Hot Water Back Flow Valve - Montana Owners Club

berridge · 01-16-2008, 04:03 AM

When my hot water runs there is a rattle like noise which I think is the one way valve. I was told that it is located at the back of the hot water tank on the COLD water inlet. It is impossible to determine where it is by listening as I can't pinpoint its source. I know that some other makes have the valve on the hot water outlet. Can anyone give me direction as to its location?

hazmic · 01-16-2008, 04:21 AM

Should be on the HOT water outlet. I think it's plastic and if rattling I would replace it. Be sure to get a metal one.

SlickWillie · 01-16-2008, 06:15 AM

Try this thread. I think that might be on the cold inlet side, but regardless, the thread links a picture.

OntMont · 01-16-2008, 07:36 AM

If it is like mine, it is on the back (opposite end to the outside grill), you probably will need a 1" deep socket to remove it. I have a spare on hand (just in case) and it is brass with plastic parts inside. I'm pretty sure that it is on the HW outlet pipe.

snfexpress · 01-16-2008, 12:46 PM

I posted some pictures in this thread:

http://www.montanaowners.com/forums/...ad.php?t=25288

berridge · 01-16-2008, 02:49 PM

Thanks for the info re the back flow valve. The dealer service people told me it was on the cold water inlet so as to prevent hot water from flowing back into the cold water line when the cold water taps are opened and the pressure drops in the system. This reasoning also appears on the RV Doctor area of the Camping World site. I'll find the answer as soon as I get around to climbing into the pit with my wrench and will report the result. Both the fittings look the same so one will have to be removed to find out.

RKassl · 01-18-2008, 01:00 AM

Where is this valve located on a 2005 2955RL?

Thanks

EagleRunner · 01-20-2008, 04:04 PM

Bob,
Same place as shown on the pictures from snfexpress. That is, on the top back of the water heater. The access door, right of the range below the second drawer, should provide immediate access to this valve.

Tom

Dave e Victoria · 01-21-2008, 02:45 AM

HMMM, except for finding it, I don't think it makes any difference if it is on the hot or cold side of the tank. It would serve the same function as you cannot stretch or compress water. Having said that, if it has plastic parts, it might live longer on the cold side.
Dave

SlickWillie · 01-21-2008, 02:59 AM

Quote:

quote:Originally posted by Dave e Victoria

HMMM, except for finding it, I don't think it makes any difference if it is on the hot or cold side of the tank. It would serve the same function as you cannot stretch or compress water. Having said that, if it has plastic parts, it might live longer on the cold side.
Dave

Does water not expand when heated?

H. John Kohl · 01-21-2008, 04:10 AM

Also Cold sinks and hot rises to the top. So that would be the reason for putting the check valve at the hot discharge point.
Cheers,

SlickWillie · 01-21-2008, 04:51 AM

Quote:

quote:Originally posted by H. John Kohl

Also Cold sinks and hot rises to the top. So that would be the reason for putting the check valve at the hot discharge point.
Cheers,

John, not sure I follow your line of thought. How would check location have any affect on the water in the tank? Not being argumentative, I just don't follow that.

I have never looked at the check valve (hope I don't have to). My idea that it might have been on the cold side was merely from correspondence with Suburban regarding safety valve weeping. They said the hot water heater is a closed system, thus over pressuring to the point of the safety weeping. Solution was to open a hot water faucet to relieve the pressure. This was the source of my reasoning. If the check is not on the cold side, the whole RV plumbing is subjected to pressure exceeding 150 PSI, the set point of the safety valve.

I did a little more research, and found that the location of the check valve may be on the hot side, but merely for the purpose of bypassing the heater with only one manual valve. Hmmm, I think Suburban may have been BS'ing me. One of these days I am going to put a pressure gauge on both cold and hot sides and just see what the pressure is when that dang safety weeps.

H. John Kohl · 01-21-2008, 05:31 AM

Here was my thought at the time of posting.
With the check valve at the top it prevents the hot water from leaving (rising) from the tank into the line and being replaced with colder water or at least trying to heat the water line too. More efficient.
If hot water rises then the colder water in the line will sink to the bottom.
Thanks for asking the clarification.

Reading your post it think the winterization concept is probably a better response.
Cheers,

sreigle · 01-21-2008, 12:27 PM

I had to replace that valve on our prior Montana's water heater. It was on the cold water inlet on that one. The same valve on the water heater in this Montana is "singing." I've purchased a replacement and will replace it soon. It also is on the cold water side. I'm not aware of any on the hot water side but maybe some are. Mine have been on the cold side.

snfexpress · 01-21-2008, 03:02 PM

Steve,

I am beginning to think that mine was installed on the hot water side, in error. Maybe this is why when trailering and obviously not hooked up to water, my City inlet leaks?

SlickWillie · 01-22-2008, 02:49 AM

Quote:

quote:Originally posted by snfexpress

Steve,

I am beginning to think that mine was installed on the hot water side, in error. Maybe this is why when trailering and obviously not hooked up to water, my City inlet leaks?

There should be a check there also. I had a TT before the Mountaineer, and there was no check in the city water connection. I tried to use the water pump, and went outside, and there was a steady stream of water coming from the city connection. I replaced the connector, and on inspection, it looked as if the check was left out from the factory.

When the weather gets a little better here, I am going to crawl in the basement and have a look at the backflow valve on our water heater. My curiosity is getting the best of me.

sreigle · 01-27-2008, 02:31 AM

Michael, as Will said, there is a check valve at the city water inlet. If you remove the screen you'll see the white pin that's part of the valve.

If yours went through freezing weather it's very possible the o-ring in that valve was shut out of place, effectively eliminating the function of the valve. This happened to me and is why I recommend when winterizing to remove the screen and press that pin. There is water trapped behind there. Pushing the pin relieves the pressure. Otherwise when it freezes the ice expands and pushes the o-ring out of place.

Mine with the displaced o-ring was back when we had a stick home. I was able to work the o-ring back into place by carefully working it with a small screwdriver. Be very careful not to damage the o-ring.

berridge · 02-21-2008, 03:56 PM

Finally I have found time to replace the hot water check valve. I had to purchase a 1in deep (long) socket and a 24in bar to get it loose! It is in the hot water line threaded into the top rear of the tank. I believe this is because the valve is part of the hot water tank bypass system so if it is not functioning properly it is possible that antifreeze would leak into the tank during the winterizing process.

bsmeaton · 02-21-2008, 06:21 PM

Slick is right - it has to be there on the hot outlet to prevent antifreeze feeding back into the tank when in the tank bypass mode. The tank bypass is only one 3-way valve that sends water to the hot out hose instead of the cold in hose. The check valve serves as the closed valve on the other side of the tank to make it bypass.

Ozz · 02-22-2008, 12:27 AM

This may Help

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