In article ,
"Doug Dotson" wrote:

I've always been of the impression that heat exchanger type
water heaters don;t work well with raw water cooled engines.
The raw water doesn't get all that hot in its short trip through the
engine.

Doug
s/v Callista

Depends on the setup, i would suppose. Most of the commercial
units I have used have a two loop design with a heat exchanger
between the loops, and the raw water running thru the secondary
loop. They have a thermostat in the Primary loop, that sets
the temp for that loop and the engine. Typically these are 180F
and can be as high as 200F. The secondary loop only has to remove
the total energy being dumped by the primary loop and can run at any
temp that allows removal of the heat energy being produced. In my
cabin heating system design, the primary loop is designed to:
1. heat the airspace in the cabin.
2. heat the domestic hot water.
3. when all the other energy needs are met, dump the waste heat
to the outside air.

The primary loop runs at 180F which is thermostat regulated.


Bruce in alaska
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add a 2 before @