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Bought a car heater for boat


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I've bought this car heater matrix for my Aintree Beetle narrowboat, going to plumb from the calorifier return feed to the engine to use the hot coolant water to blow hot air into the cabin whilst on the move.

 

https://www.carbuilder.com/uk/all-in-one-compact-car-heater-with-vents-and-valve

 

I notice a few things, 4.3kw heat output - nice and toasty? Also it draws 5.8 amps from the battery and is 75 watts, will this be ok for when the engine is running?

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If you plumb it in like that you will lose your heat to the calorifier as well when you switch the heater off. Either fit a 3 way valve or plumb it in parallel. Shouldn't be an electrical issue when running unless the boat is only ticking over for a long time.

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5 minutes ago, Mike Adams said:

If you plumb it in like that you will lose your heat to the calorifier as well when you switch the heater off. Either fit a 3 way valve or plumb it in parallel. Shouldn't be an electrical issue when running unless the boat is only ticking over for a long time.

This is the bit that confuses me. I thought the heat loss to the calorifier would be caused by plumbing it into the engine>calorifier pipe, rather than the return pipe from the calorifier back to the engine? As heat would be lost while the hot water travels to the heater before it reaches the calorifier.

 

I know about the manual 3-way valve though, was thinking of fitting one to the system.

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I think these heaters control the heat by reducing the flow through the cable operated valve. If the valve is shut, ie when the heater is mechanically set to off there will be no flow though the heater and the calorifier. I would connect in in parallel with the calorifier. Hope this helps. I did my heated towel rail like this and it was fine.

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We fitted a few heaters similar to this on new builds. 
 

We used a 12v solenoid diverter valve triggered by a thermistor set at about 60c. When the engine was up to temp the valve opened and water flowed round the heater matrix. 
 

Also fitted another thermistor on the matrix itself so the fan only operated when it was hot...together with an override switch. 

Edited by frangar
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1 hour ago, Mike Adams said:

If you plumb it in like that you will lose your heat to the calorifier as well when you switch the heater off. Either fit a 3 way valve or plumb it in parallel. Shouldn't be an electrical issue when running unless the boat is only ticking over for a long time.

Thanks. Are these two diagrams good to follow? (minus the radiator and calorifier balancing valve)

waterheaterpipes02_big.jpg

waterheaterpipes01_big 2.jpg

Edited by Philip
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If you intend to use engine heat then why are your diagrams showing a boiler and header tank? I think that you are trying to overthink this. You don't want heat in the summer so why not fit an L split three port valve between the calorifier and heater so in summer the water simply bypasses the heater to a T close to the heater outlet.

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We have a similar thing in our lounge but it has no cable operated water valve. It is plumbed in parallel with the calorifier with no control valves whatsoever.

 

As long as I don't switch the fan on until the calorifier has got up to temperature everything works well.

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6 minutes ago, Tony Brooks said:

If you intend to use engine heat then why are your diagrams showing a boiler and header tank? I think that you are trying to overthink this. You don't want heat in the summer so why not fit an L split three port valve between the calorifier and heater so in summer the water simply bypasses the heater to a T close to the heater outlet.

These were diagrams I found on google.

 

To simplify:

 

Engine > 3-way diverter valve > calorifier or heater or both > Return pipe from calorifier back to engine with T from heater matrix return pipe inserted.

 

This look about right?

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yes, if it what you want to do but @pearley's solution is simpler. If in winter you find the engine runs cool and takes ages to warm up you may want to fit a restricting valve in the calorifier feed to reduce the heat being lost from the engine but I don't think it will be needed so its try it and see. The heater matrix will extend the engine warm up time and the time taken to get the hot water and matrix output up to temperature. I doubt this sill be a problem.

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I've got a short length of Finrad on the calorifier return (and another on the radiator return) in the bottom of a full height cupboard.  Used for airing/ drying coats and clothes.  I've got valves that can let me select rads/cal/both and still works well if only the calorifer is being heated.

 

You can find old-fashioned heater matrixes (I'm thinking A35) that don't have any restrictions to the flow which would work in a similar way.  Wouldn't want anything in the calorifier circuit that affected the flow.

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I have a small towel radiator in my cauliflower return. Each leg  is fed from a tee in the return hose, each with a full bore 15mm ball valve so it can be isolated, and a full bore bypass ball valve between the tees so I can control the flow. Actually, with all valves fully open so the radiator is in parallel with the return pipework, I was surprised to find it works perfectly well, so it stays like that. No additional resistance in the cauliflower return (a bit ess actually I suppose) and a nice hot little towel rail giving free heat in the bathroom when cruising.

 

I suspect you'd find the same with your new heater circuit if plumbed the same way and then it wouldn't matter if your heater cuts flow when it shuts down as the bypass will allow the calorifier return to flow as freely as before. You have full flexibility with the valves if you find adjustment or re plumbing is required. Do get the slightly more expensive full bore valves though - the standard 15mm ball valves are restrictive.

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2 hours ago, Sea Dog said:

I have a small towel radiator in my cauliflower return. Each leg  is fed from a tee in the return hose, each with a full bore 15mm ball valve so it can be isolated, and a full bore bypass ball valve between the tees so I can control the flow. Actually, with all valves fully open so the radiator is in parallel with the return pipework, I was surprised to find it works perfectly well, so it stays like that. No additional resistance in the cauliflower return (a bit ess actually I suppose) and a nice hot little towel rail giving free heat in the bathroom when cruising.

 

I suspect you'd find the same with your new heater circuit if plumbed the same way and then it wouldn't matter if your heater cuts flow when it shuts down as the bypass will allow the calorifier return to flow as freely as before. You have full flexibility with the valves if you find adjustment or re plumbing is required. Do get the slightly more expensive full bore valves though - the standard 15mm ball valves are restrictive.

 

Thanks, excellent info! 

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2 hours ago, roland elsdon said:

Best way of warming up boat go boating

Ain't that the truth! Its the best thing for everything with a boat but it sometimes seems, as Michael Caine might say: "Not a lot of people know that!" :detective:

 

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In terms of location I'm thinking of either putting the unit in one of the step hatches at the back, or in the hatch under the rear dinette seat. But to work properly it would need a vent to draw air from outside into the hatch. I know this means drilling a hole in the side of the boat, so how big should the hole be to draw sufficient air from outside? 

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17 minutes ago, Philip said:

In terms of location I'm thinking of either putting the unit in one of the step hatches at the back, or in the hatch under the rear dinette seat. But to work properly it would need a vent to draw air from outside into the hatch. I know this means drilling a hole in the side of the boat, so how big should the hole be to draw sufficient air from outside? 

Personally I would rather draw the air from inside the boat so it already has some heat in it rather than blowing air from outside in which in turn means you will be venting some of your hot air through the cabin vents. If i could work out a way of drawing it from further along the boat so much the better for heat circulation.

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30 minutes ago, Tony Brooks said:

Personally I would rather draw the air from inside the boat so it already has some heat in it rather than blowing air from outside in which in turn means you will be venting some of your hot air through the cabin vents. If i could work out a way of drawing it from further along the boat so much the better for heat circulation.

I go along with Tony, its not like you are trying to demist a windsreen. Why heat cold air when you can heat warm?

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I was thinking about condensation and blowing dry air directly from the outside through the boat to help with this. But the boat is well vented anyway so perhaps this isn't much of an issue. One of the rear step hatches has a vent in it, as does the dinette seat hatch, so if I put the matrix in either of these then this could draw air in from the cabin. Here's a picture...

 

 

20201024_134120.jpg

Edited by Philip
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