Community Forums

Gpanek · 03-16-2019, 10:53 AM

After 5 months idle we did our first 2019 camping trip in our Winnebago Sunova Itasca 26P class A. Upon using the shower I found water going from hot to cold to hot to cold continuously. It sounded like the pump for the hot water heater was pulsing. Didn't do this last year. In looking under the sink, and reading up a bit, I see there is only one water pump. A Shureflo that pumps from the fresh water tank. At any rate, when the hot water is turned on at the sink it seems to go steady but I still hear a noise coming from the hot water tank, seperate from the sound of the water pump. I used to think it was a seperate pump. Anybody know what that buzzing sound could be when the hot water is turned on? Or what the hot cold alternating in the shower could be? thanks for your help.

Alan24601 · 03-16-2019, 10:57 AM

Open the pressure relief valve on the water heater and release the entrained air. Should solve your problem.

MSHappyCampers · 03-16-2019, 11:07 AM

Hi ! Welcome to IRV2! We're sure glad you joined the gang!

Noticed you are kinda new on IRV2 and wanted to say hello. Hopefully Alan's advice will help! Have fun and keep her between the ditches!

Good luck, happy trails, and God bless!

Old-Biscuit · 03-16-2019, 11:08 AM

NO ....leave the T&P Relief valve alone.
Suppose to have an 'Air Pocket' in top of water heater.
Water swells when heated and w/o the air pocket the pressure will increase enough to cause T&P Relief to 'weep' (air can be compressed....water will not)
IF you loose the air pocket you should re-establish it
*Turn water off
*Open nearest faucet to relieve pressure hotside...leave open

*Open T&P until water stops flowing
*Let T&P SNAP Close
*Turn water back on
*Close faucet

The humming/buzzing noise is due to the check valve in WH Tank HOT out getting clogged with debris/scale ....
Usually when that starts happening it leads to complete failure of hot water flow as check valve fails

Check Valve is internal to the 'nipple' on Hot out where hot line fitting screws onto.
Replace the check valve
Drain and flush water heater to remove the crud....should be done at end of each camping season

John Wayne · 03-16-2019, 12:55 PM

Do you have an outside shower make sure both hot and cold faucets are turned off.

Mojim · 03-16-2019, 02:29 PM

Quote:

Originally Posted by Alan24601

Open the pressure relief valve on the water heater and release the entrained air. Should solve your problem.

yep!

Old-Biscuit · 03-16-2019, 02:53 PM

Quote:

Originally Posted by Mojim

yep!

Nope....

If you open T&P with water supply ON you will displace the air pocket...end up with T&P leaking when water is heated

If you open T&P with water supply OFF then you will ADD air creating the air pocket which is good.

Opening T&P will not resolve check valve chattering/humming/buzzing when using hot water

Alan24601 · 03-16-2019, 11:59 PM

Worked for me.

Mark99 · 03-17-2019, 11:40 AM

I have a 2014 Winnebago Sightseer and have had to replace check valves twice already. Not due to noise but once stuck open which caused problems trying to winterize. The second time one stuck closed so causing no water flow. I can see where you might get a noise or irregular flow thru the check valves. In my case I don’t know if it is the design or caused by bad water.

festrvl · 03-18-2019, 04:52 PM

I'm not sure why this check valve is necessary. I've just had to re-do my hot water tank bypass and did away with it altogether, adding a shut-off valve instead.

Gpanek · 03-18-2019, 05:18 PM

Well I did drain and flush the HW tank. Lots of white calcium came out. I failed to do this last year, since the year before didn't yield that much crud. Will do now every year for sure.

The check valve is in a god-awful place to get at. I removed some plumbing to get at it but could not crack it loose, especially since the terrible position i was in didn't allow me any leverage on it. I guess I will just live with the buzzing. I also noticed in older posts that people mentioned something about a noise arising from the check valve if the line out is at an immediate right angle, which mine is. Any insight into that?

I will keep an air pocket at the top of the HW tank. thanks for explaining how that works and the importance.

Ok, tried the shower, both inside and out. Still oscillates from hot to cold. pump runs for 5 seconds with hot water coming out, then stops for a couple seconds with cold water coming out, then pump comes on again for 5 seconds with hot water. No apparent leaks anywhere. The pump doesnt turn on arbitrarily when no outlet is open, so doesnt appear to be any leaks. hot water seems to only come out of shower when pump is running. I wonder if I just need a new pump.

Old-Biscuit · 03-18-2019, 11:54 PM

Quote:

Originally Posted by festrvl

I'm not sure why this check valve is necessary. I've just had to re-do my hot water tank bypass and did away with it altogether, adding a shut-off valve instead.

Because RV MFG was too cheap to plumb/install the shutoff valve on Hot out

Easier to install check valves on WH Tank PRIOR to installing them

Check valve is used to stop backflow thru hot out when WH Tank is bypassed
With shutoff in hot out.....no check valve needed

Old-Biscuit · 03-18-2019, 11:59 PM

Quote:

Originally Posted by Gpanek

Well I did drain and flush the HW tank. Lots of white calcium came out. I failed to do this last year, since the year before didn't yield that much crud. Will do now every year for sure.

The check valve is in a god-awful place to get at. I removed some plumbing to get at it but could not crack it loose, especially since the terrible position i was in didn't allow me any leverage on it. I guess I will just live with the buzzing. I also noticed in older posts that people mentioned something about a noise arising from the check valve if the line out is at an immediate right angle, which mine is. Any insight into that?

I will keep an air pocket at the top of the HW tank. thanks for explaining how that works and the importance.

Ok, tried the shower, both inside and out. Still oscillates from hot to cold. pump runs for 5 seconds with hot water coming out, then stops for a couple seconds with cold water coming out, then pump comes on again for 5 seconds with hot water. No apparent leaks anywhere. The pump doesnt turn on arbitrarily when no outlet is open, so doesnt appear to be any leaks. hot water seems to only come out of shower when pump is running. I wonder if I just need a new pump.

Pump is short cycling due to low flow demand
Pump comes on and discharge pressure PUSHES water thru WH TANK. But flow is low so pressure goes high enough to open pump pressure switch ---pump stops and hot flow stops but cold still has enough pressure and lower resistance so it continues to flow which causes presure to go low enough to close pump pressure switch and cycle repeats

Clogged up check valve in WH Tank Hot out cause the low flow in hot water line...which cold water line doesn't have

Check valve.....
Good luck!

Gpanek · 03-20-2019, 07:20 AM

That makes sense and also by changing it I would most likely stop the buzzing noise. the check valve is the culprit. Gotta figure out a way to get at it, to change out. thanks.