Using Waste Heat

[Dockhead]

Originally Posted by s/v Jedi

I highly recommend you do not do this. Use a series-loop with additional heat exchangers for wngine and genset, or don't do it at all. Installing a heat-pump makes more sense; just put your mind so that while you realize it can be reversed to function as an air conditioner, you only use it for it's main function as heat pump.

I would love to have a heat pump! Would be ideal heat source when on shore power or with genset running. I might even be able to run it off my inverter. But this is massive expense

So why is the series-loop so essential, in your view? What do you see which is bad about this simplified solution, which seems pretty elegant to me?

[Dockhead]

Originally Posted by DeepFrz

Go to this page and click on the Olympia OL-60 link it will bring up a pdf file.
Sure Marine Service, Inc. | Marine Deluxe Heater Kits


Actually the Proheat X-45 shows the engine heat exchanger. The other pdf doesn't.

Thanks. Very interesting.

I wonder why the main engine heat exchanger is on the hot side of the heating system loop, and not on the return side. Hmmm.

Interesting the way they balance flow into the calorifier. Clever.

My system has the fan heaters working in parallel, rather than series, which seems better to me. Like that, the first heater will get most of the heat and the last one precious little.

This is a bit different from my case -- I have a calorifier with two loops, one fed directly from the engine. Here, the calorifier depends on central heat. Waste heat from the engine feeds the central heating system loop. I think it's wrong that they have the engine coolant heat exchanger on the hot side of the central heating system -- it means that if the furnace is running at the same time as the engine, the output of the furnace will not be reduced much if at all (only to the extent of any delta-T from hot output from the furnace and engine coolant T), and the furnace will be carrying the whole load, which is wrong.

I think you want the engine to carry as much of the heat load as it can, since that's free heat. So it should be in the return side of the central heating loop, so that it pre-heats coolant returned to the furnace. The furnace output will be modulated down, if the engine preheats the return flow enough. Not so?

[Jd1]

Originally Posted by Dockhead

What do y'all think?

<sigh> I give up ....
Way too complicated and prone to error.

[nwdiver]

In the PNW most boats have a bus (truck) heater hooked into their engine cooling system, it makes sense as when you are motoring in bad weather may as well have free heat in the boat, as you said it is most common under the companionway heating the salon, the draw for the fan is is not a draw as you are running the engine when using it. That coupled with propane demand hot water heater and a diesel bulkhead heater keeps me clean warm and cozy.

[s/v Jedi]

Originally Posted by Dockhead

I would love to have a heat pump! Would be ideal heat source when on shore power or with genset running. I might even be able to run it off my inverter. But this is massive expense

So why is the series-loop so essential, in your view? What do you see which is bad about this simplified solution, which seems pretty elegant to me?

The heat pump I have was $2,495.- for 18kBTU. It is made by CruisAir and also a 16kBTU A/C.

The series loop I keep nagging about is the one from that X-45 brochure. What I called "bypass" is called summer valves there and they have two circuits with interior heaters while I only have one. This is the way every professional install is done. You would add anither heat exchanger for the genset. Fool proof, reliable, proven.

[Dockhead]

Originally Posted by s/v Jedi

The heat pump I have was $2,495.- for 18kBTU. It is made by CruisAir and also a 16kBTU A/C.

The series loop I keep nagging about is the one from that X-45 brochure. What I called "bypass" is called summer valves there and they have two circuits with interior heaters while I only have one. This is the way every professional install is done. You would add anither heat exchanger for the genset. Fool proof, reliable, proven.

OK, well, thanks for the advice. I'll have a good think on it. It's a complicated decision.

Cheers.

[rebel heart]

Originally Posted by nimblemotors

This all sounds pretty complicated, and not what I'd want on a cruiser, something will break leak somewhere sometime..

How about instead you grow tomatoes in the engine room?

That's kind of what I'm thinking but maybe I'd feel different if I was in a really cold place. Considering the whole "boats spend 90% of their time not underway" I've had relatively good luck with the gravity fed diesel drip heater.

They have little water heater loops for those two I believe.

[Dockhead]

Originally Posted by rebel heart

That's kind of what I'm thinking but maybe I'd feel different if I was in a really cold place. Considering the whole "boats spend 90% of their time not underway" I've had relatively good luck with the gravity fed diesel drip heater.

They have little water heater loops for those two I believe.

Gravity fed drip heaters rule. That's the only kind of diesel heat you can rely on to work, and for you to be able to fix if something goes awry. The problem with fan-forced combustion furnaces like Webasto and Espar (Eberspaecher) is that they are computer controlled and complicated, and will be disabled automatically if something goes wrong, whereupon you must have a service tech with the plug-in computer, or no heat.

The only problem is a drip heater is not practical on boats above a certain size, because of the problem of distributing the heat.

So as someone mentioned, another advantage of having the ability to recover waste heat to use for space heating is that you have a backup in case the furnace goes down in a remote place.

Up here at more than 50 degrees latitude, as I mention, we need heat just about year round. We can get cold days even in July and August (didn't this year, however -- we had a lovely hot July). Some of the best sailing is in January and February when you might be chipping ice off the deck. So heat is kind of mission-critical.

[goboatingnow]

just "man up" i'd say, the advantage at these latitudes is that Jan and July can be interchangeable !!!. I mean if Michael Holland can sail to Antarctica , even after his eberspacher broke down , so can you sail around the south coast

http://www.amazon.com/Arctic-Antarct.../dp/1905172648

dave

[rebel heart]

Originally Posted by Dockhead

Gravity fed drip heaters rule. That's the only kind of diesel heat you can rely on to work, and for you to be able to fix if something goes awry. The problem with fan-forced combustion furnaces like Webasto and Espar (Eberspaecher) is that they are computer controlled and complicated, and will be disabled automatically if something goes wrong, whereupon you must have a service tech with the plug-in computer, or no heat.

The only problem is a drip heater is not practical on boats above a certain size, because of the problem of distributing the heat.

So as someone mentioned, another advantage of having the ability to recover waste heat to use for space heating is that you have a backup in case the furnace goes down in a remote place.

Up here at more than 50 degrees latitude, as I mention, we need heat just about year round. We can get cold days even in July and August (didn't this year, however -- we had a lovely hot July). Some of the best sailing is in January and February when you might be chipping ice off the deck. So heat is kind of mission-critical.

That's nuts, couldn't imagine sailing a boat in conditions like that. I'm in the tropics right now, in the Sea of Cortez where the water temperature is above 90f. Every day you're just doing everything you can to keep from melting.

I've noticed the heat distribution problem even on our 36', primarily up in the v berth where we sleep. I think it's made worse because of ambient breeze that tends to drift air from the bow to the stern. Even just a single dorade in the head makes a draft and the warm air is always moving to the stern.

I was going to get clever and try to install a drier hose behind a cabinet with a little PC fan in it, basically trying to suck warm air from near the heater into the v berth. For the $20 I might give it a shot.

[goboatingnow]

Up here at more than 50 degrees latitude, as I mention, we need heat just about year round. We can get cold days even in July and August (didn't this year, however -- we had a lovely hot July). Some of the best sailing is in January and February when you might be chipping ice off the deck. So heat is kind of mission-critical.

Actually hes sailing in the warm south coast, I grew up sailing in Scotland and the west of Ireland. Ive regulary seen June/Julys colder then November with daytimes below 9 degrees C! in summer . ( and no heating neither).

arrgh

dave

[Dockhead]

Originally Posted by rebel heart

That's nuts, couldn't imagine sailing a boat in conditions like that. I'm in the tropics right now, in the Sea of Cortez where the water temperature is above 90f. Every day you're just doing everything you can to keep from melting.

Yeah, it's funny, I grew up in a hot climate, and hated the cold when I first ventured north. Now, I hate hot weather, because there's nothing you can do about it if you've already shed all your clothes. If it's cold, you can always add more clothes. The invention of Gore Tex has also revolutionized comfort outdoors in cold weather.

Then I learned to ski and to snowmobile, and to understand that you can be outside all day in below freezing weather, and be perfectly comfortable.

So sailing is no different. It's lovely in the winter. Only thing I miss is lounging in the cockpit when not underway -- having a roomy, comfortable saloon becomes more important when you lose the cockpit as everyday living space.

[Dockhead]

Originally Posted by goboatingnow

Actually hes sailing in the warm south coast, I grew up sailing in Scotland and the west of Ireland. Ive regulary seen June/Julys colder then November with daytimes below 9 degrees C! in summer . ( and no heating neither).

arrgh

dave

"Warm" is a relative concept

But yes, I think my existing heating system is up to the demands of the South Coast. Anyway, there are Eberspaecher technicians available anywhere here. I am not designing my system for the English Channel, but for the more northerly climes I have my eyes on (we were supposed to go to Iceland this year).

[Antonkov]

I have been thinking about the very same subject and glad to see it on the forum.

This is my first iteration on the heating system design. At this point, I don't worry about the numbers and models as long as the "big picture" makes sense.

This is for a 46ft power cat that I am planning to build (just can't give up on that dream). So, retrofitting is not an issue, long run feasibility and reliability is.

I tried to remember details from the 5 pages in this thread, but am sure I didn't capture them all. Should be much easier with a diagram so I welcome any suggestions or critics (except for " just get a down jacket" or "why bother, pay professionals to do it for you".)

So, any additional valves, bleeders, bypasses?


Legend:
Aux. on the engine loop is for warming up the engine, rarely required and runs for not too long.

Raw water pump is to cool the engine or genset.

Aux. pump in the heating loop is to transfer heat from a running engine or genset.

Fresh/hot water pumps are obvious.

It's assumed both engine and genset have their own internal thermostats and coolant pumps.