Header tank for hot water heater

[steve77]

Our boat's hot water heater is located such that it is higher than the radiator filler cap and expansion tank of our Yanmar auxiliary. I want to hook up the engine heater ports of the hot water heater to the engine cooling system.

I've read that I will need to add a header tank with radiator cap at, or slightly above, the elevation of the hot water heater in order to avoid air bubbles and also to allow me to add coolant as needed. This all makes sense to me.

The photo below seems like an easy way to accomplish this. I don't see the need for a header tank, just a filler cap. This unit comes with a nipple to attach the small hose to the expansion tank.

So my plan is to cap off the existing hose for the expansion tank and relocate it up near ether hot water heater. I will then buy one of these remote filler caps (if not this exact one, then something like it). The filler cap and the expansion tank will both be mounted near the hot water heater.

Any thoughts?

[ggray]

Are you saying that this water heater is heated with electricity now, and you want to use the engine to heat it now?

I toyed with the header tank thing for my situation. Originally I had two water heaters on our catamaran, one in each stern. For various reasons, I replaced them with a single WH that had two heat exchangers, mounted in one stern. The heater hoses from the opposite engine are routed nearly 3 feet above the engines. Supposedly air in these lines can cause problems, and a header tank is required to help deal with it. I finally decided not to install one unless I found it was necessary. I am very careful to make sure the lines are void of air whenever I work on the system.

Not sure if this will help you though.

[steve77]

Thanks, ggray. Yes, right now we are only heating using electricity and I want to use the engine coolant to do this.

I thought this filler cap idea was a good one. I don't see the need to have an actual header tank at the high point of the cooling system, just the filler cap and an expansion tank. The filler cap connects directly to the 3/4" heater hoses using barbed connectors.

If anyone sees a flaw in my reasoning, sing out.

Steve