Isotemp hot water backing into system

[NYSail]

Hello all,
So just finished installing a new Isotemp water heater. Real nice unit and love the installed mixing valve it comes with. However I am having hot water backing into the system from the tank……. When using cold water will have an initial bit of above warm water then it clears out. Never had this issue before with last unit or on any other units I’ve installed on other boats. Thought there would be some sort of check valve built in.
will dig up the manual but figured I would post….. any suggestions?

thanks!
Greg

 

[dlochner]

Did you put a check valve on the CW intake? When the tank gets hot from running the motor the water expands and backs through the CW system. If you did install a check valve, is it new and functional? Was it oriented correctly?

 

[NYSail]

Nope….. I didn’t add one. Thought it was part of the unit. Last water heater was a cheapy and had it built in…… so did the raritan I bought for last boat so just assumed this had it as part of the unit. Instructions also make no mention of needing the additional part. Guess I’ll call them on Monday and verify……

greg

 

[dlochner]

The check valve is pretty inexpensive. You can get them at hardware store. Pay attention
to the arrow.

 

[SycloneDriver]

I thought I needed to add a check valve to my system but what I really needed to do was turn off the transom shower. The shower valve was on and set to warm. The shower sprayer was off, this allowed the cold and hot water to mix and back flow into the rest of the system with the normal changes of system pressure.