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 Heat and Hot Water
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1st Mate

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Initially Posted - 07/02/2022 :  09:20:39  Show Profile  Reply with Quote
Not a project for the faint at heart. After oscillating back and forth for a year of so, I finally bit the bullet and installed an ESPAR hydronic diesel heating system. Since the boat is now in Boston, it can get really cold on the water, even in late summer, and I really hate being cold. There are a number of cheaper choices for heat and hot water, but, in terms of reliability and safety, I found the ESPAR diesel heater to be the best choice for me. (your milage may vary)

If you are not familiar with ESPAR, it is German company that builds super reliable diesel boilers for preheating diesel truck engines in cold environs. They are usually mounted outside the cab, and can take the salt, dirt, and abuse of the highways. The kit consists of the boiler, a pump to circulate a glycol mixture, a fuel pump, controller, and wiring harness.

I also purchased an 5KBTU air handler for hot air heat in the cabin and a heat exchanger for domestic hot water. I also purchased the 'Marine' kit , which consist of ABYC approved diesel fuel lines, exhaust hose with built in muffler, and exhaust thru-hull. I purchased my kit off of Amazon. The air handler, heat exchanger, 'Marine' kit all came from an outfit in the UK.

I installed the boiler, diesel day tank, glycol header tank, pumps and electronics in the cockpit dumpster. All combustion takes place outside of the cabin in the dumpster. I measured the run time temperature of the boiler at 100 deg (you can touch it), and the highest temperature on the exhaust port at 140 deg. The actual exhaust hose is double walled and remains at ambient temperature.

The glycol loop, enters the cabin, goes thru the heat exchanger for hot water under the galley

and then to the air handler located in the storage area under the port settee, for hot air

where the hot air exits thru a grill into the cabin at floor level

The exhaust from the boiler exits the back of the boat at the stern thru a special thru-hull

The diesel day tank holds 2+ quarts and should last the season. To control the boiler, it is one button push to fire up, which will run the boiler to maintain 165 deg in the glycol loop for 30 mins. You can extend or stop at anytime. It takes about a minute to fire up and another minute to bring the glycol loop up to temperature. The glycol pump requires around 5A and the air handler, 2A. In general, no smoke, no diesel smells, even in the closed dumpster.

Hot air heat is controlled by a separate controller, which can be set to manual or automatic, and varies the blower motor speed based on heat demand.

A few notes about installation: keep the glycol loop simple, the pump is not that strong, and any air trapped will prevent circulation. The ability to bleed the loop easily is important. In addition, have a CO detector in the cabin. (You should have one anyways, if you have any combustion taking place on the boat, including your outboard). Also, as all the instructions are in German, I found a number of Youtube videos of ESPAR installations for Van conversions, which helped a lot.

"Frayed Knot" 1989 C-25 WK/SR #5878

Edited by - bjoye on 07/02/2022 09:24:54


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Response Posted - 07/04/2022 :  11:42:17  Show Profile  Reply with Quote
Pretty impressive and well executed project. This should go in the magazine.

Tim Keating
1985 C-25 TR/FK #4940
Lake Don Pedro, CA
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