Hot water heater pressure relief valve

[BatDude]

New lesson for me…We have been turning off our water heater after each use in order to conserve propane. Our new Escape has the 110 VAC/propane 6-gallon water heater. Temp is factory preset so really hot.

We have been camping in arears with dirt/grass sites like the 31 days at Jekyll Island so did not notice what I perceived a few days ago as a water issue. Out Topsail State Park in Florida was on a nice concrete pad, very level. When disconnecting I noted a small wet area under the water heater area. Me thinks YIKES!

So, I kept an eye on this and at first assumed that I had not used sufficient Teflon tape on the anode rod I removed to drain the tank to avoid freezing before we departed on our trip. So, I removed/replaced the anode again with an extra layer of tape this time. Although I used the standard amount the first time.
For the next two nights we stayed single nights on our way west at places with concrete pad. Again, I could see a wet spot under the water heater. When I opened the water heater hatch cover, I could see the water was dripping from the pressure relief valve. Oops.
Quick call to Escape and Dave the parts/serv ice guy called back about an hour later. Ahem …after I rushed to an RV supply store 5 miles away from tonight’s one-night park and stop and spent $29 for a replacement.
Dave called back just as I was about to remove the pressure relief value on the unit and educated me that these water heaters will always drip to relieve pressure when the heater is continually turned on and off. Better to leave it on the entire time (electric). Every time one disconnects and re-connects some air gets into the system. It expands as the water is heated so pressure is relieved by the safety value.
Lesson learned from now on when we connect, I will use the 110 VAC to heat the water and leave it on all night.
The assumption is that for a longer time it is on it will only leak at first heat up and expansion,
Never noted that issue with eh smaller Scamp propane heater, but apparently normal for the 6 gal Suburban gas/electric heater.

Every day is a new learning event!


Cheers,
Bat Dude

[Raspy]

Every time the water heater warms up from ambient temp to hot water temp, the water expands and causes a pressure rise in the system. This can easily push the pressure up from about 40 to 100 and make it leak. The leak is coming from the safety relief that is simply doing it's job. BTW, do not ever screw a plug into the relief to stop the leaking!

The normal pressure rise puts a lot of stress on the whole system.

The fix is to add an accumulator. It has a trapped air space that will compress as the water expends and reduce the pressure rise.

Leaving the water heater on is not the fix. You still have temperature, and the resultant pressure spikes. Every time you take a shower, for instance, the water heater is mostly cool and comes back up to temp. Every time the heater is fired up, and there is no water running at the sink, the pressure is rising toward the pop point of the relief. It makes no difference whether you are heating the water with gas or electric. And the thermostats on either one don't really hold the water at a constant temperature.

The addition of an accumulator is easy and every pressure water system with a water heater should have one.

[cpaharley2008]

I have only had propane only water heaters in my 4 Escapes and never had this issue...

[Glenn Baglo]

The solution is to consider the drip to be "no problem".

[Raspy]

Originally Posted by BatDude

Every time one disconnects and re-connects some air gets into the system. It expands as the water is heated so pressure is relieved by the safety value.

Bat Dude

This is not what is happening. Air is compressible and water is not. Both water and air expand when heated. When the system has no air in it, the expansion of the water has no place to go and the pressure rises sharply. If there is air in the system, it will compress as the water expands and reduce the pressure rise. This is the function of the accumulator tank; to always provide a place for the water to expand into by providing a trapped air volume that is always there. So, if you get some air in the system accidentally while re-connecting, it actually helps stabilize the pressure when the water heater comes on. Not a problem.

[Raspy]

Originally Posted by Glenn Baglo

The solution is to consider the drip to be "no problem".

Except that the pressure in the system will keep cycling to a very high number that may cause an early failure somewhere in a faucet, the water heater or a plastic fitting. Pressure relief valves that continuously get cycled, or "leak" will eventually not re-seal and will have to be replaced.

It's much better to set it up right with an accumulator. I know a lot of manufacturers seem to not provide them from the factory, but that is a bad practice and is done, probably just to save a few bucks.

[Glenn Baglo]

I only turn the water heater on once or twice a day for half an hour, prior to doing dishes, unless someone is going to take a shower. Gets shut off after shower. Stays hot for quite a long time.

[Raspy]

If you are interested in what happens, attach a pressure gauge to the system, turn on the pump to bring the pressure up to normal with the water heater off. Blow out any air in the system. Then start the water heater and watch the pressure without turning on a faucet. On a gas water heater the pressure will be near 100 within 15 minutes, unless it has an accumulator.

An easy way to do this is at the anode/drain fitting on the water heater, but anywhere downstream of the pump is fine.

I hear a lot of talk about putting a regulator on the water supply at parks with unknown pressure. Some parks even warn of high pressure. So, people are concerned about pressure. But nobody thinks about it after the regulator, during water heater firing. A good place for a pressure gauge is right after the regulator, on the hose, if you are running on city pressure. If running on the tank, the best place is on the water heater drain fitting.

[Borrego Dave]

Bat Dude, you say it's preset for temp, does that mean there is no adjustment you can make for temps?

[Ken in Pa]

We have had this drip on both our Scamps.

[ZachO]

I also turn my water heater off when I'm not using, but mine is also propane. I experimented until I found the heat setting that allows me to use straight hot water at a temp comfortable for me. This way I'm not wasting water when I shower (the only time I use the water heater; I heat water on the stove for dishes), messing with hot/cold to find the right temp. I just turn on the hot.

[gordon2]

Originally Posted by Raspy

...
The fix is to add an accumulator...

Originally Posted by Glenn Baglo

The solution is to consider the drip to be "no problem".

Ha you are both wrong.. the fix and solution is to get rid of the silly water heater!

OK OK.. I'm (sort of) jesting there. But for a few reasons removing the water heater was my choice. It is not for everyone and almost surely not for anyone who has a good shower in their camper, a good supply of water, and actually prefers the camper shower.

And I would never argue that the accumulator solution is not a good one. But for me at least, I have gravitated toward making my camper simpler in many respects. How much more plumbing and "stuff" do you want in a camper? That of course is a personal decision.. YMMV.

Speaking of simpler.. How about just opening the hot faucet to relieve the pressure and stop the drip at the safety valve? Especially if the water heater is not used often.

[Darral T.]

If I get rid of my water heater, it will be draggin my Scamp along behind it!

I've had my Scamp for 9 yrs now. Last year, I DID develop a slight dripping from the pressure relief valve. And NO, it did NOT occur from leaving it off overnight. I leave my "HottRod" running on electricity continuously. If I'm off the "grid" with a generator, I turn all of it off during the day, turn on gas to heat it back up at night, then turn it over to electric and off with the gas for the remainder of night.

So where did my "leak" come from and/or how did it start? SEALING. Yes, I read up on it (My water heater is an Atwood [alum tank] btw). AFTER turning off the water.....relieving the pressure and making sure the water was low enough or what ever to not run through the PR valve, I sprayed it with "silicone" lubricant and worked it vigorously in and out.

Never had another leak since and I TOO was about to replace the valve!! But in all reality, they say a drip or two is NOT uncommon- especially as said when it's going through the change from cold to hot etc. But again, until this one incident last year, it had never done it previously.

Love my bathroom, shower, hot water. If it goes my Scamp goes. I'm not too lazy to deal with it.

[gordon2]

Originally Posted by Darral T.

..
Love my bathroom, shower, hot water. If it goes my Scamp goes. I'm not too lazy to deal with it.

Just for the record.. its not a matter of being lazy. In fact, I put a lot of effort into maintenance. The way I use my camper meant I almost never needed the shower, and therefore the almost never needed the water heater. When the supply valve developed a leak and I realized that the only time I fired up the water heater was to test it, it just made more sense for me to reclaim the wasted space. YMMV

On the other hand, if I used the water heater a lot, or full time, I might add a accumulator. I also would look into one to deal with the pump cycling.

[Darral T.]

Actually...I was just making a statement. Hmmm..you took it personally. Picking really... as I figured it would rattle your chain but I know from experience from seeing what you post on here you're not lazy.

In total reality, if it wasnt for the wife, I could suffice with a porta-potty (late night trips) and running some water through my coffee-maker for hot water when I wasnt using their facilities . Without the Scamp bathroom- the CURRENT reality is, she wont go!

[QUOTE=gordon2;730034]Just for the record.. its not a matter of being lazy.

[gordon2]

Originally Posted by Darral T.

..
In total reality, if it wasnt for the wife, ...

So true.. when it comes to YMMV, there might be nothing that varies your "mileage" more than the other half.

[Bob_SWCO]

Be aware that an accumulator installed downstream of the water pump, and upstream of the water heater, will not alleviate high pressure in the WH if there is a check valve installed on the cold water inlet of the WH. Installation of a check valve in this location is standard for current Escape trailers.

We have a 2017 Escape 5.0 TA (display), purchased new in July 2018. I observed that the relief valve vented what I thought was an excessive amount of water every time the WH runs a heat cycle.

After completing the following tests, I do not draw any conclusions about what modifications makes sense (I expect everyone will have their own opinion), or even what is “normal” in terms of WH relief valve venting. I am just reporting the results of my narrowly focused tests.

Not realizing that ETI had installed a check valve at the cold water inlet of the water heater, I installed a 2 gallon accumulator (pressure tank w/ air bladder) between the water pump and the WH. See post #155 on page 16 of this thread [http://www.escapeforum.org/forums/f8...-7807-19.html] for photos. Because the check valve isolates the cold water side of the plumbing system from hot water expansion, the accumulator had no effect on the relief valve venting (my primary reason for installing the accumulator).

I wanted: 1.) to quantify the amount of water venting from the water heater’s temperature and pressure relief valve; and to determine 2.) how hot the water was getting; and 3.) the pressures developed at the top of the heat cycle. To do this I removed the relief valve from the WH and installed a ¾” diameter threaded steel nipple with a ¾” threaded steel cross on the outboard end of the nipple. See photos. At the end of the cross I reinstalled the relief valve. In one side of the cross I installed a water temperature gauge, in the other side a pressure gauge. I then ran several tests with electric as the WH power source and one with propane as the heat source. Presumably, removing the relief valve to install the nipple, cross, etc., established an air pocket in the WH before the test began. If so, it did not prevent our relief valve from venting due to high pressure during the heat cycle.

Relating to the WH, in general I found:
•using electricity our WH heats up to 120-123° F, with propane the WH cycled off at 130° F;
•our relief valve begins to drip around 138-140 PSI, and as temps drop it seals around 135 PSI;
•water pressure peaked at 146 PSI or less, the valve vented in drips at up to 100-110 drops/minute.

According to published data, our ETI supplied Shurflo 4008-101-A65 water pump is designed to come on at 40 PSI and turn off at 60 PSI. For our unit, the water pump-on/off-settings have a spread of approximately 15-16 PSI, for example: on at 40 PSI, off at 56 PSI; or on at 44 PSI, off at 59 PSI. The actual engagement/disengagement points vary (perhaps in response to temperature?). Without the 2 gallon accumulator (I can isolate it by turning a ball valve) in use, just an ounce or so of water use triggers the pump. With the 2 gallon accumulator (air pressurized to 37 PSI) in the system, starting with the water pressure run to the “top” (56-59 PSI), I can run 44 oz. of water before the pressure drops enough to trigger the water pump. For example: starting at 59 PSI, 16 oz. of water run drops PSI to 51; 32 oz. of water run = 47 PSI; 44 oz. of water run = 44 PSI.

When I vented 16+ oz. of water from a hot water faucet, after the WH heat cycle had begun, the accumulator kept the pump from coming on and the pressure relief valve did not vent because the pressure in the hot water side of the plumbing has been reduced.

Possible alternative modifications include plumbing the accumulator into the hot water side of the system. The unit I bought is rated for this application, but this would not prevent the pump from coming on whenever the toilet is flushed or a cup of water is drawn, a benefit we currently enjoy.

Another option is to relocate the current brass check valve further upstream, using pex adapters to install it between the accumulator and the pump. This would likely prevent the relief valve from opening when using the WH, while protecting the weak check valve integral to the pump. It might lead to leaking from the toilet when the WH runs, though a two gallon accumulator might keep the pressure low enough to prevent this. Of course one could just disregard the mud puddle that develops under the WH when it is used and think about something else.

A detailed chart of observed pressures at set time intervals, and photos of the temporarily installed test plumbing, are available at post #187 of the link posted above.

[Raspy]

Bob, Excellent report.

Not sure why a check is needed on the inlet side of the water heater unless maybe to prevent temp fluctuations at the faucet or when the shower is running and the kitchen faucet is turned on. Placing it immediately after the water heater would solve the accumulator location problems and might also address fluctuating temp problem, if that is the problem.

That is what I would try first. Or, two accumulators could be installed, one on the cold, after the pump and one on the hot, after the water heater, but that all seems like too many parts.

Remember too, accumulators do not need to be exposed to the hot water as they can be attached on a long pigtail that is teed into the line, and then placed anywhere that is convenient for mounting. it sounds like you used a conventional domestic hot water accumulator designed for use in houses. These are very good and quite large. Nothing wrong with them at all and they are deigned to stand hot water. The standard units supplied for trailers are just barely big enough.

Your pressure reading of up to about 140 PSI is completely unacceptable to me. That is VERY high pressure and could easily lead to a failure. Yikes! Good job on getting it under control.

Now, here is a little trick you might find useful. If your check valve is a typical swing check with a brass flap inside, just drill a very small hole through it to, in affect, make it a fast one way-slow the other way valve. This will alleviate the pressure problem, and will still act as a check, for the most part.

[Bob_SWCO]

Originally Posted by Raspy

Not sure why a check is needed on the inlet side of the water heater...

Reace (Escape Trailers) told me they started installing check valves on the inlet side of the water heaters primarily to protect the weak check valves that are integral to the water pumps they use. Beyond damaging the check valves in the pumps, he also said owners sometimes experienced leaks from the toilet inlet valves when the WH cycle raised water pressure throughout the trailer. I have read posts from owners who experienced other cold-water-side leaks (under sink faucet connections, etc.), when they did not have a check valve isolating the cold water supply side from the WH.

[BatDude]

Phew survived San Antonio I-10 and now very comfortably sitting at Sonora Caverns RV park. AWESOME!!!!!!!!!!!!!


Houston was almost "white knuckled" drive though.
We did reconnect the Escape rear camera and traveling through SA was not too bad as we could see folks rushing up our tail and about to pass before we changed lanes.


OK back to water heaters... Borrego Dave...Yep the Suburbiton gas/electric has a factory preset temp. No consumer adjustment.



The other reply was to "ignore it" and that is what Escape told me.
The warranty is 2 years so it is logged into the Escape system so if it failed will be covered.


Eeee down to high 40s already tonight.
So what! It is dark and quiet here.


Thank you RVPAKY for helping us finding this slot.


On a technical note.... careful you may face MEGO


My Eyes Glaze Over....

Poop.... my bat recording device has a dead microphone. I loaned it to one of eh a PhD. students I work with. She deployed it in Costa Rica. got some awesome data. But for some reason the mic is now dead so I can not record bats now.


Now I must shell out a couple of hundred $ to replace it. Not an issue as I am happy to support the next generation to carry on the bat conservation work.


We lose the bat we lose the lungs of the planet! If you enjoy getting up every morning and breathing you enjoy the O2 in the air.



OK off my soap box.


At some point I will post a trip report stop by stop as DW has documented each stop.


Cheers all,
Bat Dude & family pix later