Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×

Thread Tools Search this Thread Display Modes
Old 06-14-2023, 06:35 PM   #21
Winnebago Master
Ray,IN's Avatar
Join Date: Aug 2001
Location: North America somewhere
Posts: 2,207
Originally Posted by Morich View Post
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.
That is a very important point, I've been thinking of that throughout this thread. This is a study in hydraulics, and it's been so long I can't even remember the courses I took 58 years ago.
There is no pressure-activated relief valve on the tank exit plumbing or no cold water would flow when the water heater is not operating.
The only logical explanation IMO is; The over-pressure, over-temp, valve is under-rated, and not OEM.

What we need is a hydraulics expert here.
2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member,FMCA. "We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert the Constitution." Abraham Lincoln
Ray,IN is offline   Reply With Quote
Old 06-14-2023, 07:19 PM   #22
Winnebago Master
Join Date: Nov 2018
Location: Pflugerville/Austin, Tx
Posts: 7,838
Originally Posted by Ray,IN View Post
That is a very important point, I've been thinking of that throughout this thread. This is a study in hydraulics, and it's been so long I can't even remember the courses I took 58 years ago.
There is no pressure-activated relief valve on the tank exit plumbing or no cold water would flow when the water heater is not operating.
The only logical explanation IMO is; The over-pressure, over-temp, valve is under-rated, and not OEM.

What we need is a hydraulics expert here.
My thought was more basic as there may be two places it can leak. One is the point most of us have been thinking and relates to the valve sealing.
But that has not actually been stated or questioned as far as I see. So if the OP was not telling us the leak is at the threads where it screws in, that would really change the story a whole bunch!

It's been mentioned that the tank was old, corroded or rusty? What if they are not getting us the full story and it is the threads leaking due to a big chunk of rusty threads missing?

I admit that seems paranoid on asking such a basic question but I do find missing the important info happens all the time around here!

That combined with two different pressure readings on the same system seems to show we may not be getting the totally correct info??
A difference of 32 and 40 PSI between hot and cold makes me question how these readings are found.
Is the pressure from a source which is consistent or is it possibly from a well system with a pressure tank that would explain the different pressures at different times?

These are often kind of funky little meters and a small difference can be normal but a difference of 8 PSI on 32PSI is somewhere around 25 % and that is NOT an acceptable reading!
Why no RV year, make and floorplan on MY signature as we suggest for others?
I currently DO NOT have one!
Morich is offline   Reply With Quote
Old 06-15-2023, 12:02 AM   #23
Winnebago Watcher
Join Date: Jan 2023
Posts: 4
Accept the drip but divert it.

Originally Posted by l1v3fr33ord1 View Post

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.
Take the above as the Gospel!
I have the same ďproblemĒ and made the same analysis. I did eliminate the outlet check valve, installing manual valves instead, but for the reason of reliability.
Decided that I liked the fact that the pressure relief was sensitive. What to do about the water? Others mentioned hose adapters in their threads for measuring pressure. I used one and cannibalized a bicycle tire fill hose to lead the water out of the MH. Just make sure that the hose is screwed on properly, so that the relief products have a way out. Thest it by opening the lever on the valve.
Bosse is offline   Reply With Quote
Old 06-19-2023, 02:03 AM   #24
Winnebago Camper
Join Date: Jul 2021
Posts: 20
Good Evening.
So, an update on my HWT. Iíve taken your comments and tried to accommodate all of them. Iíve replaced the thermostat again. This time I ordered the part from Atwood rather than the Dreyoo aftermarket one from Amazon. The HWT still leaks from pressure relief valve when heating cold water. Temperature gets to 140 degrees F and pressure on the hot water line in shower is about 140 PSI. After relieving the pressure it hovers around 80PSI with each reheat. I ran the shower so the HWT would have to reheat somewhat. Minimal water from PRValve and all other reheats release no water from PRV. The high pressure and leak seems to be happening only with quite cool water. I suppose this is how it is designed to work releasing some of the pent up pressure due to big change in water temperature.
You are correct that I have an Itasca Spirit. There is only the HWT shutoff/by pass valve and it is set correctly. All other valves are working correctly.
With respect to measuring the pressures, Iím using a 200 PSI gauge that I used on hose bib to measure house pressure. I did mention different pressures for hot and cold lines and made the mistake of taking gauge off between hot and cold sides to relieve the pressure to get new reading. I was unaware this would relieve pressure from both sides. If I leave it connected and just change hot/cold tap openings pressure stays consistent.
Thank you for your advice til now. Having replaced the PRV twice and thermostat twice I must conclude it is working as designed.
CanoeCanuck is offline   Reply With Quote
Old 06-19-2023, 09:21 AM   #25
Just Trying to Help
Join Date: Aug 2015
Posts: 531

Thanks for the additional testing and the concise write-up!

The cold water ===> high pressure is the result you'd expect. I conclude that the water heater is not maintaining the air gap/pocket. It should, but it isn't. If it did, the air gap/pocket would get smaller as the water heated, but without lifting the pressure relief valve at/near 150 psi.

At this point you may feel like living with the weeping, and I wouldn't blame you. You can only devote so much effort over time to a problem. Allowing the weeping to continue has two drawbacks:

1) The mess of having water coming from the valve (could mitigate with the hose idea in a prior post)

2) Long-term, a water system pressure of 140+ psi is not OK for the piping (can mitigate by releasing a small amount of pressure after cold-water reheat)

If you decide to proceed with an accumulator solution to eliminate the weeping, let us know here, or send me a private message. I can provide details either way.
2008 Holiday Rambler Admiral 30PDD (Ford F-53 chassis)
2009 Honda Fit Sport
l1v3fr33ord1 is offline   Reply With Quote

atwood, water

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Propane Vapor Relief by Emergency Shutoff Valve Going Off oceanside Plumbing | Systems and Fixtures 14 07-27-2021 07:25 PM
NO HOT WATER! Water back flow preventer valve failure. What I found. Topsail Plumbing | Systems and Fixtures 9 07-09-2019 08:03 AM
Hot Water Heater Pressure Relief Valve MutinyGuy Electrical | Charging, Solar and Electronics 12 01-14-2015 07:52 PM
Water Heater Pressure Relief Valve traveler of california Plumbing | Systems and Fixtures 7 11-30-2010 08:41 AM

» Featured Campgrounds

Reviews provided by


This website is not affiliated with or endorsed by Winnebago Industries or any of its affiliates. This is an independent, unofficial site.

All times are GMT -6. The time now is 12:16 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.