Efficient Diesel Heating

I've got a Webasto fitted to a boat I bought recently ... only tried it once but it was a bit whiffy for a couple of minutes so I turned it off again! Does the smell diminish? Luckily I've got reverse cycle aircon as well. In a caravan I've got Alde wet central heating which is very efficient ... this is what boats should have by now.
 
Many people don't like gas heaters, which goes against the Alde system, though a similar set-up using the Hydronic would be just as good. Incidentally, there are two types of Hydronic. One is meant for independant pre-heating of a vehicle engine and heating system so it has an in-built pump whereas the other is an auxiliary heat source without a pump, so you'd need to adda pump. For me the idea of central heating is attractive as the water pipes would be much easier to route around the boat's hidden spaces than an air duct, but as the accomodation is "compact" there's not much space for radiators which would mean siting a matix blower somewhere - just as difficult.

Rob.
 
michaelchapman said:
But it is efficient - if you use the heat from the generator to heat the water as well.

Actually the real problem might me that you need a rather small generator to make this work.
A 4KW generator will at 75% load generator generate 3KW of electricity and about 6KW of heat of which you could probably recover up to 4.5 - 5KW through the heat exchanger.

You need a rather big yacht to need that amount of continuous heating. And that rather big yacht probably has a much bigger generator........
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Most yachts don't have generators so the Diesel heating is a much more efficient use of space then fitting a generator as well.
Even on a boat with a generator its also an advantage to be able to heat the boat without the generator running.
 
Kingfisher 3 said:
In a caravan I've got Alde wet central heating which is very efficient ... this is what boats should have by now.
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We have the Alde 3020 in our camper but I don't think that you could carry enough gas in the average boat; we can burn 6Kg. in a cold weekend.
 
Steve_N said:
I'm sure that there have been warnings posted in the past (from our resident Eber dealer/expert whose name I can't recall) that you must not fit the Eber exhaust silencer in a boat installation because its simple crimped construction means that it isn't gas-tight. It was designed for mounting underneath vehicles and would be dangerous inside a boat - possible CO poisoning etc.
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That warning would have been centred on vehicle silencers which are not only crimped but have a deliberate hole in them. The correct marine one is much larger and quiter, it is also gas tight and comes complete with the flexi exhaust tube to keep joints to a minimum.
 
rob2 said:
Incidentally, there are two types of Hydronic. One is meant for independant pre-heating of a vehicle engine and heating system so it has an in-built pump whereas the other is an auxiliary heat source without a pump, so you'd need to adda pump.
Rob.
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There is only one marine hydronic type heater, both Webasto and Eber, the two you alude to are vehicle pre and auxilliary heaters and both have a different ECU to the marine / motor caravan version which has, among other things a much better voltage tolerance, very popular on narrowboats and widebeams and I reckon I fit at least as many wet systems as blown air systems these days.
 
One of the major advantages of ducted air systems is that the heat is instantaneous - great when you come in after a cold sail, or a cold walk ashore.
My Eberspacher gets heavy use, and since I started to burn low sulphur fuel, it has worked faultlessly.
When motoring, I can make use of the waste heat by passing it through a matrix, through which air is ducted via an in-line fan, but I can imagine few things less efficient than running an engine, merely to use the waste heat.
 
A diesel generator under load of 75% - 85% is about 34-40% efficient in converting diesel fuel into electricity. Converting electricity into heat is pretty close to 100% efficient. Using the heat of the generator to heat the water raises the total efficiency of the system to 80-85% for small systems.

Electricity generator stations combined with district heating do a bit better than this at the output from the plant (i.e. not counting for losses in getting the heat and electricity to where it is needed).

A normal domestic boiler is about 85% efficient in converting the fuel into heat inside your home (presumably the rest goes up the flue).

This would seem to imply that you get the same efficiency as a good diesel heating system by using the waste heat from the generator combined with using the electricity for something useful - even if that is only to power the electric part of the heater!

Does that add up, or is there a big misunderstanding somewhere?

(No - I don't have a generator, and even if I did the noise would drive me nuts, but that is not what I was asking)
 
michaelchapman said:
A diesel generator under load of 75% - 85% is about 34-40% efficient in converting diesel fuel into electricity. Converting electricity into heat is pretty close to 100% efficient. Using the heat of the generator to heat the water raises the total efficiency of the system to 80-85% for small systems.

Electricity generator stations combined with district heating do a bit better than this at the output from the plant (i.e. not counting for losses in getting the heat and electricity to where it is needed).

A normal domestic boiler is about 85% efficient in converting the fuel into heat inside your home (presumably the rest goes up the flue).

This would seem to imply that you get the same efficiency as a good diesel heating system by using the waste heat from the generator combined with using the electricity for something useful - even if that is only to power the electric part of the heater!

Does that add up, or is there a big misunderstanding somewhere?

(No - I don't have a generator, and even if I did the noise would drive me nuts, but that is not what I was asking)
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You are right but if you are not using the electrical energy from the generator, just the waste heat, you would be more efficient with an eberspacher or similar heater.

Colin www.solocoastalsailing.co.UK
 
NormanS said:
One of the major advantages of ducted air systems is that the heat is instantaneous - great when you come in after a cold sail, or a cold walk ashore.
My Eberspacher gets heavy use, and since I started to burn low sulphur fuel, it has worked faultlessly.
When motoring, I can make use of the waste heat by passing it through a matrix, through which air is ducted via an in-line fan, but I can imagine few things less efficient than running an engine, merely to use the waste heat.
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Agree that ducted warm air systems are quick to deliver heat, a lot quicker that the waste heat from a generator started from cold.

The other benefit of the hot air eberspacher type heaters is that the hot air is from outside the cabin which forces out the moisture laden air and so reduces the condensation in the cabin. A wet system with radiators would heat the existing moist air in the cabin so you may get more condensation on cold surfaces.

Colin. Www.solocoastalsailing.co.uk
 
If you have a generator and want heating from it would you not just plug in an electric radiator or fan heater ?
.
 
I've always liked the idea of a Refleks type heater on a smallish boat. Silent, no elec consumption, reliable. Ideal at anchor but can't be used underway so no good for serious passage making.
 
ghostlymoron said:
I've always liked the idea of a Refleks type heater on a smallish boat. Silent, no elec consumption, reliable. Ideal at anchor but can't be used underway so no good for serious passage making.
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I imagine that they need a balanced flue, as does my Sigmar heater, although Refleks heaters are used on many older type fishing vessels so it's surprising that they are not happy in the wind. I wanted a visible flame but the Reflex ones were too large for my boat which is why I bought the Sigmar100. I also have a Webasto which is brilliant for instant heat and uses little electrikery.
Samphire stoves have a clever solution ... The inlet air is drawn down the outside of the double skinned chimney, so you get a balanced flue.
Unfortunately their website is being upgraded so no link apart from images.
 
Steve_N said:
I'm sure that there have been warnings posted in the past (from our resident Eber dealer/expert whose name I can't recall) that you must not fit the Eber exhaust silencer in a boat installation because its simple crimped construction means that it isn't gas-tight. It was designed for mounting underneath vehicles and would be dangerous inside a boat - possible CO poisoning etc.
Click to expand...

And you should not draw in air for circulation from the same compartment in which the burner unit is installed. 100% of all ones I have seen - professionally installed draw air from the same compartment! (Including mine)
 
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