Water Heater Check Valve

[egarant]

Hi,

I am about to replace my Suburban SW6D water heater and I noticed the hot water outlet had a check valve installed but the cold water inlet did not. Should there be a check valve on both inlet and outlet?

Eric

[egarant]

I took that check valve out (non at all now), muscled and swore that new unit in it's place.....god I hate RV plumbing.....

Fired up, no gas or water leaks. Will check for water/gas leaks after arriving at first destination.

[ktmrfs]

downside of the single check valve vs. no check valve and a two valve bypass is that with a single check valve, usually the cheapest available, the valve is usually not a constant restriction and when you are in the shower and turn down the volume, you may get a blast of cold water. Our trailer did that and when I pulled it out and put in the two valve bypass problem went away.

[DrewE]

Dusty R wrote:
That check valve could be to prevent thermo syphon, which will cause your cold water to be warm and the water heater to cycle often.

The only way you could get thermosiphon is if there were a loop for the water to go around--that is, if the hot and cold water pipes were connected somewhere besides the water heater. That would only come up if, say, the water heater bypass is incorrectly set or a shower is turned off at the shower head but the valves are both on, and would necessarily lead to unwanted variations in water temperature (mostly hot water temperature) due to mixing hot and cold water when it's being drawn.

Without a check valve, there can be a little bit of hot water that flows into the cold pipe when you first use water due to the added pressurization of the system when the water in the heater gets hot. It's not generally enough volume to get as far as a faucet, nor does the water continue to flow the wrong way and cause the heater to cycle excessively. (The added pressure, as I understand it, comes mainly from the air pocket in the water heater getting warmer while maintaining a practically constant volume, probably coupled with a marginally higher water vapor pressure. Liquid water itself has a negligibly small coefficient of thermal expansion.)

[Old-Biscuit]

OP has a 2013 Year Model

Have NO check valves on my WH and never experienced any thermo syphon.....what ever that is

Never experienced cold inlet to WH Tank getting warm enough to migrate farther down cold water line

Check valves are not needed.

[Dusty_R]

That check valve could be to prevent thermo syphon, which will cause your cold water to be warm and the water heater to cycle often.

[dougrainer]

1. Depending on the Year model of the RV and IF it was built in California, Water Heaters had a check valve on the Intake and exhaust per California plumbing code. This requirement was removed in the mid 2000's. The problem having 2 check valves was NOISE and the diminished volume of Hot Water flow. 2 check valves caused a whining noise.
2. Having a BRASS check valve on the Intake keeps the Hot water from heating up the feed water line and possibly causing warm water at a cold side of a faucet.
3. If you have a check valve on the Hot exhaust of a water heater, that is usually because the OEM has used a hybrid BYPASS winterization system that uses one valve to bypass for winterization. When this check valve is installed, it keeps water from entering the Water Heater thru the hot exhaust side when the winterization handle is in winterization mode. If you have this type system and you still get water(antifreeze) into the WH when winterizing, it is because the check valve was NOT installed or is defective. Doug

[Old-Biscuit]

egarant wrote:

Old-Biscuit wrote:
RV MFGs install those check valves cause they are cheap and easy to do prior to installation of WH
Cheaper then a shutoff valve/piping/connections for valve and the labor

Winnebago and another MFG go even farther by installing check valves in Cold Inlet

I have 3 valves (cold in/Hot out/Bypass) and NO Cheap junk check valves


Yes you can do away with the check valve
Might I suggest installing a Sharkbite, Gatorbite, FlairIt shutoff valve on Hot out so If needed WH Tank can be isolated and bypassed




Just curious:
Why the replacement of that Suburban WH?

The water heater was 8 years old and even after having it serviced I was getting a lot of propane fumes inside the rig, something I never experienced when the RV was new.

After removing it I noticed the tank was a little rusted on the outside bottom so I decided just to replace the unit.
Where I live and travel the water is extremely hard and even though I replace the anode yearly I am sure it takes a toll.

They are not terribly expensive online so I thought a new one was the prudent way to go.

Once a Suburban Steel tank starts rusting out...time to consider replacement
*Suburban does NOT have replacement tanks like the Atwood Aluminum

[egarant]

Old-Biscuit wrote:
RV MFGs install those check valves cause they are cheap and easy to do prior to installation of WH
Cheaper then a shutoff valve/piping/connections for valve and the labor

Winnebago and another MFG go even farther by installing check valves in Cold Inlet

I have 3 valves (cold in/Hot out/Bypass) and NO Cheap junk check valves


Yes you can do away with the check valve
Might I suggest installing a Sharkbite, Gatorbite, FlairIt shutoff valve on Hot out so If needed WH Tank can be isolated and bypassed




Just curious:
Why the replacement of that Suburban WH?

The water heater was 8 years old and even after having it serviced I was getting a lot of propane fumes inside the rig, something I never experienced when the RV was new.

After removing it I noticed the tank was a little rusted on the outside bottom so I decided just to replace the unit.
Where I live and travel the water is extremely hard and even though I replace the anode yearly I am sure it takes a toll.

They are not terribly expensive online so I thought a new one was the prudent way to go.

[Old-Biscuit]

RV MFGs install those check valves cause they are cheap and easy to do prior to installation of WH
Cheaper then a shutoff valve/piping/connections for valve and the labor

Winnebago and another MFG go even farther by installing check valves in Cold Inlet

I have 3 valves (cold in/Hot out/Bypass) and NO Cheap junk check valves


Yes you can do away with the check valve
Might I suggest installing a Sharkbite, Gatorbite, FlairIt shutoff valve on Hot out so If needed WH Tank can be isolated and bypassed




Just curious:
Why the replacement of that Suburban WH?

[egarant]

After doing some research I see that the only purpose is for winterizing, so since I never winterize (lucky I know) I am going to remove it and put a normal pvc connector in its place.

[enblethen]

Cold water line on some have a check valve to prevent hot water from backking into the cold water line.

[DrewE]

Not generally. The check valve is there mainly as a part of the winterization bypass system (and whether it's needed for that or not depends on what exact valve arrangement you have for the bypass valves). Many water heaters, RV and otherwise, have no check valves at all.