Radiator heating via engine

[Tony Brooks]

Just now, ditchcrawler said:

Our share boat with an eberspacher the engine cooling and heating system were all on one circuit, one header tank, it even included a back boiler. As well as the eberspacher it had a second pump which would pump hot water from the stove or the engine round the rads, the Eberspacher would heat the engine as well  

On assumes then that the engine ran unpressurised. That is probably fine for canal work but if it even got onto a river with a bit of flow on you might (not will) get localised boiling on internal hot spots and that will allow a build up of internal scale and expel coolant so the engine then suffers normal overheating. nothing wrong with such a system as long as any down sides are known and accepted.

[ditchcrawler]

2 minutes ago, Tony Brooks said:

On assumes then that the engine ran unpressurised. That is probably fine for canal work but if it even got onto a river with a bit of flow on you might (not will) get localised boiling on internal hot spots and that will allow a build up of internal scale and expel coolant so the engine then suffers normal overheating. nothing wrong with such a system as long as any down sides are known and accepted.

No the whole system ran at engine pressure. We had it for 8 years with no problem

 

[WhiteSuit]

19 minutes ago, Tony Brooks said:

If you just want the chill off the rads then the calorifier will act as a heat exchanger with the central heating pump running

This is what we do, once calorifier is at temperature switch pump on which puts limited heat through roads to take chill off when not too cold. Remember to switch pump off half an hour before stopping cruising to ensure calorifier is at good temperature for showers etc.

If its colder use the stove anyway

Edited September 11, 2020 by WhiteSuit
Edit to say with a Mikuni

[Sea Dog]

4 minutes ago, ditchcrawler said:

Our share boat with an eberspacher the engine cooling and heating system were all on one circuit, one header tank, it even included a back boiler. As well as the eberspacher it had a second pump which would pump hot water from the stove or the engine round the rads, the Eberspacher would heat the engine as well  

My engine cooling circuit already takes 30 odd litres of coolant. Adding the heating circuit to that would add to my 5 annual draining and disposal nightmare. Plus, you're now building in a single point of failure, any burst pipe or similar defect affecting both keeping you warm and running your engine. If you must have a link, use a heat exchanger (although I still think that's overkill). 

[Tony Brooks]

Just now, ditchcrawler said:

No the whole system ran at engine pressure. We had it for 8 years with no problem

 

In that case with a stove I think it was dangerous. No problem if there was no stove or the stove had thermostatic plus overheat control.

[ditchcrawler]

Just now, Sea Dog said:

My engine cooling circuit already takes 30 odd litres of coolant. Adding the heating circuit to that would add to my 5 annual draining and disposal nightmare. Plus, you're now building in a single point of failure, any burst pipe or similar defect affecting both keeping you warm and running your engine. If you must have a link, use a heat exchanger (although I still think that's overkill). 

O I think you are right, but being a share boat I didn't have the problem of cooling changes, We did have to have the header tank empty when cold so that it didn't overflow

1 minute ago, Tony Brooks said:

In that case with a stove I think it was dangerous. No problem if there was no stove or the stove had thermostatic plus overheat control.

I wouldn't install a system like that, I would only have a have a gravity system on an open fire 

[Tony Brooks]

2 minutes ago, ditchcrawler said:

I wouldn't install a system like that, I would only have a have a gravity system on an open fire 

On that we can agree.

[Tracy D'arth]

How can you ensure that the engine is topped up when you can't take the cap off without emptying the heating system?

 

 I think using a plate heat exchanger and keeping the systems separate is far better and safer than a solid fuel boiler with no thermostat control running on a pumped sealed system.

[dor]

1 hour ago, Tony Brooks said:

 

If you just want the chill off the rads then the calorifier will act as a heat exchanger with the central heating pump running.

This is what I have.  A switched supply to the ch pump. Doesn’t get the rads as hot as the heating, but as Tony says, enough to take the chill off.

 And all the plumbing is already in place.

[nicknorman]

I installed this on our boat a few years ago. No idea why it isn’t more common because it is great to have “free heat” whilst cruising in cold weather.

 

Plate heat exchanger on the 28mm pipe to skin tank. I was a bit worried about the heat exchanger restricting flow and hence cooling at high power, so installed a 28mm bypass pipe normally closed by a gate valve. However, I have never needed to open the gate valve to bypass the exchanger including when cruising at 2200 rpm for hours up the tidal Trent.
 

Other side of the heat exchanger plumbed into the Mikuni radiator system, using a small 12v pump and a low opening pressure 1-way valve, both from Solarproject.

 

Then added another 1-way valve in the output from the Mikuni. The 1-way valves allow either the Mikuni or engine heat exchanger to supply heat, without that hot water back flowing through the other device and wasting heat.

 

With the engine running slowly (flights of locks etc) the rads don’t get beyond very warm, but normal cruising they get hot, though not as hot as with the Mikuni. It certainly makes the inside of the boat very cosy.

 

My tip would be to not undersize the plate heat exchanger. The one I got is specced at I think 20kw, which sounds a lot but if you read the small print that much heat transfer is with a very large difference between input and output temperature. Since heat is only transferred when there is a temperature difference between input and output, and you want the highest temperature possible, and the engine doesn’t run that hot, it is best to spec a plate exchanger with a very high kw rating. My one is on the small size, I should have got a bigger one.

 

Something like this, for the plate heat exchanger. You want one with connection stubs on it, not one designed to plug into a domestic boiler.

 

https://www.ebay.co.uk/itm/Stainless-steel-PLATE-HEAT-EXCHANGER-NORDIC-TEC-25-65kW-INSULATION-BOX-HQ/233481969648?hash=item365c9c1ff0:g:~tIAAOSwSA5eNIvJ

 

Edited September 11, 2020 by nicknorman

[nicknorman]

1 hour ago, dor said:

This is what I have.  A switched supply to the ch pump. Doesn’t get the rads as hot as the heating, but as Tony says, enough to take the chill off.

 And all the plumbing is already in place.

Trouble is, if you forget to turn off the pump, your hot water goes cold.

[Bod]

This is what we have done.

Plate heat exchanger in the return from calorifier.

Pipes from plate exchanger to radiators on the gas boiler circuit.  These new pipes have an electric heat proof pump,( taken from the cooling system of a modern car)

The engine water pump does very little extra work, the new electric pump moves the radiator circuit water.

The engine water pump is not powerful enough to pump the central heating system, hence the extra electrical pump.

System works well, if the engine is allowed to warm up, and the calorifier is given time to heat up, then the rads do get very hot, even at canal speeds.

Suitable electric switches, and water isolation valves were fitted.

Best modification we've done on the boat.  If you have radiators fitted, then heating them from the engine is worth doing.

 

Bod.

 

 

[ditchcrawler]

2 hours ago, Tracy D'arth said:

How can you ensure that the engine is topped up when you can't take the cap off without emptying the heating system?

 

 I think using a plate heat exchanger and keeping the systems separate is far better and safer than a solid fuel boiler with no thermostat control running on a pumped sealed system.

Fully agree

 

[dor]

1 hour ago, nicknorman said:

Trouble is, if you forget to turn off the pump, your hot water goes cold.

Which is why there is also a led light so I know the pump is on ...

[MrsM]

Thank you for so many replies to this topic. You really are an amazing bunch and I am so grateful for all the help and advice that this forum continues to provide. You are wonderful. 

[MrsM]

5 hours ago, Alan de Enfield said:

Your wish is my command - and in view of the current situation, a little help with C19 -  Just for you ....................................

 

 

 

 

 

 

 

 

Fantastic. Used up our last tuit converting the beeping Tecma electric flush toilet so it no longer floods our bathroom. 1st button now dispenses water for as long as it is pressed and 2nd button drains the bowl and switches on the macerator. Simples. Why they couldn't have built it like that in the first place is beyond me! Ps face mask is improvement on the Hannibal Lector style one I've been wearing this week! ?

5 hours ago, Alan de Enfield said:

 

 

Edited September 11, 2020 by MrsM
Help! My stoopid reply has gone mad and replicated itself. Please can I delete it?

[Detling]

Have similar plate heat exchanger seperate pump etc, great but the only problem I have found is when you cruise for an hour or so then reach a lock flight or a huge lock queue, after about an 40 odd minutes, on tickover, the engine temp falls. Because the thermostat opens at 75 (I think) but doesn't close until well below that. I have seen the temp drop below 70 before I have spotted, and then turned the pump off so there is no water flow through the rads and heat eaxchanger, temperature then climbs but very slowly as still on tickover.

[TheBiscuits]

1 hour ago, Detling said:

Have similar plate heat exchanger seperate pump etc, great but the only problem I have found is when you cruise for an hour or so then reach a lock flight or a huge lock queue, after about an 40 odd minutes, on tickover, the engine temp falls. Because the thermostat opens at 75 (I think) but doesn't close until well below that. I have seen the temp drop below 70 before I have spotted, and then turned the pump off so there is no water flow through the rads and heat eaxchanger, temperature then climbs but very slowly as still on tickover.

 

Replace your thermostat with a working one!

[johnmck]

Ours works fine.

It's  an Alde heat exchanger. Reverse a couple of valves, switch over the pump from webasto to engine and voila,  hot radiators from the engine.

But...

We don't  use it as much as we should!

[cuthound]

Late to the party as usual.

 

When I collected my second hand boat from the previous owner, the last work it had had done on it was to install a replacement calorifier.

 

On the journey back home, I noticed the radiators were getting hot, but due to the bright June sunlight I couldn't see if the Webasto boiler was on or not, so I turned the radiators off.

 

That night I found the Webasto was switched off. I checked the plumbing, and found whoever had installed the replacement calorifier had plumbed the engine and boiler coils in series, so the engine coolant was being circulated through the Webasto and radiator circuit.

 

As I didn't have any facilities to catch the coolant, I left it as it was for the 3 day journey home, before changing the calorifier pipework so that the engine fed one coil and the boiler the other. I was worried that the engine water pump wouldn't cope with the additional resistance of the central heating circuit but it showed no ill effects. 

 

I have since installed a seperate dc circulating pump to the central heating circuit, which lets me use the calorifier as a crude heat exchanger. When switched on with the engine running it warms the radiators but doesn't  get them really hot. It is sufficient to take the chill off the boat in cool spring and autumn cruising, but not enough in winter. However we have the stove on then to heat the boat.

 

 

[Sea Dog]

1 hour ago, cuthound said:

 

I have since installed a seperate dc circulating pump to the central heating circuit, which lets me use the calorifier as a crude heat exchanger. When switched on with the engine running it warms the radiators but doesn't  get them really hot. It is sufficient to take the chill off the boat in cool spring and autumn cruising, but not enough in winter. However we have the stove on then to heat the boat.

In other words, it's not a particularly effective modification for most of the year and the times where it takes the chill off in cool spring and autumn cruising could perhaps be better covered by a burst on the Webasto which doesn't compromise your hot water storage?

 

It sounds good as a concept, and I'm all for salvaging the otherwise wasted heat, but when there's already a purpose built central heating boiler and a solid fuel stove, it loses out to the law of diminishing returns, doesn't it?

[cuthound]

8 hours ago, Sea Dog said:

In other words, it's not a particularly effective modification for most of the year and the times where it takes the chill off in cool spring and autumn cruising could perhaps be better covered by a burst on the Webasto which doesn't compromise your hot water storage?

 

It sounds good as a concept, and I'm all for salvaging the otherwise wasted heat, but when there's already a purpose built central heating boiler and a solid fuel stove, it loses out to the law of diminishing returns, doesn't it?

 

Yes completely agree. If I were doing it again I would fit a heat exchanger.

 

It is quite low on my "to do" Iist though. 

[Sea Dog]

1 hour ago, cuthound said:

 

Yes completely agree. If I were doing it again I would fit a heat exchanger.

 

It is quite low on my "to do" Iist though. 

Ah, that's interesting. I don't see the argument stacking up in favour of spending on a heat exchanger when a burst of Webasto or a stove is available, depending on the season. You've got experience of this in between solution using the cauliflower though, so that's  fair enough. 

[nb Innisfree]

11 hours ago, cuthound said:

Late to the party as usual.

 

When I collected my second hand boat from the previous owner, the last work it had had done on it was to install a replacement calorifier.

 

On the journey back home, I noticed the radiators were getting hot, but due to the bright June sunlight I couldn't see if the Webasto boiler was on or not, so I turned the radiators off.

 

That night I found the Webasto was switched off. I checked the plumbing, and found whoever had installed the replacement calorifier had plumbed the engine and boiler coils in series, so the engine coolant was being circulated through the Webasto and radiator circuit.

 

As I didn't have any facilities to catch the coolant, I left it as it was for the 3 day journey home, before changing the calorifier pipework so that the engine fed one coil and the boiler the other. I was worried that the engine water pump wouldn't cope with the additional resistance of the central heating circuit but it showed no ill effects. 

 

I have since installed a seperate dc circulating pump to the central heating circuit, which lets me use the calorifier as a crude heat exchanger. When switched on with the engine running it warms the radiators but doesn't  get them really hot. It is sufficient to take the chill off the boat in cool spring and autumn cruising, but not enough in winter. However we have the stove on then to heat the boat.

 

 

On Innisfree I arranged the Mikuni with a tee to divide flow between port and stbd heating runs, port side was further divided via a diverter valve between engine and heating run, by turning valve engine would be in series with heating circuit and preheated, handy in cold weather enabling engine operating temp to be reached in minutes. When engine reached that temp Mikuni would shut down and heating carried on from engine water pump alone, back pressure was enough to prevent engine cooling but not enough to prevent heating circulation. Entire circuit, including engine, ran unpressurised and trouble free for 10 years until I sold Innisfree. 

[Cas446]

3 hours ago, Sea Dog said:

Ah, that's interesting. I don't see the argument stacking up in favour of spending on a heat exchanger when a burst of Webasto or a stove is available, depending on the season. 

Absolutely it's all about personal circumstances. We winter cruise with two young kids, I hate driving with stove smoke in my face, with this system the boat is toasty for them all day long without my intervention, and I get a continual blast of warm air through the hatch. At all other times of the year it just makes keeping towels, coats and kids clothes dry in a busy boat a lot easier as it's 'free' heat whilst on the move. Not for everyone, but for me, a great solution.