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Water Heater Check Valve

CT_WANDERER
Explorer
Explorer
My hot water stopped flowing. CV went bad, I removed the internal parts. Have hot water now. I have not had the chance to give it a full workout, yet. I know the check valve comes into play when winterizing the MH. Does it have any other purpose? Do I need to replace it? I spend the winter in the RGV and summers back in New England. Thanks Gary
14 REPLIES 14

12thgenusa
Explorer
Explorer
ktmrfs wrote:
12thgenusa wrote:
It's only purpose is so you can have a one manual valve bypass system instead of a two manual valve system for winterization.


yup, And do you notice that when you turn down the water flow rate the temperature changes? like in the shower? If so, it's that darn check valve. very nonlinear flow rate.

Toss it and put on a two valve WH bypass or winterizing and you'll be lots happier.

Not really. I don't vary the flow rate once I have the shower temp set except to close the shutoff valve while soaping up. However . . .
My old 5er had a two valve bypass and no check valve. The shower would give you a blast of hot water after the shutoff valve was opened. The current trailer has a check valve and one bypass valve and you get a blast of cold water. Take your pick. Cold is probably safer.

I saw a mod some time back where check valves were installed in the hot a cold supply lines just upstream of the shower and that fixed the problem.


2007 Tundra DC 4X4 5.7, Alcan custom rear springs, 2009 Cougar 245RKS, 370 watts ET solar, Victron BMV-712, Victron SmartSolar 100/30, 200AH LiP04 bank, ProWatt 2000.

ktmrfs
Explorer II
Explorer II
12thgenusa wrote:
It's only purpose is so you can have a one manual valve bypass system instead of a two manual valve system for winterization.


yup, And do you notice that when you turn down the water flow rate the temperature changes? like in the shower? If so, it's that darn check valve. very nonlinear flow rate.

Toss it and put on a two valve WH bypass or winterizing and you'll be lots happier.
2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!

Okie1
Explorer
Explorer
I replaced mine with a quality brass valve from Home Depot.
2016 F-350 four door Lariat 4X4 long bed & 2012 Sabre 34RLQS...

Ex-Tech
Explorer
Explorer
Old-Biscuit wrote:
Check valve serves one purpose..replace the cost/installation of another shutoff valve.

Check valves are installed by RV MFG....not by water heater mfg.

Check valve in WH hot out is to prevent backflow into WH when WH is bypassed.
Check valve i WH cold is to prevent Hot backflow into cold system....which really is minimal w/o that check valve and only when system is stagnant (no flow). As soon as there is flow (hot or cold)---end of ANY hot into cold.

If you 'winterize' using anti-freeze then it will get into WH
So replace check valve (better quality---brass vs that cheap plastic junk)
OR be done with it and install a shutoff valve on hot out so it can be closed when WH is bypassed.


This correct.
It is NOT a safety device nor does it keep cold water from entering the hot side of the water heater.

Roger10378
Explorer II
Explorer II
I always winterize by blowing out the lines with air so when my check valve failed I just removed the internals. It's been that way for several years now.
2005 Cardinal 30TS
2007 Chevy 2500HD D/A

CT_WANDERER
Explorer
Explorer
That is what I thought, that the CV was more of a function for Winterizing. The CV is in the Water Heater outlet and I have a hand valve for the by-pass on the inlet. For now, I am leaving out the internal parts. The O-Ring was broke that goes on the poppet and the retainer that hold the spring onto the poppet is missing. I will pick up a spare CV or a shut-off valve, just in case I have to put antifreeze in the water system. But as long as I keep out the north during winter I should be OK for now. Thanks everyone for your input. Gary

RJsfishin
Explorer
Explorer
Mine has no check valves, never had any, and I have never had any hot to cold water problems. And for all the grief those check valves have caused RV'ers, it would be a bad idea to ever replace one,.....IMO.\
And if you think RV MFGs do everything correctly, well, that is just bad thinking,....also IMO
Rich

'01 31' Rexall Vision, Generac 5.5k, 1000 watt Honda, PD 9245 conv, 300 watts Solar, 150 watt inv, 2 Cos 6v batts, ammeters, led voltmeters all over the place, KD/sat, 2 Oly Cat heaters w/ ox, and towing a 2012 Liberty, Lowe bass boat, or a Kawi Mule.

dougrainer
Nomad
Nomad
WNYBob wrote:
CV's are safety devices, so your WH does not blow up!


Sorry, This is not true. You may be thinking of the POP OFF valve. Doug

Old-Biscuit
Explorer III
Explorer III
Check valve serves one purpose..replace the cost/installation of another shutoff valve.

Check valves are installed by RV MFG....not by water heater mfg.

Check valve in WH hot out is to prevent backflow into WH when WH is bypassed.
Check valve i WH cold is to prevent Hot backflow into cold system....which really is minimal w/o that check valve and only when system is stagnant (no flow). As soon as there is flow (hot or cold)---end of ANY hot into cold.

If you 'winterize' using anti-freeze then it will get into WH
So replace check valve (better quality---brass vs that cheap plastic junk)
OR be done with it and install a shutoff valve on hot out so it can be closed when WH is bypassed.
Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31

12thgenusa
Explorer
Explorer
It's only purpose is so you can have a one manual valve bypass system instead of a two manual valve system for winterization.


2007 Tundra DC 4X4 5.7, Alcan custom rear springs, 2009 Cougar 245RKS, 370 watts ET solar, Victron BMV-712, Victron SmartSolar 100/30, 200AH LiP04 bank, ProWatt 2000.

schlep1967
Nomad
Nomad
It is only about a $10 part. If you got the old one out you already know how to put the new one in. It took me about 10 minutes.
2021 Chevy Silverado LTZ 3500 Diesel
2022 Montana Legacy 3931FB
Pull-Rite Super Glide 4500

ksg5000
Explorer
Explorer
Replacing water heater CV has been on my to-do list for two seasons - it's a minor annoyance which results in my cold water being hot for a few moments.
Kevin

enblethen
Nomad
Nomad
Check valve on cold water prevents hot water from feeding into the cold.
It is not a safety valve. The pressure/temperature relief valve is the safety device.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

WNYBob
Explorer
Explorer
CV's are safety devices, so your WH does not blow up!