jnaas2]

The valve you are talking about is more then likely a pressure valve. When water heats up it expands and if there ie a backflow preventer in the water meter it will cause the water pressure in the house to increase until it blows a line or causes the pop off valve on the water heater to release the excess pressure. So plumbers install a small expansion tank on the cold water side near the water heater or a pressure limiting device like you are talking about. If you cap it put a pressure gauge on you water line and see what the pressure climbs up to, I think you will be surprised. You are right in asking questions, NEVER CAP A LINE NEAR YOU WATER UNLESS YOU KNOW WHAT IT DOES. This can cause the heater to explode if the wrong line is capped and can kill

[skadoo323]

I appreciate the fast reply. So I should leave it as it is? I think another issue is that my roommates have been back home for a bit and the hot water isnt being used much. Would that have any impact? Thanks again!

[HayZee518]

jnaas - isn't that fitting on the cold water line a siphon breaker? I had one of those on my hot water heater when I lived in Massachusetts

[skadoo323]

Also the city utility mentioned that the water coming to the house is at the proper pressure. Should I consider decreasing the water pressure from the main water pressure regulating valve that controls the water in the house?

[jnaas2]

I wouldnt have the city decrease the water pressure , but you may try turning the water supply off and opening all the valves in your house incase there are water hammer arrestors installed in the walls that have lost there air charge and they will allow the water heater to heat the water and keethe water pressure from rising to high As hayzee says that could be a siphon breaker but I have never seen one installed on a hot water heater before and you learn something new everyday

[hidden 1]

line pressure valve

I am about to install something just like you speak of into the cold line to hot water heater,,a pressure relief valve...the owners manual says it can be placed in line or a expansion tank for thermal expansion..im using the valve in line -off a tee with pvcpipe for exit but im using a 125psi as to pop before the 155 on heater,.its just a 2nd measure after installing a pressure reducing valve set at 50 -60(much bigger and better)..
-hope it helps

[Redwood]

Below is a posting I have made regarding high pressures on a potable water system. It was geared toward someone that had an initial burst of high pressure when opening a faucet. The concepts presented in the post apply to your situation as well and hopefully gives you the concepts needed to diagnose your problem. Post back once you have read it and applied the knowledge to your individual situation if you have any additional questions.

An actual measurement of the water pressure would be of great value to us. I would suggest a gauge with a lazy hand that records the highest pressure reached over a 24 hour period. Testing products - PlumbingSupply.com



Pressure above 80 PSI. indicate a Pressure Reducing Valve (PRV) should be installed. Do you have an existing pressure reducing valve? http://www.plumbingsupply.com/waterp...egulators.html



Of special interest to us is how and when the highest pressures occur.

1.) Lets say you have a pressure of 60 PSI. with the water flowing slightly. You shut off the flow and the pressure slowly creeps up to 120 PSI. and holds there. This would in most cases indicate a PRV is installed on the line and is set at 60 PSI. but it has failed and the pressure slowly leaks by until it reaches the 120 PSI in the water main. In this case the PRV should be replaced.

A second possibility for the above scenario is high municipal water main pressure with no PRV installed but has a restriction in the water supply cutting back the flow of water. In this case increasing the flow by opening additional faucets will further decrease the pressure.

2.) Another symptom is the pressure remains at 60 PSI. unlesss the water heater is operating. When the water Heater is operating after hot water is used the pressure creeps higher and higher. Many times the T&P valve on the water heater may discharge a small amount of water. This would indicate there is a closed system either from a check valve in the water meter, Back flow preverion device, or a PRV installed. In this case the pressure increase is caused by thermal expansion and a thermal expansion tank should be installed. http://www.plumbingsupply.com/therma...ion-tanks.html



If a thermal expansion tank is installed it may not have a proper air charge in it or, the tank has failed. On the tank there is a schraeder valve like a tire valve. Depress the center of the valve and air should come out. If water comes out, the bladder of the tank has failed and the expansion tank requires replacement. If no water comes out, shut off the main water valve, open a faucet to bleed off the system pressure. Pump air into the tank to match the water system pressure then, reopen the main valve.

[hcj]

valve

The item you describe, especially since it has a PVC pipe to the drain is a trap primer to keep water in the drain. When water is flowing, it diverts a portion into the floor drain to maintain the water seal.

[Redwood]

It could be a few different things.
Pressure relief, and trap primer are possibilities.
A picture would definitely be helpful...

A question for the moderators and admin of the forum...
Why do you have a requirement for 5 posts before a picture can be in the post?
Seems a little silly on a DIYer forum.... JMO