Autumn, and a Young Man's Fancy Turns to -- Heating His Boat

[Dockhead]

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 and generator 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 stairs
* 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 time.

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.

[Dockhead]

In fact, it is possible to put in "dual fuel conversion" elements, in hydronic radiators. A couple of these to the tune of maybe 1400 watts, and turn on the circulation pump, and Bob's your mother's uncle, I think.

[Kokanee]

Originally Posted by Dockhead

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 stairs
* A radiator in the aft heads compartment
* A radiator in the aft main cabin

with header tank and circulation pump.

Those multi-plate heat exchangers are super-efficient, easy to maintain, and you can add/subtract plates to alter the efficiency.

I used one at work where the heat from a Caterpillar 3516 1000KVA generator was used to heat a 5000 m2 greenhouse. I highly recommend them.

[Artif]

Dont over think it
Dump the Ebe&^%$ and fit a domestic oil fired combi boiler (with a small tweak) they run on diesel Senator Combi » Turkington Engineering
Use a domestic central heating water pump and your done, plug in to your calorifier as well, if you really want, minimal draw on your electrics. proper heat output (providing you have decent radiators) and unlimited hot water.
We had conventional boiler from them, on our boat, 62ft danish trawler, heated the whole boat and 100l calorifier in about 15 minutes even when the Hamble froze over.
No problems ever, never even serviced in 5 years of continuous use.
Going to fit the above combi on our new (to us) boat. Cant wait to throw out the useless webasto.

[Dockhead]

OK, so the more I think about this, the more I like the idea. The cost of even just the parts would probably more than pay for the fuel to run the Eber that much more, but I have decided that it will just be a fun project. Taking waste heat from the generator will amount basically to co-generation -- heat up the boat and make hot water while the generator is running, without drawing power.

Now the economics of this project don't justify hiring a real HVAC engineer, so I'm going to need to basically wing the engineering part.

What I'm going to do, I think, is this:

1. Heat distributed by two radiators, one in the after heads, one in the aft master cabin, one bus heater under the companionway. That's enough to put out maybe 4 or 5 kW of heat -- not too shabby.

2. Header tank at the highest point -- top of the heads radiator. I won't be shy about putting it in plain view after seeing the same in the personal yacht of the owner of KM Yachts a couple of months ago.

3. Distribution loop plumbed in series through generator and main engine heat exchangers. A side effect is that the generator can be heated by the main engine and vice versa if required just be switching on the relevant circulation pump.

4. I don't really know how to tap into the generator cooling system. I'm thinking to just take it out upstream of the heat exchanger and dumping it back downstream, and counting on the circ pump to move the coolant.

5. The radiators and bus heater will be connected in parallel, via three-way manifolds bought from a heating supply company.

6. The system will need three circ pumps.

7. I will put in the biggest "dual fuel" electrical elements I can find into the two radiators. 800w each for 1.6kW. Turn these on and turn on the circ pump and voila -- electric hydronic heat. Might reduce my dependence on fan heaters when I'm on shore power.

8. I don't really know how to size the heat exchangers. The 44kW Wiltec ones look ok.


Comments, especially from people with a better understanding of the engineering, most welcome!

7. I'm designing a cool control panel for it, with four temperature readouts, including calorifier temperature.

[zeehag]

just sail south

[Dockhead]

Originally Posted by zeehag

just sail south

Ya, I don't want to!

I hate hot weather.

I love Northern latitudes, and plan to go even further North in the future.

I don't mind cold weather at all; just nice to get the boat cozy and dry!

[zeehag]

conundrum. good luck. i had excellent good luckin coldass winters in sd with oil lamps but daytime was warm enough, only needed in evenings. friend used a dickenson heater for heat and heated his teapot on it.
another friend had a formosa 51 with a wood stove he could also cook on..

[hpeer]

Sounds like you have your plan, which I don't quite follow. No matter.

I think if it were me I'd put in a couple of Espar D-4 heaters. Hot air. They are small and do the trick. Having 2 you have zone heating and redundancy. I find no need for lots of fancy ducting.

I agree with your desire for warm dry air.

[Dockhead]

Originally Posted by hpeer

Sounds like you have your plan, which I don't quite follow. No matter.

I think if it were me I'd put in a couple of Espar D-4 heaters. Hot air. They are small and do the trick. Having 2 you have zone heating and redundancy. I find no need for lots of fancy ducting.

I agree with your desire for warm dry air.

Thanks.

My plan is a bit of a lark -- because I already have hydronic central heat.

I just hate dumping into the ocean all the waste heat put out by main engine and generator, when I'm always in need of heat inside. This plan is purely intended to capture that heat and use it to heat up the boat and make domestic hot water.

It would be pure madness except that I heat year round.

It would make much more sense in a motor boat where you're using the main engine all the time.

[ColdEH]

Explain to me your " calorifier" are you running a hot coolant heated element through your hot tank ?

And your maintenance schedule on your eber is crazy , we have a 2010 webasto 35000 btu , use it year around for hot water and heating with no issues , just replace the nozzle every two years and you are good to go .

Regards


Sent from my iPhone using Cruisers Sailing Forum

[ColdEH]

Sorry correction . The webasto DBW 2010 is a 45000 btu unit .

Regards


Sent from my iPhone using Cruisers Sailing Forum

[Dockhead]

Originally Posted by typhoon

Explain to me your " calorifier" are you running a hot coolant heated element through your hot tank ?

And your maintenance schedule on your eber is crazy , we have a 2010 webasto 35000 btu , use it year around for hot water and heating with no issues , just replace the nozzle every two years and you are good to go .

Yes, my calorifier has actually two loops in it -- one for main engine coolant, the second one for central heating hydronic circulation.

[Colin A]

Don't have one myself but a few of the workboat projects I have worked on had these.

Marine Heaters

Seemed to work well on less then 60' pilothouse workboats.

[Dockhead]

Originally Posted by typhoon

Explain to me your " calorifier" are you running a hot coolant heated element through your hot tank ?

And your maintenance schedule on your eber is crazy , we have a 2010 webasto 35000 btu , use it year around for hot water and heating with no issues , just replace the nozzle every two years and you are good to go .

Yes, my calorifier has actually two loops in it -- one for main engine coolant, the second one for central heating hydronic circulation.