View Full Version : Water heater woes.

11-29-2008, 05:33 AM
I noticed my water heater was leaking from the overflow pipe coming from the T&P relief valve. I drained and flushed the tank, replaced the valve, actuated it a few times to ensure it was working and overnight I got about 2 tablespoons of water leaking again, what gives??

T&P Valve looking at two sides.

11-29-2008, 05:52 AM
First step would be to get an inexpensive pressure gauge and attach it to a hose bibb or other convenient spot.

The TP valve may just have a bad gasket or seat , OR it may be weeping because it is SUPPOSED to, i.e. your pressure is creeping up over 100 PSI ++. This could be due to a failed pressure regulator on the house, or it could indicate a need for an expansion tank. In the latter case, you would see the pressure creep up any time you run a lot of hot water, causing the heater to turn on to reheat the makeup cold water.

11-29-2008, 06:10 AM
What should the pressure at the hose bib be?? If I need an expansion tank is that something I can do myself??

master plumber mark
11-29-2008, 06:30 AM
either they kicked up the presure in your area
or the water temp where you are has dropped recently...

the thermal expansion tank installs on the incomming line
on your waater heater..

it is somewthing you will probably have to have done.
unless you are handy... and it ususally indicated very high water pressure in your area ...so you might want to get the whole package with a pressure reduceing valve.....

normally this will turn into a debate here....

you might just want to try another t+p valve first before

getting a thermal exp tank and prv valve will run you
somewehre between 350 and 650 depending who you call and what region of the country you are located in..

try another t+p valve

11-29-2008, 08:24 AM
I installed a dual indicator gauge on the hose bib and when I first turned it on, the black dial read 120 and the red was around 70, I turned on a faucet inside and the black dial dropped to 80 then when the faucet was turned off inside the black dial slowly began to rise, currently it is around 90

11-29-2008, 01:36 PM
Two things...water expands when it heats, if there's no place for it to expand into the pressure will increase - often high enough to trip the T&P valve which brings the pressure back below the trip point. And, your plumbing doesn't like really high pressure - hoses can burst, glasses can be shot from your hand when filled under the faucet, but you can get a great shower! Since the copper pipes don't expand much, just a little water expansion can raise the pressure a lot, just like dumping just a little water can bring it back to an acceptable level. Most places highly suggest a PRV if the pressure from the street gets above 80#.

If you have a pressure reduction valve, it sounds like it is shot. Some can be rebuilt, but it is often about the same to just replace it with a new one.

Some water meters have a check valve in them, too. So even if the pressure is normally acceptable, when you use a lot of hot water, replacing it with denser cold, when you heat it up, it expands and can give you grief unless there's an outlet for that increased volume.

If you know how to solder, adding an expansion tank isn't a huge job, and the parts are relatively cheap (in the $50 range for tank, tee, valve, strapping to support it, etc.). A PRV would cost more in parts, if required.

12-02-2008, 05:32 AM
How and where would I install a PRV and is it the same as the T and P relief valve?? Would that stop the leaking from the T and P valve or should I install an expansion tank?

12-02-2008, 05:40 AM
Given the responses, it is time to hire a plumber.

Gary Swart
12-02-2008, 08:02 AM
I agree with Kingsotall on this one. All of us DIYers have a limit in what jobs we should do. We need to recognize our personal limits and not exceed them. The nature of your question indicates your knowledge base on plumbing issues is very limited so professional help is needed.

12-02-2008, 09:40 AM
Your water heater has a temperature and pressure RELIEF valve on it to protect the thing from blowing up - it releases water if it either gets too much pressure or the temperature gets to high.

A PRV pressure relief valve (maybe more correctly called a pressure regulating valve) adjusts the house water pressure down if the incoming pressure from the utility company is too high.

Two very different things.

If you add a PRV, you should also add an expansion tank. If your T&P valve is leaking, it could be defective, the pressure could be too high, the WH could be too hot, or you need to replace or install an expansion tank.

12-02-2008, 04:01 PM
I installed a pressure gauge on the drain spiggot on the water heater, when the pressure spiked to around 140-143 that is when the relief valve opened and the water ported out of the CPVC, yes I sat there and watched, the nominal pressure seemd to be running from 65 to 85. I read about a regulator you attach to your toilet tank made by WATTS, any opinions on this or should I just install an expansion tank?

12-02-2008, 05:41 PM
Install an expansion tank...

Gary Swart
12-02-2008, 10:20 PM
It's this simple. If you have a PRV you must also have an expansion tank. Without the expansion tank, it takes just a few seconds after the water heater starts to heat for the pressure to rise to the point where the T/P valve will open. That's what it is supposed to do to prevent your water heater from exploding. (For real) The PRV is usually installed right after the water supply enters the house. The expansion tank is placed in the supply line between the water heater and the PRV. It's not especially hard to do IF you have some basic knowledge of plumbing and basic skills such as soldering. If you don't have those attributes, then call a plumber.

12-03-2008, 02:14 AM
Does anyone have any opinions on the regulator made by Watts the goes in the tank of a toilet??

12-03-2008, 07:18 AM
???? post the part number or, a link to it on the Watts website.
I'm not sure what you are looking at. but it probably is not the right device for your application.

12-03-2008, 10:44 AM


HOME >Water Safety & Flow Control >Water Safety & Flow Control >Water Heater Installation Products >Relief Valves/Ball Valves >Governor 80

Governor 80
Ball Cock and Thermal Expansion Relief Valve
Size(s) : 10, 11-1/2, and 12-1/2 in. (250, 292, or 318mm)

Series Governor 80 Ball Cock and Thermal Expansion Relief Valves are triple-function devices: a toilet tank ball cock, an anti-siphon backflow preventer and a thermal expansion pressure relief valve. The Governor 80 limits the domestic water system's preset static pressure, protects the temperature and pressure relief valve on the water heater, reduces the requirement for a thermal expansion tank or an auxiliary relief valve and prevents backflow from water closets. Relief Valve Set At: 80psi.

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Models/UPC Codes
UPC Part # Description
098268921762 0721505 GOV 80 M1-10
098268921779 0721506 GOV 80 M1-11.5
098268921786 0721507 GOV 80 M1-12.5
098268921809 0721509 GOV 80 M1-10 100
098268921816 0721510 GOV 80 M1-11.5 100
098268921823 0721511 GOV 80 M1-12.5 100
098268921830 0721512 GOV 80 M1-10 125
098268921847 0721513 GOV 80 M1-11.5 125
098268921854 0721514 GOV 80 M1-12.5 125

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Danger Scalding Lurks!
Every year, thousands of people in the United States suffer serious thermal shock or scalding injuries in their bathtubs, sinks and showers.