I've been thinking about this for a few years and have not yet come to any conclusion or taken any steps.
I already have an Eberspacher 10kW hydronic furnace which makes domestic hot water
plus runs three fan coils with outlets in all the interior
spaces of the boat.
This does heat the boat, although when it's really cold, like around freezing, it will not get the whole boat up to 20C. Also it's noisy, uses electrical
power, and every hour of operation brings it an hour closer to the next expensive servicing. This I do every two years, and the last one required replacement of the burner tube at horrendous expense.
So one reason why I haven't changed anything is because any improvement has to be measured against just running the existing system for an extra hour or whatever.
I've considered installing heat exchangers to get engine
waste heat into the hydronic system. And keep rejecting these plans because of expense and complexity vs just running the Eber.
But it continues to torture me that I'm dumping megawatts of waste heat into the ocean when I need heat all year round, and burn precious diesel fuel
to make it
So I want to try to figure this out now once and for all, settling on something simple enough to be practical in light of the alternative.
I think I may have come up with something.
What if I put in one plate type heat exchanger
, something like this:
WilTec - Stainless Steel Heat Exchanger 20 Plates Plate Heat Exchanger 44 kW 50672
into the main engine's calorifier
loop. I would splice this in downstream of the calorifier
to let the calorifier get "first dibs" on the hot coolant
. I would add a circulation pump (which I have already bought and need anyway because the circulation is poor).
Then, I would create a new loop which would run three devices:
* A bus heater in the salon
under the companionway
* A radiator in the aft heads compartment
* A radiator in the aft main cabin
with header tank and circulation pump.
I am trying to keep it simple and therefore am NOT now thinking about putting a heat exchanger
into the main hydronic loop.
This simple new loop would not be very costly or difficult to install. The existing hydronic system does heat the aft heads but not very well.
Very often, I've noticed, when sailing in cold and especially in cold and wet weather
, I am really wishing at the end of the day to have warmed up the boat, made a tank of piping hot water
, and dried out the heads. I will be running the engine
anyway for the last hour or so in order to charge up the batteries and/or get through harbor pilotage.
I could make this slightly more complex by adding a second heat exchanger spliced into the generator's cooling
system, but this would be nice. At anchor
, I often find myself making hot water with the immersion heater while doing a generator
run, which is really pretty stupid if you think about how much waste heat is going into the ocean while you're doing that generator run. Like this, I could not only make hot water but also warm up the heads, so perfect shower
Those of you in tropical waters won't understand any of this! But up here, cruising year round in latitudes from 50N to above 60N, heat is life! Needed year round!
Anyone see a problem with this plan, or have any suggestions on improving it?
I thought about including an electrical
immersion heater in this, something going up to say 3kW and adjustable power, and maybe even connected to a separate shore power
inlet. I heat with electricity probably 75% of the time, using fan heaters. But I couldn't find a device like that, and the fan heaters are not actually such a big problem, so I dropped it in the name of avoiding unnecessary complexity.