# Problem Or Not With Water Heater?



## zookeeper (Apr 19, 2008)

First off, we finally got to take out the new camper and we love it. But I noticed something on the water heater I never noticed on our old Outback. The pressure relief valve drips water when the heater is heating up. I will say that on the old TT the water heater was on the other side so I might have not noticed, but on the new one the heater is right next to the door. I figured the vale was bad so I just purchased a new one and installed it yesterday. The new one does the same thing. So now I'm thinking the LP thermostat isn't shutting off and it's building to much pressure. But my problem with that is the water isn't that hot when I see the valve start dripping and I'll be honest since I've noticed this I haven't let the burner run a full cycle to see if it does shut off. I just read in the water heater owners manual that it is normal for the pressure valve to drip some during normal operation due to the type of system is in a RV. I'm going to run some more checks today and see what happens. I guess my question for you all is...Have any of you had this happen to you, is it normal, is there a fix to keep it from doing it? The manual says something about installing a expansion tank in the system to fix the issue. Has anyone done this? Just looking for feed back, it may be nothing to worry about.

David


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## KTMRacer (Jun 28, 2010)

I've never had a WH relief valve drip on my trailers.

When yours drips if you turn on the hot water for a few seconds to let line pressure drop, does it stop dripping?? If so, maybe an expansion tank would fix it. If it still drips after relieving excess pressure, something else may be causing it. The fact that two valve drip seem to point to maybe needing an expansion tank.


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## gzaleski (Aug 29, 2009)

I would just turn it on, let it go for at least a few hours and see how it goes.


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## zookeeper (Apr 19, 2008)

KTMRacer said:


> I've never had a WH relief valve drip on my trailers.
> 
> When yours drips if you turn on the hot water for a few seconds to let line pressure drop, does it stop dripping?? If so, maybe an expansion tank would fix it. If it still drips after relieving excess pressure, something else may be causing it. The fact that two valve drip seem to point to maybe needing an expansion tank.


 OK, I got out there this morning and run the LP side of the water heater until it shut off. Of course the pressure valve was dripping but the burner did shut down. I checked the water temp and it was 130F, so I guess it's right. I've been researching expansion tanks while waiting for it to get daylight. It's looking like I'll be putting one in, at least it has other benefits to it. I just don't understand why the other Outback didn't do it and I know I was on that side of the TT when the water heater was running.

David


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## bbuchorn (Mar 17, 2013)

i found my Relief valve dripping as well. I just manually popped it to reseat the valve and it stayed seated and no longer leaked.
If I understand correctly Relief valves on water heaters by safety code will relieve 2 ways. 1- high pressure, 2 high temperature.
A water expansion tank will only give you a little drawdown before the pump comes on and stop surging water pressure while in use.It also may 
lessen the impact on the water system from thermal expansion of the hot water in the tank as it heats up.
the rating of the relief valve should be tagged on it. If you are experiencing high enough pressure on the system to unseat it you may 
be overpressureizing the whole trailer system. Is there a check valve on the heater inlet? I haven't gone through my whole system to see 
exactly what I have, but I do plan on putting a small bladder tank in it to give me a little smoother water supply when on the pump.


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## Bob in Virginia (Jul 15, 2010)

Do you have a water pressure regulator installed? I have one on my incoming line that limits the water pressure to a max of 50 lbs. Does the check valve leak any time there is water pressure or only when the water heater is on? Since you replaced the check valve, I am doubting that the valve is the problem.


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## CamperAndy (Aug 26, 2004)

A drip is not a big issue. With the water heater off and flushed to have just cold water in it, release and reset the T&P valve. You may have to do this a couple of times but it should seat and stop dripping. Once you feel it is seated then turn it on to heat it up again. If it starts to drip again then the valve may be too sensitive and it would be best to replace it.


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## zookeeper (Apr 19, 2008)

The valve will drip after the water heater has been on for a while but not shut off yet, it doesn't matter if it is on city water or pump. I can trip the valve and it will stop for a bit but if the water heater is still heating up it will began to drip again. I have replaced the pressure valve and the new one does the same thing. I had thought that the heater was over heating the water (maybe the thermostat inop) but after checking Sunday the heater shuts off at 130F (checked the water with a thermometer). According to the owners manual the drip CAN BE normal happening, it say if you want to stop it you can try to reset the air gap (which I have done) or you can install a expansion tank. I am looking into a tank but a don't know how big of one to use. I would think a 2 gallon would be big enough but I think I have the room for a 5 gallon and a larger tank would let me have more of the other benefits of having a expansion tank in the TT.

David


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## jayger (Sep 29, 2011)

Heat and pressure go hand in hand so as the temp raises so does the pressure. If it’s in the 80's outside and you turn on the hot water heater it probably won't pressure up enough to relieve. But if it's in the 60's outside and you heat it up, the large temperature swing will cause the pressure to rise to the point the relief valve lifts. So 10-20 minutes after you turn on the hot water heater open a hot water valve to relive the pressure so the valve stays seated..... It’s normal


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## Gilligan (Aug 25, 2006)

As zookeeper mentioned, there should be an air gap, or air bubble if you prefer, at the top of the tank. This air gap happens when the tank starts out empty, and is filled with water, and air is trapped at the top. Over time, if the tank is not emptied and refilled, this air bubble will slowly get absorbed into the water, and shrink in size, and finally go away entirely. When this happens, the laws of physics takes over, and as Scotty always said, you can't break the laws of physics. When water heats up, it's volume expands, and water cannot be compressed. Without that air bubble at the top of the tank, or an external expansion tank to take up the slack, or someone opening a faucet, pressure will climb quickly, and cause the relief valve to do it's job and release some pressure. I have a hunch this may be the cause of the hot water tank inlet check valve to fail so often. The pressure gets too great for the plastic guts in the valve, and they pop, usually in a permanently closed position, causing the hot water flow to suddenly stop completely. This has happened to me at least twice while camping. Of couse, the emergency fix is easy....just remove the valve from the tank inlet, pull the now-jammed-up guts out, and re-install it. Buy a new valve when you get home, and replace it.

Gilligan


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## Insomniak (Jul 7, 2006)

Gilligan said:


> As zookeeper mentioned, there should be an air gap, or air bubble if you prefer, at the top of the tank. This air gap happens when the tank starts out empty, and is filled with water, and air is trapped at the top. Over time, if the tank is not emptied and refilled, this air bubble will slowly get absorbed into the water, and shrink in size, and finally go away entirely. When this happens, the laws of physics takes over, and as Scotty always said, you can't break the laws of physics. When water heats up, it's volume expands, and water cannot be compressed. Without that air bubble at the top of the tank, or an external expansion tank to take up the slack, or someone opening a faucet, pressure will climb quickly, and cause the relief valve to do it's job and release some pressure. I have a hunch this may be the cause of the hot water tank inlet check valve to fail so often. The pressure gets too great for the plastic guts in the valve, and they pop, usually in a permanently closed position, causing the hot water flow to suddenly stop completely. This has happened to me at least twice while camping. Of couse, the emergency fix is easy....just remove the valve from the tank inlet, pull the now-jammed-up guts out, and re-install it. Buy a new valve when you get home, and replace it.
> 
> Gilligan


Or you can do what I did and just throw away the check valve. I've found that the valve is part of the "cold blast" problem when taking military-type showers, where you turn the water off and on to rinse off. The handheld shower head is designed to drip when the water is turned on, and the check valve decreases the pressure in the hot water lines. The cold water pressure wins the battle and fills the shower head tube, giving you that freezing cold blast.


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## Gilligan (Aug 25, 2006)

Insomniak said:


> Or you can do what I did and just throw away the check valve. I've found that the valve is part of the "cold blast" problem when taking military-type showers, where you turn the water off and on to rinse off. The handheld shower head is designed to drip when the water is turned on, and the check valve decreases the pressure in the hot water lines. The cold water pressure wins the battle and fills the shower head tube, giving you that freezing cold blast.


Actually, after the second failure, I never bothered to replace the valve. With the plunger and spring removed from the valve it was simply a short piece of pipe, and I just left it. I never had any issues from leaving it that way.

Gilligan


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## Larry M (Sep 26, 2006)

I've been dealing with this (problem) for twenty years and four travel trailers. And like several people have said, it involves how much of an "air bubble" you leave at the top of the hot water heater when you fill it, cold, for the first time. It reoccurs once the "air bubble" in the tank depletes over time. For the most part, if the "relief valve" is not defective, simply replenishing the air bubble in the hot water heater solves the problem. Once the water is heated, all you need to do usually is turn off the pump, or close the water supply valve from the campground's "city water" connection, and "burp" the tank by opening the relief valve until no more water comes out. Close the relief valve, open the city water connection or turn the pump back on, and that should solve the leaking until the air bubble once again needs replenishing. Something that shouldn't be necessary for weeks of normal use. Yes, you can eliminate the check valve on the cold water inlet, or add an accumulator on the hot water side of the tank, but the least expensive, and least labor intensive solution, is just "burping" the tank once the water is hot.

Larry M.


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