We are replacing our Raritan
heater. Our fresh water
system is set up like this: From the tank, the water goes to the pump, then to a Jabsco
accumulater, then to a sediment filter. Attached to the "out" port of the sediment filter is a "T" fitting. One line from the T fitting goes to the cold water faucet, the other line goes to the water heater. There is a check valve installed in the line to the water heater, which I assume is to prevent heated water from backing up into the cold water line and/or sediment filter as the water heats up and expands.
I have two questions:
1 - the installation
instructions for the water heater call for the installation
of a vacuum relief valve in the cold water supply line (the line from the T to the water heater). The purpose of the vacuum relief valve is "to prevent back siphoning which could cause the tank to empty and element to burn out."
Question: is this vacuum relief valve really necessary? I am having a hard time imagining a scenario in which 6 gallons of water would "back siphon" out of the water heater which is installed lower than the water tanks
2 - Because of the check valve installed in the cold water supply line (the line between the T and the water heater), when water heats up in the water heater it expands and a little water vents out of the safety
relief valve. The instructions for the water heater calls for installation of a two gallon expansion tank in the cold water supply line which I suppose would take care of this issue, but we do not have the room to install one of these. I could probably find room to install a second small accumulator in the cold water supply line, but I don't know if those can tolerate hot water.
Any suggestions? Or should I just leave it the way it was? I can live with a little water venting into the bilge
, but it didn't seem quite right.
As always, any help is appreciated.