Hunter 40.5 Water heater to hydronic diesel

[baycloud]

Hey all, I'm away from the boat again so I had a question on trying to use the hydronic system to heat up the hot water tank. Is that possible with the stock hot water tank? Would there be existing fittings for a heat exchanger on the water heater if so?

I have read about diesel hydronic systems being used to heat up running water, but haven't been able to find more specifics or diagrams on how the heat exchange actually gets done - whether that is reliant on the water heater having a heat exchanger built-in

Merry Christmas!

 

[Tally Ho]

Hi @baycloud,

Merry Christmas!

i am a little confused by your question…

1)are you asking about heating water in the heater heater from the Diesel engine?

2) are you asking about hydronic heat for the boat?

These are 2 different systems.

Water can be heated from the engine (when running) if your water heater was set up that way. It has a coil in the tank, with inlet and outlet to carry hot coolant from the engine cooling system, through the coil, and it heats the water.
I have this set up on my boat, and it works very efficiently to give me some hot water when away from shore power. My engine is fresh water cooled, and I think this is a requirement for the waterheater setup (but I could be wrong).

The hydronic heating system uses a small boiler, and a pump to pump hot liquid through dedicated hoses to various heat appliances on the boat. I don’t know a whole lot about them, but Sail Life on YouTube did a whole upgrade to his boat using this sort of system. You can probably find it on YouTube.

Hopefully, others will chime in and correct me when I am wrong.

Greg

 

[Rick D]

Your water heater should have a heat exchanger for heating the water when the engine is warmed up and running and a heating coil to heat the water when the engine is off and you are on shore power (or generator). If I understood your question.

 

[dkinzer]

Our 41DS has a hydronic heater but it is only plumbed to the heat exchangers to heat the cabin. Comments on the survey indicated that the surveyor thought that it was also set up to heat water but I can find no connections that would facilitate that.

It seems to me that to set it up to allow the engine coolant to heat water and to allow the hydronic heater to heat the water the plumbing would have be to set up so that engine coolant and the hydronic fluid system were in series or, alternately, set up with valves to control which system would heat water. I suppose that another alternative would be to have a water heater with two separate heat exchangers inside.

I would like to have our hydronic heater able to heat the water, too so I plan to call the company that installed it and ask them how that is usually done.

 

[baycloud]

So basically, the 120VAC water heater either has the extra water heating coil hookup to utilize engine/hydronic heater heat or it doesn't. I'll have to trace it all when I get back to the boat

 

[baycloud]

One thing I did notice is that I have two expansion tanks - my theory is that one is connected after the engine, and one is after the hydronic heater. Good theory?

 

[dkinzer]

Here is an image of the Kuuma 11841 water heater that my 41DS has.

The two unlabeled nipples sticking out just below the horizontal centerline are the heat exchanger connections.