Got a question about a water heater TPR valve. I have a 40 gallon electric water heater with an expansion tank installed. Lately after running the hot water for a while, i can hear water dripping on the vapor barrier in the crawlspace. The TPR vavle was changed out about a year ago for the same problem. The discharge pipe just goes through the floor. I was wondering if this is common, ( leaking valve) can i just pipe it on out from under the house so as not to have a moisture issue, or is it possible that valve is bad again. Thanks
In my experience, not only is the TPR valve bad, the pressure regulator is bad which damaged the TPR valve not once, but twice. I am not a plumber…this opinion is from personal experience.
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Agree with Brian, and there may/could also be a problem with the expansion tank!
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I was wondering about the expansion tank myself. Its been on there for about fifteen years. Do they go bad? Would i see a difference in water pressure at the faucets if pressure regulator was going bad
Yup, that is one symptom. Go turn on a couple of faucets then flush the toilet. If the flow reduces at the sinks, it is an indicator that the pressure regulator may be faulty. Or as JJ stated, thermal expansion tank or both. You are going to need a plumber.
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No significant pressure drop if any. Im leaning towards expansion tank.
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Okay, go for it. Let us know how it turns out.
After doing a little investigating, i found out that if you push the shraider valve on bottom of the tank and get water instead if air, usually a indication of a bad tank. Well i got nothing but water. Tank is at least fifteen yrs old.
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A nonevasive way to inspect an expansion tank is to tap on the bottom of the tank, It should sound hollow. If you hear a solid sound, it is full of water, and the tank is bad.
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Thanks for the info from everyone.
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Discharge pipe goes directly through the floor…and into the crawlspace?
That’s a no-no, no?
If you’re going to correct it, you may as well make it compliant.
Some reference: (Note #5 & #7)
Ref IPC504.6 Requirements for discharge piping.
The discharge piping serving a pressure relief valve, temperature relief valve or combination thereof shall:
1.Not be directly connected to the drainage system.
2.Discharge through an air gap located in the same room as the water heater.
3.Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap.
4.Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
5.Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.
6.Discharge in a manner that does not cause personal injury or structural damage.
7.Discharge to a termination point that is readily observable by the building occupants.
8.Not be trapped.
9.Be installed so as to flow by gravity.
10.Terminate not more than 6 inches (152 mm) above and not less than two times the discharge pipe diameter above the floor or flood level rim of the waste receptor.
11.Not have a threaded connection at the end of such piping.
12.Not have valves or tee fittings.
13.Be constructed of those materials listed in Section 605.4 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.(ex: copper, galvanized steel, CPVC, and PEX or PE-RT are all approved. PVC is not approved, because it is not rated for transporting hot water).
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Like somebody else said…a leaky TPR valve could be a bad valve or bad expansion tank and those are the most common culprits. However…when I talk to plumbers in casual conversation, they never say they adjust the expansion tank. So if it’s not adjusted right it won’t perform correctly and maybe that could cause the TPR valve to leak too. At any rate I think the expansion tank has to be adjusted to the same average pressure as the house.
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Exactly my thought, especially since its a recurring problem.
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Feel it.
Heavy as hell? Water only? Bad.
Light and makes a bell sound when tapped? Good.
It has a rubber bladder inside, destined to fail. Doubly so if you change the anode rods on your water heater, and thus get more life out of the water heater. Normally when then heater tank goes bad, the expansion tank gets changed out at the same time and both become scrap metal. 15 years is a long time for a modern expansion tank.
Another outside contributing factor can be deterioration in the tank, leading to debris or scale on the TPR valve.
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Will the real plumber please stand up!
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Pretty certain its the pressure tank. Tapping on it sounds solid, and pushing the valve sprays water. I didnt really know those things went bad, but makes sense being at least 15 yrs old. Maybe older.
Tap on the side of the tank expansion with a solid object (screwdriver handle works well) Tapping near the bottom should sound solid and near the top should sound hollow. If it is the same the tank is full of water and needs to be replaced.
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The leaking TPR valve may also be a symptom of a major issue with the water heater, especially if it is an old unit. Call a plumber.
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If the expansion tank sprays water when you push the Schrader valve, the tank is toast and needs to be replaced.
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