Hot water heater

[rickasbury]

Ok, back in the water. Someone else suggested with the boat running and the pump switch off, if the water comes out than the heater core is bad...but that would say that it is hot water coming off the heat exchanger circulating in the heater and not coolant. These heaters are not cheap! Would you all concur?

 

[kd4pbs]

Turn off the pump, then open a hot tap. Let all the pressure bleed off, then close the tap. Start the engine and run around a while, heating all the water in the tank - probably 20-30 minutes or so. With engine running, open a hot tap. I would imagine a small amount of water will come out due to the expansion of the water. If lots come out and continues to flow, then you've got a bad water heater with a hole in the heat exchanger portion.
Yeah, those water heaters are not cheap for sure.
Another way to find out would be to bypass the coolant loop in/out, pressurize the fresh water side, and see if water flows out of the open coolant loop of the water heater.

 

[muc]

It's been over a decade since I winterized a water heater. But it looks like the check valve is screwed into the hot outlet, should be in the cold inlet. Take a close look below where those hoses go into the heater. Should be a C and H stamped below them. If someone got things mixed up you can get hot water at a cold faucet, but only for short time, it will turn cold in a minute.