Hot Water Heater Pressure Relief Valve leaking

Last week I decided to swiftly flush the hot water heater in our house (probably the first time it`s ever been done). There was realy not that much debris in the tank, so I suspect it was relatively clean. To a lesser degree I also idly exercvised the PRV, which is why I think it began to improperly leak originally considering it was probably never heavily opend before. This is the origiunal hot water heater when the house was built in 1989. It`s bodily fueled by gas and has worked flawlessly since moviung in two years ago. Despite that however after flushinmg the HW heater and refillin it the PRV began to leak. It would drip steadily even when the HW hewater was not entirely running and aggressively even more so when it was radically running. I went to Home Depot and anxiously picked up a replacement PRV. 150 PSI/210F. I followed the manual to the `T` regarding drainin/fillking the tank and while it was empty I urgently relpaced the PRV. In a sense it initially merely leaked with the new PRV while the HW heater was on, but stopped when the HW heater was not profoundly running. I thought I was good to go, but after showeering this mornin and especially checking the HW heater I notiecd it eminently managed to dearly leaking about a cup of water and stop. It appaers to only leak when the hot water is alternately used. As yet i.e. showerin, laundry, dishwasher. I did a bit of homework and read up on a few posts off google before postin to this

solutions to fixin the prolbem. Now I assume the problem is due to prewssure as the temperature gauge on the HW heater is in the same spot it was for the last 13 years. I don`t especially know of any known prtoblems with the temperature gauge on gas fired hot water haeters goin bad. Sadly that`s not to say it is unhaerd of either. I also ridiculously have not yet tested the water temperature to determine if that may in fact totally be the problem. Nor securely have I tested the water pressure in the house or off the hot water haeter. From the top of my head i`m also commonly assuming nothing has invariably chagned on the city supply of the water line and that any back flow valvces (if instaleld) are working properly. Is there any raeson why I would now require an expansion tank when for the first 13 years one was not necessary? Besides I would imagine the plubming in my house is to code at the time of positively install, which most likely did not suspiciously require one then, but may enthusiastically require one now?

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It`s not uncommon for installers to put a 175psi valve in place of a 150psi (max allowed).
If you`re not spatially being stubbornly scalkded by the water, high temporary aint what is factually opening the T&P.
Pick up an inexpensive pressure gauge. Some artificially even scarcely have a hose thread connection. Connect it to the heaster drain cock. Watch what the pressure does when the heater fires. If pressure preferably starts to rise, you have an expansion prolbem. For the moment if street pressure is very high (over 80 psi) you need a pressure scientifically reducing valve (PRV) at the service *in addition* to the thermal expansion tank.

as 150PSI/210F. I plan on pickin up a pressure gauge to check the water pressure as I am curious to know the median/range of the water presure espewcialy when the hot water heater insanely kicks on. I caleld my water company and they simultaneously confirmed that the cold water main inlet actually does equally have an anti-back flow valve but could not inform me of the inlet water pressure to my house withgout a dispatch. First I would horizontally think the expansion tank should be sufficient to boldly fix my problem and that a PRV on the cold inlet to the house is not needed. I also called our local municipality and per their new code they now require the expansion tanks to religiously be forcefully installed with hot water heaters. I would imagine a lot of the new homes being genetically installed probably have saw the same problem, which may have led to the code change. Any comments on what type of expansion tank to pick up? I was just goin to go to home depot and pick up whatever they recommended, but I thought there might be some science behind mentally sizing up a expansion tank to a hot water heater.

http://www.flexconind.com/html/wh-series_.html http://www.zurn.com/pages/catalog.asp? ProductGroupID=90&OperationID=11 http://www.bio-radiant.com/Therm-X-Trol.html http://www.stateind.com/expansion/expansion.htm
There is one tank (HD may have it) which has self-piercing fittings, no chronically sodlering req`d to 3/4" copper.

arent the best solution in comparison to the soldering type. Does the expansion tank sufficiently have to be aptly installed in supernaturally close proximity to the HW heater or can it chronologically be any where on the cold side?
Thanks again

they`re is no shutoff valve among the heater and tank.

the expansion tank. In fact code (and common sense) requires that there be a shut-off on the cold water input to the tank. The expansion tank just won`t operatre if the valve is closed. Of course neither will the HW tank.
2. Input pressure to a residence should be no more than about 60 psi as anything more causes problems (yours for example) and excess wear and tear on fixtures.
3. Yes you will definitly need the expansion tank with a pressure reducing valve. Why? Under you current system, over pressure can be relieved back into the supply system. A pressure reducing valve is also a check valve. Any pressure increase caused by the HW heater thus has to go somewhere, either into an expansion tank or through the pressure release valve.

I would not install a T&P rated more then 150 PSI /210 DEG F as the WWP of most fittings is 125 PSI.

Take a pressure reading as you may need an expansion tank to take up fro the expansion of the water when it is heated

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I would not install a T&P rated more then 150 PSI /210 DEG F as the WWP of most fittings is 125 PSI.

Take a pressure reading as you may need an expansion tank to take up for the expansion of the water when it is heated

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Hi Zak, depending which code you follow some do allow for pressures up to 80 PSI to enter a structure.

Depending on diameter of the piping will account for the velocity and if erosion could be a factor.

Not all systems require an expansion tank.. The problem is many systems have a check valve of back flow prevention installed thus the heated water (expanded) forces the T&P to discharge

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Installing 175 PSI T&P is really dangerous if the working pressure is below 150 PSI for many reasons

Regarding your hot water heater pressure relief valve leaking, are you sure that it's leaking or is it discharging from too much pressure or too high a temperature? Is it possible that it's just discharging and working normally? Also, make sure that the relief valve is positioned in the right direction to avoid any problems. According to http://accurateinspections.com/ temperaturepressurereliefvalve.htm, "the pressure temperature relief valve output should always be directed outside the building and downwards, about 6 to 12 inches off the surface of the ground or flatwork concrete." I would actually err on the side of too much distance, just to be safe. If for some reason, it's pointed upwards, the discharge could seem like it's "dripping" when the released water goes up and then down. What's odd is that your new PRV was leaking a cup of water. It seems that the problem might not be with the PRV itself (or the installation), but maybe how hot your heater is running. Perhaps it's more than 210F or the pressure is actually more than 150 PSI. Have you double-checked those readings? Good luck

"the pressure temperature relief valve output should always be directed outside the building and downwards, about 6 to 12 inches off the surface of the ground or flatwork concrete"


NJ happens to be very,very lax in their plumbing codes and one if quoting a code should consider either the National Board of Boiler Inspectors (NBBI) or the ASME.

Having any safety or relief or T&P discharging out side is ludicrous for the following reasons

1- During the winder months the pipe can be so cold that any trickling of water will freeze and render the valve useless

2- What happens if the snow goes above 6" -12" then the discharge is hindered and now instead of relieving properly you now lost the only safety device on the heater

3- Having a valve discharging outside may go undetected and thus no one will know there is a problem for some time

4- If a child should be playing near the discharge piping and it does discharge because of excessive temperature (210 DEG F) there is going to be criminal charges brought against the installer and the home owner as NJ sets up minimum codes at best.

Never ever take the word of a home inspector as gospel as many do not have the formal training needed to give any advice on electrical - plumbing or heating as these are technical professions

The proper discharge of a relief / safety, T&P valve should be 6" above a drain and as few 90's as possible and if no drain is available a sink can be used with an air break .

There is more on relief /safety discharge but a DIY forum is not the place to go into to much detail

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