Running rads straight from the engine

[IdealStandard]

I am trying to figure out a simple heating system from my water cooled engine. In an ideal world I would have a double coil calorifier, but I don't have the funds and just want a simple system to utilise a bit of heat which is otherwise wasted.

 

I was wondering if it is possible to run radiators directly off the enghine water system, using the engine pump to circulate the water. In theorty this seems like a simple and elegant system, but I am sure it is more complicated than that. Obviously this would only provide heat when the engine was running, but this would be adequate for now and I could always modify the system at a later date,

 

So....

 

what is stopping me from running a hose into the boat from the 'calorifier feed' from the engine cooling system, to a couple of radiators and then back again?

 

Many thanks

 

Tim

[Bobbybass]

Without thinking about it much...if you were just asking me that for an opinion....I can't think of any problems..

[IdealStandard]

Without thinking about it much...if you were just asking me that for an opinion....I can't think of any problems..

 

That's my kind of answer!

 

My main concern is whether it would affect the engine cooling.

[grahame r]

I think you've already identified the main drawback. You mostly want heat in the evening and early morning when you shouldn't be running the engine for that purpose. Going to all the trouble of installing rads etc seems like a lot of work for little return. Stoves are loverly.

[matty40s]

Good recent thread here covering it.

rads from engine - biggles

[IdealStandard]

I think you've already identified the main drawback. You mostly want heat in the evening and early morning when you shouldn't be running the engine for that purpose. Going to all the trouble of installing rads etc seems like a lot of work for little return. Stoves are loverly.

 

I've got a multi fuel stove, which is currently my only source of heat on a 57ft boat. I absolutely love it and it is definitely the best source of ehating, but it doesn't heat the bedroom which is below the stove and doesn't seem quite capable of keeping the boat warm. In the recent heavy frost the condensation inside the boat froze on the windows.

 

Granted there is plenty more draight stripping and insulation to be done and the boat is quite shell like atm, but I am looking at options. There are twin thermostats, so in theory if the domestic system is stopping the cooling, the second thermostat will open and the skin tank will continue to cool the engine.

[nb Innisfree]

Once the engine is up to operating temp then it's ok to bring in the CH circuit but having this circuit operating straight from engine start will result in engine taking ages to reach temp which 'aint good for it.

[Kwacker]

I've often thought about using the heater/fan assembly from a scrap car to provide quick, blown heat. I figured that I could tap into the calorifier circuit.

[blackrose]

 

what is stopping me from running a hose into the boat from the 'calorifier feed' from the engine cooling system, to a couple of radiators and then back again?

 

 

You have to remember that most engine water pumps are more like "stirrers" than real pumps so it might be asking quite a lot to expect one to pump coolant around your entire CH system. Hence the inclusion of a heat exchanger and separate 12v pump on my engine/CH system as described in Biggles' thread.

[IdealStandard]

Once the engine is up to operating temp then it's ok to bring in the CH circuit but having this circuit operating straight from engine start will result in engine taking ages to reach temp which 'aint good for it.

 

Isn't that the job of the thermostat? Water will only be pumped out of the calorifier outlet when it reaches 76 C on the system.

 

 

The way I see this system is essentially installing radiators as I refit the boat which is currently half stripped. With a CH system in place, I can take the inlet directly from the engine for the time being and in future could isntall a calorifier to power the same CH system.

 

Good recent thread here covering it.

rads from engine - biggles

 

That thread is great. Makes very useful reading.

 

If a mod wanted to delete this thread, I think all the info I need is in the thread Biggles started.

 

Blackrose I may well copy your system, it looks spot on.

[blackrose]

I think you've already identified the main drawback. You mostly want heat in the evening and early morning when you shouldn't be running the engine for that purpose. Going to all the trouble of installing rads etc seems like a lot of work for little return. Stoves are loverly.

 

The two are not mutually exclusive. I have a stove and a CH system I can run from the engine.

 

Why do you say a CH system offers little return? Plenty of people have radiators on their boats, heated from stoves, diesel heaters and from their engines.

 

I'd have thought that the benefits of an CH system run from the engine would be rather obvious. It means that you can heat the boat while you're on the move, utilising free heat from the engine and without using any other expensive fuel. Sometimes it's good for those who aren't steering to be able to go inside a nice warm boat.

Edited November 16, 2012 by blackrose

[nb Innisfree]

Isn't that the job of the thermostat? Water will only be pumped out of the calorifier outlet when it reaches 76 C on the system.

 

Yes you're right if your takeoff is after the t/stat but most are before the t/stat like car heaters.

[Proper Job]

I've got a great big green 1 ton radiator just infront of the bed room.

 

It keeps it nice and toasty after a days cruising - Summer or Winter

 

 

On a serious note, becareful you don't over load the engine circ pump. The pressure loss running the cooling water around rads may cause problems with circulation around the engine.

Edited November 16, 2012 by Proper Job

[David Schweizer]

The radiators on our boat are fed directly from the Cab heater connections on the engine. Apart from the radiator junctions, there are alsdo two T junctions off the feed and return pipes to an elderly Ellis heatmaster gas boiler and a single coil calorifier.

 

You need to satisfy yourself that the Engine pump is powerfull enough to ensure adequate circulation, (the BMC 1.5 /1.8 water pumps are fine)but if it your engine is based upon a commercial vehicle unit it should be ok. The only other design issues that need to be considered are the ability to cut off the supply of heat to the radiators in the summer, for which I have installed two gate valves, and the need for a pressurized expansion tank somewhere in the system to absorb the increased volume of hot water. If your engine has a Bowman expansion tank, that will probably be ok but an additional tank on the feed circuit preferferably just befor the radiator further from the engine will help prevent air locks. Get one that will take a standard AC metal pressure cap so that the correct value for your engine can be fitted.

 

ASAP used to stock one suitable for boats, but they do not seem to list them any more however, there are lots of different types on eBay, the sort of thing you need is like this:-

 

 

If you are also planning to have a calorifier in the system it is a good idea to install a one way valve in the supply pipe between the engine and calorifier coil to help prevent heat feeding back into the engine overnight.

Edited November 16, 2012 by David Schweizer

[grahame r]

I've got a multi fuel stove, which is currently my only source of heat on a 57ft boat. I absolutely love it and it is definitely the best source of ehating, but it doesn't heat the bedroom which is below the stove and doesn't seem quite capable of keeping the boat warm. In the recent heavy frost the condensation inside the boat froze on the windows.

 

Granted there is plenty more draight stripping and insulation to be done and the boat is quite shell like atm, but I am looking at options. There are twin thermostats, so in theory if the domestic system is stopping the cooling, the second thermostat will open and the skin tank will continue to cool the engine.

 

Perhaps a pumped back boiler system would be a more practical answer?

 

The two are not mutually exclusive. I have a stove and a CH system I can run from the engine.

 

Why do you say a CH system offers little return? Plenty of people have radiators on their boats, heated from stoves, diesel heaters and from their engines.

 

I'd have thought that the benefits of an CH system run from the engine would be rather obvious. It means that you can heat the boat while you're on the move, utilising free heat from the engine and without using any other expensive fuel. Sometimes it's good for those who aren't steering to be able to go inside a nice warm boat.

 

I too have CH + a stove. I meant that the rads offer little return if you can only use them whilst the engine is running. Bedrooms do tend to need heating when engines shoudn't be running.

[nb Innisfree]

Our system here might help you to work out some circuits of your own. Because we don't have a pressure header tank we run the whole thing unpressurised. There is a bypass valve to confine circuit to engine and Mikuni only, or, utilising this valve and isolating valves we can isolate the engine and run it in standard pressurised mode in case the CH or Mikuni circuit sprang a leak or some other problem

 

[Chalky]

You have to remember that most engine water pumps are more like "stirrers" than real pumps so it might be asking quite a lot to expect one to pump coolant around your entire CH system. Hence the inclusion of a heat exchanger and separate 12v pump on my engine/CH system as described in Biggles' thread.

 

I did some research about this before I installed our system. The pump on our Isuzu can only "pump" a very short distance and couldn't do the boat heating circuit. I also spoke to some of our engine designers and their advice was to use a secondary pump and heat exchanger. I used a water to water heat exchanger off a combi boiler that I bought off ebay for £10 and an engine auxiliary coolant pump that I got from a scrap yard.

[nb Innisfree]

For the record the water pump on our LPWS4 manages to circulate 6 rads and 2 cals.

[smileypete]

So....

 

what is stopping me from running a hose into the boat from the 'calorifier feed' from the engine cooling system, to a couple of radiators and then back again?

For that sort of thing I'd consider a car heater matrix (works well enough for cars funnily enough ) and can be surprisingly cheap:

 

http://www.ebay.co.uk/itm/170378256484

 

Slap some 12V PC fans to it for a try out, maybe even get a proper heater blower, possibly cheaper from a scrappie:

 

http://www.ebay.co.uk/itm/321018786645

 

Nice thing about a blower like that is it can be ducted to the steering position.

 

As others have said, engine pumps MAY be low pressure high flow, so the pipes might ideally need to be reasonably wider than say 15mm bore unless it's a short run.

 

cheers, Pete.

~smpt~

Edited November 16, 2012 by smileypete

[Paul C]

We have 3x radiators (and the calorifier) fed from the engine coolant.

 

- make sure the pipes are suitably large, instead of/as well as relying on a decent pump. Ours are 22mm.

- yes the rads do get hot! But of course, in spring/autumn you only want them to come on after around 8pm....which is awkward.....probably the biggest issue with the setup

- we had a diesel stove with a back boiler at the front of the boat too, all feeding the one coolant circuit. So in winter, it heated the engine as well as the radiators and calorifier. Whether this is a good or bad thing, I don't know. But we have ditched this, for a (no back boiler) solid fuel stove. We just disconnected the pipes and joined them with some pipe, in an accessible position (not behind the fire surround).

- in the winter, its handy to keep the rads on, keep the doors closed and let the boat interior get warm. It can't get it 'hot' but gets it warm enough for daytime use.

[blackrose]

Perhaps a pumped back boiler system would be a more practical answer?

 

 

 

I too have CH + a stove. I meant that the rads offer little return if you can only use them whilst the engine is running. Bedrooms do tend to need heating when engines shoudn't be running.

 

I see, but you can have the same rads run from both engine/heat exhanger and backboiler without too much plumbing. Mine is about to be plumbed this way.

 

We have 3x radiators (and the calorifier) fed from the engine coolant.

 

- make sure the pipes are suitably large, instead of/as well as relying on a decent pump. Ours are 22mm.

- yes the rads do get hot! But of course, in spring/autumn you only want them to come on after around 8pm....which is awkward.....probably the biggest issue with the setup

 

Which is why the heat exchanger and independent pump is better. You can switch the CH system on or off with the pump.

[Paul C]

I see, but you can have the same rads run from both engine/heat exhanger and backboiler without too much plumbing. Mine is about to be plumbed this way.

 

 

 

Which is why the heat exchanger and independent pump is better. You can switch the CH system on or off with the pump.

 

Which issue does the heat exchanger and pump fix?? In the autumn, it was too hot to turn the rads on before around 8pm (still in T shirts, with windows open) but the temperature dropped quite a lot in the night.

 

I forgot to mention we also have a CH pump. The engine coolant pump gives approx the same flow as the separate pump, so when running engine, no need for it. When not running engine but using back boiler, you can run the pump if the stove is turned up high. I think it was plumbed to be gravity fed too, ie turn the stove low enough and the pump doesn't need to run.

[davidc]

I've often thought about using the heater/fan assembly from a scrap car to provide quick, blown heat. I figured that I could tap into the calorifier circuit.

 

 

Waterways world issue December 2011

 

Has an article on free heat using a car heater matrix

Quite a good article

 

If you cannot get a hold of it pm me I’ll email you a copy

[IdealStandard]

Another very interesting option is an exhaust heat exchanger

 

http://polarpowerinc.com/Heat_Exchanger.pdf