Atwood G6A-8E Hot Water Pressure Relief Valve dripping

[CanoeCanuck]

Good Day Fellow Winnie Owners.
I have a long trip planned with my Winnebago Motorhome this summer so have spent the winter upgrading, renewing many of the systems in my motorhome. I was pretty proud of myself in rebuilding the rusty components of my hot water tank. Replaced the burner tube, thermostat/eco sensors, pressure relief valve, igniter components. Figured I was pretty handy. I had it out a couple times now and have noticed an issue. When hot water tank heats, as it gets close to full temp the pressure relief valve releases a reasonable amount of water. Consistent drip making a small puddle in the base of heater and dripping down the side of camper. Is this normal? My former pressure relief valve was so corroded it probably wouldn’t work no matter what the pressure. Is my new pressure valve working correctly by letting out this water?. Another symptom this week was the drain plug sprung a pinhole leak. I’ve researched this can be a safety mechanism if there is a pressure problem. The tank is heating water to 125 degrees Fahrenheit. It is an Atwood G6A-8E.
Thoughts and advice very much appreciated.
Take care.
Sean

[l1v3fr33ord1]

Sean-

A dripping relief valve can be a sign that the water heater has lost its air gap. Below is a section of an Atwood manual that explains this, and tells how to re-establish the air gap.

I'd buy a couple of the Atwood nylon drain plugs, too. Replace the current plug and keep one as a spare.

If you can't keep the relief valve from dripping, come back here and tell us so we can offer solutions for that.

[Ray,IN]

Buy the same specs safety valve from any hardware store(take the old one) if restoring the air gap fails to solve the drip.


As water heats it expands, without the air gap water must exit somewhere.

[CanoeCanuck]

Thanks for the replies. I’ve done the procedure to re-establish air pocket. I’m still getting about 1/2 cup water coming out of valve during heating. Should I replace the valve or is this considered normal?
Thanks
Sean

[CanoeCanuck]

Hi Ray
I watched the video you posted in another thread on routine maintenance for HWT. It mentions water temp at 140 degrees F. Mine is giving me 125 F. Along with relief valve leak I’m not very happy with my rebuild.
Thoughts.
Sean

[l1v3fr33ord1]

Originally Posted by CanoeCanuck

Thanks for the replies. I’ve done the procedure to re-establish air pocket. I’m still getting about 1/2 cup water coming out of valve during heating. Should I replace the valve or is this considered normal?
Thanks
Sean

It's not normal. I'd replace the relief valve (again). If it still happens, then we'll look at other solutions. I had to implement one on my coach, when the water heater would not maintain an air gap.

It would help to know the pressure in the water system when the relief valve weeps. If there is some place you can get a pressure gauge on the hot side, do so.

On the low-temp issue, there are places that water can mix hot-and-cold. If any of these are mixing, the measured temperature will be lower. So, check the following:

1) Water heater bypass valve (if you have one, move it to the non-bypass position)
2) Outdoor shower (close both hot and cold valve handles)
3) Indoor shower (ditto)
4) Kitchen sink (ditto)

Also, one or both of the water heater check valves can fail, fully-open, partially-open or fully-closed. The symptoms are usually something other than what you describe, but should be checked of the rest of the potential causes listed above does not prove to be the culprit.

[CanoeCanuck]

Thanks for the advice folks. I’ve replaced the pressure relief valve and HWT still leaks on heating. I drained the tank completely so the air pocket must be re-established. I must assume at this point that the dripping on heating is normal. Any last thoughts?

[l1v3fr33ord1]

CanoeCanuck-

A dripping relief valve is not normal.

If you think about it, a drip indicates the relief valve is sensing water pressure around 150 psi. That high a water pressure will cause leaks, sooner or later. A leak may not be in an easy place to find or repair. Or, that high a pressure could cause the nylon drain plug to blow out; it happened to me.

There are ways to bring that pressure back into a reasonable range. Before going down that road, it would be worthwhile to confirm the water pressure when the heater has heated the water to maximum temperature. I did so by buying an inexpensive pressure gauge and attaching it to the water system. You'd do that on the hot water side, as your water heater probably has a cold water inlet check valve.

My post #2 includes the Atwood recommendations for solutions to the disappearing-air gap problem. My coach had that problem, for which I could not find a cause. I chose to install an accumulator (Atwood's second recommendation). I can provide all the part numbers and installation tips should you want to go this route.

[CanoeCanuck]

Ok thank you for the advice. How do you suggest I test the pressure in the tank? Would I put a pressure gauge in the nylon plug hole? Do you know a part number I can order from Amazon? I have a pressure gauge that measures up to 200 PSI that fits a hose spiggot.
Please forward parts/instructions for Accumulator addition.
Thank you.

[l1v3fr33ord1]

CanoeCanuck-

If you already have a garden-hose pressure gauge, then I'd buy an adapter like this one

3/4 inch MHT (Male Hose Thread) to 1/2 inch MIP (Male Iron Pipe) brass adapter fitting

1) Remove the handheld shower head and put the adapter on the hose, followed by the gauge on the adapter.
2) Pressurize the water system and check for leaks, using the cold water valve.
3) Record the pressure.
4) Close the cold water valve.
5) Open the hot water valve.
6) Record the pressure.
7) Start the water heater.
8) Watch the pressure gauge.
9) Once the water heater shuts off, check if the relief valve is dripping.
10) Record the pressure and hot water temperature.

While you're running the test I'll pull together the parts list for an accumulator installation.

[Morich]

I might throw in a couple questions on how the temp was measured and then also ask if this is a normal water heater as found in many RV, why would an accumulator tank be needed on only your RV? Most RV do not require an added accumulator tank!

I might first want to make sure the water temp reading is the actual tank temp, not what you find when it finally reaches a faucet at some point located away from the heater.
A really simple thing might be that the thermostat is not making good solid contact with the metal of the tank as that will skew the reading to make it heat too long and produce too much pressure! Or the button thermostat may simply be defective.

[l1v3fr33ord1]

Some notes:

1) To "Morich's" point, the relief valve is both for over-pressure and over-temperature. So, a drip may mean either.

2) Based on the OP's report of lower-than-expected water temp, I'd say over-pressure is more likely. But, if the outlet check valve is stuck closed (a symptom of which would be no flow), the pressure and temp can be "bottled up" in the water heater.

3) Any testing at or near the relief valve release pressure of 150 psi and temperature of 200/210 deg. Fahrenheit carries a risk of piping/tubing/component/fixture failure, with a risk of flooding and/or scalding. Be careful!

4) I recommend against using the drain plug as a pressure-testing location. It is a "backup" pressure relief point. I would use it if I had no other safe options to measure the pressure.

5) To answer "Morich's" question, adding an accumulator is one of Atwood's suggested fixes for the case where the water heater does not retain its air gap, after repeated attempts. I added one to my coach, for this reason.

6) In for a penny, in for a pound. Any time you modify the water heater plumbing consider removing the check valves and replacing their function with a three-valve bypass system. When I did that I worked the accumulator into the cold-side supply piping at that location. I also added a water heater tank drain, which eliminated the need to remove the drain plug when I emptied the water heater.

7) I found a permanently-installed water system pressure gauge helped to ensure the accumulator was working correctly. A gauge has other uses, too. I installed one in the wet bay.

8) An accumulator uses an air-filled rubber bladder to accommodate expansion in the water system. Place the accumulator where you easily can reach the air valve.

[Morich]

I tend to like going the easy way when looking at things. Most trouble is caused by the easy stuff!
When I look at WHY a heater may have pressure that is anywhere close to making the relief valve vent, The only cause I can see is a defective valve OR thermostat.

I rarely go to videos for info as they are often just so poorly done but there are some which actually are good without all the fluff and nonsense.
I suggest taking a look at how simple it is to go straight to changing the ECO and thermostat if testing is not something you are set up and willing to do.

https://www.youtube.com/watch?v=UkhrbdpHVKA

This video seems to be right on for most of what we need to do on this fix.
There ARE a couple points I might do differently but overall correct.
One is the way he leaves the gasket touching the metal of the burn tube. Why not cut it back to avoid any chance of burning if the fire flares out of the tube?
Second, I would also use some form of corrosion protection on those contacts. He talks about corrosion but does nothing to keep it from happening!
"No-OX a Special Grease" is perfect for this!

My basic, simple thinking is that when we have too much pressure, we have to have too much heat! So I first work on why we have too much heat and THEN look at why too much pressure---if it becomes needed!

[creativepart]

I agree that the thermostat is the most likely culprit. I would revisit that first since it’s inexpensive, easy to replace and a common cause of this issue. But that’s not to say it’s not something much more complex. Just a good idea to start simple, especially if you’ve just replaced the Thermostat. It could be faulty a falter part.

I’d like to know how old the motorhome is, as you described the water heater as having “rusty components.” Also, is the leak coming from the threads of the tank body or from the actual valve? You are using tape or thread seal, right. Just asking because that can be an issue. Can you see the valve dripping?

[Morich]

And that can depend on lots of personal choice type stuff?
Do you want simple and okay with replacing the thermostat without truly knowing it is bad? That's okay for lots of the cheaper things but other folks may not want to spend the extra money if testing and time may tell them if the small items are okay or not?

A thermostat is simply a switch, and we can often test a switch. So if you want to KNOW before replacing the thermostat, take it out and do a test?

Use a meter to test that there is continuity between the two contacts on back. With the thermostat cooled enough to hold, the contacts should be closed to allow heating.
But there should be some info, often printed on the thermostat body, to tell what temp it should reach before the contacts open.
If closed when cool, the only other thing it needs to do is open those contacts when it reaches the correct temp.
One way to test that is to connect the meter leads to the contacts on back, put the thermostat in a pan and heat the water to see if the contacts open when the water reaches near the spec temp!!

Meter, thermometer, some clips to attach the meter, hot water, and a bit of added time may tell you what things are really doing!
With that info, you can then jump in the right direction with far more confidence!

[Morich]

In thinking deeper about this old stunt which I had not used in many, many years, I found I left out some details that are really important.
One biggie is that you can't get a good reading on the meter if the probes or contacts are in the water! Water makes a pretty good conductor, so you have to set it up so the front surface of the thermostat is heated without the back side being wet!
I remember this as something I had to play with a bit at the time to get things to work.

A metal bottle cap off some small jug like a brake fluid can was used to keep the cap where it would be heated while the back contacts were out of the water. It also took a small wood pencil laid across the top of the pan and used to support the probe clips as the water heated.

Sorry about skipping over that. The devil is in the details and I left them off! I last did this test when my kids were in high school and money was pretty tight! Looking at three kids about to start college and now they have their own kids in college, makes the memory a bit lax!

[CanoeCanuck]

Good Evening. I’ve done the test as you’ve suggested. I used the shower faucet rather than the outside shower. Here are the results.
Cold water line 40 PSI
Hot water line 32 PSI
After heating hot water line 141 PSI at 139 degrees F. In testing the temperature the pressure went back to 40 PSI.
I reheated the HWT til shutoff and PSI of hot line 80 PSI at 143 degrees F.
I reheated HWT again and hot line 100PSI.
I left the gauge on the line the whole time to check PSIs and left the line open during heating.
There was still dripping from the relief valve. Probably 1/2 cup water in total.
Hopefully, this gives you enough intel to advise on next step.
Thank you for your help.
Sean

[l1v3fr33ord1]

Sean-

It appears the new thermostat is working well, maintaining outlet temperatures around 140 deg. F.

Maximum expansion occurs when the tank is full of "cold" water. Your maximum pressure of 141 psi reflects this. It would help to know if this is the only time the relief valve weeps. The other recorded pressures are well below the relief valve pressure setting; if the valve is not faulty, it should not weep at those pressures.

Ideally, we want to (somehow) get back to an in-tank air pocket that doesn't disappear, except over a long period- in other words, a "normal" water heater. That way we avoid the complications of adding components. So, I recommend that once more you use the Atwood method listed in post #2 to re-establish the air gap/pocket, and see if that method "sticks" this time. With the pressure gauge installed you'll have more insight into what's going on than you have to date. Note the method says "storage water must be cool" before starting the process. Normally I'd hesitate to ask someone to repeat a seemingly fruitless exercise, but I suggest it this time because I- and perhaps you, as well- would like to be absolutely sure that the accumulator solution was the best path to success (versus installing yet another new relief valve, for instance).

Looking ahead, assuming the Atwood method to re-establish the air gap/pocket fails once more, we should think about the check valves. Here's a review:

1) Winnebago typically installs a check valve on both inlet and outlet. Not all manufacturers do. Some install a check valve only on the outlet.

2) The inlet check valve prevents hot water from going "backwards" into the cold water system, which it would do briefly after the tank heats up, until the pressure in the tank equals the cold water supply pressure. That check valve also prevents the cold water system from experiencing the elevated pressure seen in the water tank as the water heats.

3) The outlet check valve, in concert with the water heater bypass valve, prevents the water heater from filling with anti-freeze when bypassed.

4) Check valves will fail, sometimes intermittently and sometimes permanently. Low or no flow is probably the most common symptom.

Why does this matter? If you don't modify the check valve design, and all the check valves are working perfectly, then the only place to install an accumulator (or additional pressure-relief valve) is on the hot-water side of the piping system. On the other hand, if you replace the check valve and bypass valve with a three-valve bypass system, you can install an accumulator on the cold-side, where it provides additional benefits.

The challenge is that Winnebago often installs the water heater such that it's difficult to access the check valves.

I'll stop at this point, to let you chew on what I've written.

[l1v3fr33ord1]

Sean-

Yours is a 2005 Itasca Spirit 26A, yes?

I just looked at the plumbing diagrams (link here). Please confirm for yourself:

1) No check valve on the cold water inlet
2) Check valve on the hot water outlet
3) Bypass valve and water pump reachable from under the bed or from exterior storage bin, whose door is aft of the water heater

It looks as if you don't have to rework the check valve and bypass valves to install an accumulator on the cold-water side. You may still want to do that work for its own advantages, though.

The lack of a check valve in the cold water inlet means the water pressure inside the water heater is the same as in the cold water piping. Con: If the water heater is 140+ psi, so's the cold water piping (more propensity to leak). Pro: Can install an accumulator on the cold-water side, without having to remove the cold water inlet check valve.

Depending on the room you have under the bed, that would be a logical place to install an accumulator except... for the noise it can make. A better choice might be under one of the two sinks. As I said in a prior post, you'll want to be able to reach the air bladder recharge valve. It's a Schrader valve, such as on a bicycle tire. On my coach, I used a small air hose to bring the recharge valve to a more convenient location.

I'll stop here, again, so you can think through what I've written. Let me know if I've made mistakes on the details of your coach. It would not be the first time I've made mistakes or incorrectly assumed!

[Morich]

A small point but I do not see it mentioned specifically? WHERE is the drip? At the outlet pipe connection on the relief valve or at the threads?

Things are just simply not adding up!
One big question would be how the pressure on a hot and cold line can be different when there is only one pressure source? If you have some level, say 40 PSI, from the hose and test the static pressure on any faucet, they should be the same!
This seems to point to an error reading the pressure. To get a difference in hot and cold pressure, one is not looking at pressure correctly as it has to be static (not flowing) to get the correct pressure.
Many times we see pressure spoken of when it is actually volume, not pressure.
Example? When we say the water pressure is high because the water coming from a hose will shoot farther across the yard. Yes, this is a result of pressure changes but it doesn't mean we can measure pressure this way. Pressure has to be measured without flow to have a firm baseline to talk about.
If not, the pressure on a 4 inch line would be far more than on a 2 inch line and make the whole pressure reading useless! Before saying that pressure on a big line IS higher than on a small line, consider that the readings are often taken at a small Schader valve like a tire valve!

I know that last statement is going to cause a lot of disagreement as I've had this discussion before. The pressure reading on a six inch main coming into a building is exactly the same as the reading on a 1/4 inch line if they are at the same height!

Some where there is a major point missing if the pressure is not the same all through the RV from the water hose to the hot and to the cold.