All your heating needs.

[pmagowan]

OK, so what is the ultimate heating system for a 45 foot saily boat?

It would need to provide cabin heating and hot water heating for showers etc. I have an eberspacher hot air heater for the cabin at present and it is great. I was thinking it could even be used as a hair dryer to keep girls happy without eating electric. However, if you have this then you need a seperate system for hot water. The engine can provide some through a calorifier, electric can do some, and a seperate heatiung system can provide some but surely there must be an integrated solution to sort out all the heating needs? I have heard some people even add some solar thermal to the mix.

Boat use- summer cruising with occasional long distance adventure, high latitude stuff.

Thankee

 

[prv]

You want David2452 for this

However, my thought is that a diesel-fired hydronic (ie, water-based) system is the way to go for the sort of boat you have in mind. This is essentially the same idea as a domestic oil boiler, running on the boat's diesel supply.

With suitable plumbing you can heat the water tank, and for space heating you have a choice of small domestic-style radiators or "matrix heaters" which are water->air heat exchangers with fans that blow like the familiar hot-air systems. Boats with wheelhouses sometimes use these with suitable ducting for window demist too.

You could presumably plumb in the engine for hot water and heating from that source (though might be worth checking you can't over-cool it) and if you had any other sources of heat (solid fuel stove, non-electronic diesel stove a la Refleks) you could incorporate that too. I've even heard of people lining up the valves to pre-heat the engine before starting it!

Pete

 

[pmagowan]

Yes, I have heard about the engine preheat and I suppose that may be handy in high lattitudes, although most modern engines are so good it might not be an issue. I looked at the hydronic but I am concerned about the efficiency of hot air heater matrices. The eberspascher hot air heater is so good at blasting out a stream of lovely hot air I am not sure how a hot water to air exchanger could compete. The other idea I have is for a MVHR (mechanical ventilation heat recovery) unit which could use the hot air heating ducting. This would provide ventilation for the whole boat and can be used to keep it warm or cool but, maybe more importantly, it acts as a big dehumidifier.

It is like everything, a compromise. I want to know what is the absolute best when there might not be such a thing.

 

[David2452]

There are combination air / water heaters, the Webasto Dual Top for example but unsuitable for marine use as they do not take kindly to being anything other than level and are designed for motor homes when stationary only. Not a good idea to use an evaporator heater for just hot water as it will coke up due to light loading. You could go for a large matrix giving hot air and still heating your calorifier along with the engine heat, both from a water heater. I use that system on a regular basis albeit with radiators not matrix and it is very effective. There are all sorts of variations in use including any permutation (or indeed all of) of solar, solid fuel, diesel and heat source pumps but each one needs to be designed specifically for each aplication considering usage, budget, expectations etc.

 

[pmagowan]

There are combination air / water heaters, the Webasto Dual Top for example but unsuitable for marine use as they do not take kindly to being anything other than level and are designed for motor homes when stationary only. Not a good idea to use an evaporator heater for just hot water as it will coke up due to light loading. You could go for a large matrix giving hot air and still heating your calorifier along with the engine heat, both from a water heater. I use that system on a regular basis albeit with radiators not matrix and it is very effective. There are all sorts of variations in use including any permutation (or indeed all of) of solar, solid fuel, diesel and heat source pumps but each one needs to be designed specifically for each aplication considering usage, budget, expectations etc.

Thanks David, my expectations are high

One of the concerns I have with the hot water heaters is how responsive they are. The hot air is brilliant in that it is pretty instant and drys the boat out really well. I have no experience of hot water heating but I suspect that it wouldn't give such a dramatic performance. How good are the hot water to air matrices? I suppose the question is, do you try to get a fully integrated system or do you treat hot water and space heating seperately.

At home we have installed a wood gassifying boiler and this goes to an accumulator tank. Essentially the tank is a heat store and all your heat sources go to it and all you heat requirements come from it. It buffers the heat sources so that they can give optimum performance and you always have a store of heat. It doesn't lend itself to a yacht as it requires the water to stratify in the tank with hot on top and cool at the bottom but it does make me wonder if it is not possible to better integrate the solutions.

My current preference would be for a hot air heater for space heating and the engine and perhaps a dedicated hot water heater combination for DHW. The problem is that when motoring you could end up with loads of waste heat going into the sea and still be running the hot air space heating.

 

[David2452]

You are certainly right about the controllability, immediacy and freshening advantages of a hot air system, especially when using outside air instead of recirculatiing it. I think it is fairly well known among those that read my posts that I am not keen on Matrix installations, I have yet to find one that gives the performance close to what I would expect. Perhaps you could retain the blown system and consider a diesel heater for the domestic hot water, to reduce cycling and premature coking it would be possible to install a control on the water cylinder to shut down the heater at a given tank temperature instead of relying on the cycling of the boiler, also if that feature were used it would be acceptable to override the low setting on the boiler, further reducing coking.