Hot Water Issue

AlwaysHomeNow · 03-27-2008, 07:33 AM

We've developed a whistle (or hum) whenever we turn on the hot water. Not sure if it's due to some kind of restriction, or what it could be. We do still have hot water, but it doesn't seem to be as hot as it was before.

Any suggestions on how to trouble shoot this?

Thanks.

keithandpenne · 03-27-2008, 08:11 AM

There is a check valve located on the discharge line (top) of the water heater that is prone to failure. When ours failed, it creates a hissing hum sound when running hot water. It does not effect the cold water.

Our first was replaced at the factory when in for other warranty work. The replacement failed 3 months ago and I picked up one at Bennett's RV in Granbury, Texas, for $11.++ and changed it out myself. Easy to do, just drain the tank enough to not have water run out when you remove the line and valve. Be sure to pick up some Teflon tape for the threads.

Good luck......

Motor31 · 03-27-2008, 09:07 AM

Good info there as mine is also humming. I couldn't isolate it that closely. I found the valve with the handle, how close to that is the check valve?

rverdlm · 03-27-2008, 09:11 AM

Keith is right! We had the same problem. You do need the check valve or the pressure in the cold water line becomes excessive when you turn on the water heater.

AlwaysHomeNow · 03-27-2008, 02:18 PM

Thanks everybody! I'll have the DH check it out when he gets home.

The people on this forum are just so great. I know we'd be forking out alot more money for minor fixes on this unit if it weren't for this forum.

Thanks again.

keithandpenne · 03-27-2008, 05:29 PM

Mike,

The check valve screws into the back of the water heater on the "hot water" out line. (top line)

Partially drain the hot water tank, (of course after turning off the heater) disconnect the line, unscrew the valve, pay attention to the direction of flow on the old valve as it will go in either way but you will not get any flow.

Its a 5 minute job once you get the basement access cleared.........

AlwaysHomeNow · 03-28-2008, 06:14 AM

I called the RV parts store around here and they didn't have any check valves in stock. But the tech said that you only need the check valve for winterizing the RV, to keep antifreeze from getting into the heater. He said that we could 'tap out' the valve part and it should work just fine for now. So that's what we did. No more whistle, and we've got the best supply of hot water we've ever had over the 3 years we've lived in our unit.

Thanks again for all your help.

bstark · 03-28-2008, 11:32 AM

Those ball valves typically restrict waterflow by their very design. You could, as an alternative to eliminating entirely, simply use a larger valve in concert with reducer fittings to allow more flow through a larger ball port within the valve. and still retain the ability to by-pass water heater when winterizing.

rdunk · 03-28-2008, 12:12 PM

Isn't the "check valve" being discussed actually a "backflow preventer" valve? These valves are required (probably mandated by health restrictions) to keep "trailer water" from flowing back into the public water lines. When mine went out, that is what the dealer tech person called it. They are made in brass or some type of plastic. The tech said the brass seem to last longer. When he replaced mine, he also left a spare, which I haven't needed yet.

I think there is another "backflow preventer" on the incoming water line in our MS.

I have noticed that some of the RV parks are installing a "backflow preventer" on their water faucets. Yes, these valves do reduce the incoming water pressure by the amount of water force that is required to open the valve to allow the fresh water to go through.

Our water filters also reduce our water pressure. The greater the filtration, the more the pressure is reduced.

FWIW

2 DA WDS · 03-28-2008, 12:49 PM

No the checkvalve on the water tank is just for winterizing. The 'backflow preventer' is actually in the Black Tank flush water line to prevent waste from getting back to the fresh water connection. And it is made of plastic and they do break.
A friend of mine had his hot water check valve fail and it reduced the hot water flow to a trickle. He replaces the valve and was back in business.

ponch · 03-28-2008, 01:18 PM

The bacckflow preventer valve is located behind the shower.
Axcess is gained by removing the panel, in our case, inside the
china cabinet. Ours is a CK.

Ponch

rdunk · 03-28-2008, 06:22 PM

Well, it sounds like our various MS's may be plumbed differently. A little more detail on the backflow preventer (s)on our RE3 --- we began to hear a noise each time we turned on the hot water. Our RV tech said it was the backflow preventer which is installed on the back of the hot water heater. He replaced it with a plastic one, and right off the bat it didn't stop the noise. The tech came back out with the a brass one, installed it, and that stopped the noise. The spare he gave me says on the label "back-flow preventer".

For sometime now, we have been having a similar noise when a cold water faucet is turned on in the 5er. It hasn't been a big deal, so I just haven't replaced it the preventer on the fresh water connection. However, now, when I run the water pump, some water comes out at the outside water connection. That makes it pretty obvious that the back-flow preventer on the inside of that connection has failed also.

So, that is two preventers I know of. If I have one behind he shower, then that would be three, I guess, and if I have one in the black tank flush line, that would make four. :lol: :lol:

sigo'suite · 03-28-2008, 07:06 PM

Robert, sounds to me like there is way too much prevent'n go'in on around your coach!! :shock: 8) :lol:

P/S: :arrow: Mr Admin man, please make the emoticons work again :!:

Motor31 · 03-29-2008, 10:14 AM

I think you are each talking the same thing, just differing on semantics. By it's design, a check valve IS a back flow preventer as it will only allow flow to go in one way.

The valve in behind the shower is also a vacuum breaker style back flow preventer. This just stops the siphon action from the black tank rather than having a physical flow preventer like the check valve.

In each case reverse flow has been prevented. In the water heater it has to stop water under pressure from flowing backwards. In the black tank flush case it prevents siphoning rather than pressurized flow. If your black tank is under pressure, lay off of the beans!

Motor31 · 03-30-2008, 11:18 AM

Yesterday I went hunting for the check valve at the rear of the water heater. The only thing I saw looked like a standard brass diameter reducing fitting a bit more than an inch long at the top. Nothing looking specifically like a valve assembly at all on the lines into or out of the heater other than the handle shut off valve on the bottom line.

Any other 38' owners have a possible location for it?

2 DA WDS · 03-30-2008, 12:24 PM

Quote:

Originally Posted by Motor31

I think you are each talking the same thing, just differing on semantics. By it's design, a check valve IS a back flow preventer as it will only allow flow to go in one way.

The valve in behind the shower is also a vacuum breaker style back flow preventer. This just stops the siphon action from the black tank rather than having a physical flow preventer like the check valve.

In each case reverse flow has been prevented. In the water heater it has to stop water under pressure from flowing backwards. In the black tank flush case it prevents siphoning rather than pressurized flow. If your black tank is under pressure, lay off of the beans!

Perfect explaination!

RE last post. If you dont have the single valve for winterizing there wont be a check valve. Just a thought:?: