Engine circulation water for cabin heating

[Graham_Wright]

I think this has been discussed before but I can't find a reference.

Now winter is approaching and it is cold on the mooring, it seems sense to use that waste heat while charging the batteries.

There are many matrices available on ebay. Just (!) needs a fan.

What's to do?

 

[maby]

I guess it depends on how long you run your engine for each day. A proper circulated hot water driven heating system with a diesel fired boiler is one thing - a viable alternative to a blown air Webasto or similar - but it does seem like rather a large amount of work and expense simply to take advantage of waste heat from the engine running one or two hours per day. Presumably, you would still need a more standard heating solution to stop you freezing once the batteries have charged and the engine is stopped?

 

[Graham_Wright]

I guess it depends on how long you run your engine for each day. A proper circulated hot water driven heating system with a diesel fired boiler is one thing - a viable alternative to a blown air Webasto or similar - but it does seem like rather a large amount of work and expense simply to take advantage of waste heat from the engine running one or two hours per day. Presumably, you would still need a more standard heating solution to stop you freezing once the batteries have charged and the engine is stopped?

I intend to use an Eber as well but that is for the future. For the present, and bearing in mind that the clarifier is already heated by engine circulation water, why not extend it a bit?

The installation seems to be a couple of hoses, a matrix for around £30-£40 and a fan.

Am I naive?

 

[NormanS]

I have a motor-sailer ketch, and sometimes we motor using the inside helm. Every motor vehicle has heating from waste heat from the engine, so I decided that it was well worth while doing something similar for the boat. I got a heater matrix, from a Transit, from a car scrapper, (two for £10), a suitable fan to accept ducting. I plumbed the matrix into the calorifier pipework. Mine is unsophisticated, either on or off, and works brilliantly.

 

[lw395]

You need to be loading the engine, not just charging batteries, to produce any useful heat.
I tried this ages ago with a 3GM30, idling and pottering in the harbour, heat output was such a disappointment, I bought an eberspacher PDQ. Waste heat seems to increase suddenly at maybe 4.5knots?
Motorsailing, sod all heat.
To be fair, that boat was possibly underpropped.

IIRC that was with the coolant going to the calorifier first, normally if we used the engine we didn't muck about, a few minutes against the tide gave us hot water. bimbling around got the engine up to temp but very little in the calorifier.

But ex-vehicle eberbastos are cheap enough, you won't regret the matrix, but you might find the job extends to a heater.

 

[NormanS]

Hmm. How did your engine know that you were going against the tide?

 

[lw395]

Hmm. How did your engine know that you were going against the tide?

When we go against the tide, we don't prat about doing 1kt more than the tide, we get on with it. Going against the tide in Portsmouth and off Gilkicker etc, you're not worried about making a bit of wash, it's max cruising revs. I wouldn't drive the boat like that near other people's moored boats etc up harbour or in a typical river. Or going with the tide, there's no need.

Some diesel cars have electric heater elements in the matrix or plumbing, for demisting at idle. I considered this, but our alternator was not really up to it at that time. Not sure what the wattage would be, long time since I looked into it TBH.

 

[Graham_Wright]

When we go against the tide, we don't prat about doing 1kt more than the tide, we get on with it. Going against the tide in Portsmouth and off Gilkicker etc, you're not worried about making a bit of wash, it's max cruising revs. I wouldn't drive the boat like that near other people's moored boats etc up harbour or in a typical river. Or going with the tide, there's no need.

Some diesel cars have electric heater elements in the matrix or plumbing, for demisting at idle. I considered this, but our alternator was not really up to it at that time. Not sure what the wattage would be, long time since I looked into it TBH.

I have tried using a 1kW fan heater off the batteries while the engine is running. Unfortunately, the breaker supplying the inverter tripped out. I think it might succeed if I parallel the inputs. The alternator sources 130 amps.

However, that seems a ham-fisted way of going about it. I will seek a suitably sized matrix and do an experiment.

 

[tillergirl]

https://www.kuranda.co.uk/kalori-he...x-units/kalori-silencio-fai-kk12014081-kalori

 

[pvb]

https://www.kuranda.co.uk/kalori-he...x-units/kalori-silencio-fai-kk12014081-kalori

That heater is way cheaper at Butler Technik, £96 vs £143 - https://www.butlertechnik.com/insta...nger-matrix-12v-silencio-1-7kw-12014081-p1354

If anyone's interested in this type of matrix heater, be aware that the heat output quoted is a maximum, usually based on the water temperature being 100degC higher than the air temp. This sort of differential is unlikely to be reached in a boat installation, so heat output will be reduced. Additionally, they need maximum fan speed to get the best heating, so they can be noisy. The secret is to overspecify the heater; I seem to remember there was a poster here who'd fitted an 8kW matrix heater which gave reasonable heat, but he didn't think it was anywhere near 8kW.

 

[lw395]

That heater is way cheaper at Butler Technik, £96 vs £143 - https://www.butlertechnik.com/insta...nger-matrix-12v-silencio-1-7kw-12014081-p1354

If anyone's interested in this type of matrix heater, be aware that the heat output quoted is a maximum, usually based on the water temperature being 100degC higher than the air temp. This sort of differential is unlikely to be reached in a boat installation, so heat output will be reduced. Additionally, they need maximum fan speed to get the best heating, so they can be noisy. The secret is to overspecify the heater; I seem to remember there was a poster here who'd fitted an 8kW matrix heater which gave reasonable heat, but he didn't think it was anywhere near 8kW.

True.
If you want to put say 1kW into the air, you need to either have a hot matrix or shift a lot of air.
If the water in the matrix is at 90, the matrix will be at say 80 and the incoming air maybe 20. The outgoing air might be at 55 if you're lucky. So delta t of the air is 35. The heat capacity of air is not huge, so you need a lot of cubic metres of air moving.
My first experiment was to buy a heater from a VW Polo from a local breaker.
Two flaws with this, the matrix had very fine fins, to give enough surface area to transfer the heat, so stifled air flow.
And the fan that came with it drew about 12A at full chat IIRC.
The second flaw was that it's big lump, not easy to build into a boat.

But once you get it warm ,you don't need that many kW to keep a boat warm.

The other problem I had was that poor matrices which struggled to get rid of the heat caused the eber to short cycle, which made it grumpy. I solved that by letting it heat the engine and calorifier as well, which slowed the cycling and worked like a big storage heater. Ths may be why the diesel-air heaters are a nice simple solution and people like them....

 

[NormanS]

That heater is way cheaper at Butler Technik, £96 vs £143 - https://www.butlertechnik.com/insta...nger-matrix-12v-silencio-1-7kw-12014081-p1354

If anyone's interested in this type of matrix heater, be aware that the heat output quoted is a maximum, usually based on the water temperature being 100degC higher than the air temp. This sort of differential is unlikely to be reached in a boat installation, so heat output will be reduced. Additionally, they need maximum fan speed to get the best heating, so they can be noisy. The secret is to overspecify the heater; I seem to remember there was a poster here who'd fitted an 8kW matrix heater which gave reasonable heat, but he didn't think it was anywhere near 8kW.

Presumably we're still talking about using waste heat from the engine? If so, unless it was a big or fast motor boat with a powerful engine, you would hope that it wasn't producing nearly as much as 8kw of waste heat. I have no way of measuring the output from my system, but would guess from comparing it to a fan heater, or to my 4kw Eberspacher, that it's about 3-4 kW. It makes a huge difference if motoring in cold weather.