Jump to content

Central heating without the diesel heater on ?


La Peniche 11

Featured Posts

I'm having a new boat built and trying to fathom out a way of utilising the hot water in the calorifier (produced from either the engine running or the immersion heater)to warm the radiators, without turning the Webasto diesel heater on.

 

It seems a waste to use the Webasto just to pump the hot water around, when I don't require the water to be heated by the Webasto. In my old boat I had to turn the Eberspacher on to utilise the heat from the calorifier to heat the radiators.

 

Example 1. We're crusing along a canal and the water in the calorifier has been heated by the engine. Is there a simple way of pumping that water around the radiators without involving the Webasto heater ?

 

Example 2. We're in a marina and on shore-power. W've used the immersion heater to heat the water in the calorifier. We don't need the Webasto to heat the water, we just need the hot water in the calorifier pumped around the radiators.

 

I'd appreciate any ideas, and excuse my ignorence if it's a daft question or it's been discussed before.

 

Brian

Link to comment
Share on other sites

In the simplest of ways just turn on the Erbaspacher/Webasto pump. The system will work in reverse, ie taking the heat from the calorifier.

 

There may be issues with the Erbaspacher/Webasto but I will leave that to those that know.;)

 

Did this on a hire boat many years ago (gas boiler) but the radiators were only 'tepid' to touch.

Link to comment
Share on other sites

Well done for thinking about this on your new build, its a good question to ask builders why they dont do it in the first place.

As to the engine heat very simple, use a heat exchanger, see link to the idea being used for an ALDE. The waste heat from the engine water circuit going to the calorifier is extracted by the heat exchanger, and the heat is used in the central heating circuit. In the case of the ALDE you can utilise the central heating pump to circulate water when the engine is on but the heater is not on, (or use the waste heat when the engine is on to provide some heat and the ALDE is on to supplement it and bring the rads up to temp, thus saving gas). I dont know what the Webasto set up is but you will need a pump and switch

When hooked to 240v its the same idea, just needs thinking through. Again the ALDE is set up for this idea as standard as the electric heater is built into the unit as standard when on land line

 

http://www.ashbyboats.com/MeashAlde.htm

 

Charles

  • Greenie 1
Link to comment
Share on other sites

We've had threads before about putting a heat exchanger and pump between the engine, calorifier and rads (which would only heat the rads while the engine was running), but I hadn't thought about putting the heat exchanger between the calorifier and rads so that the rads could be heated indirectly from the immersion heater while the boat was on shore power.

 

But then if you are on shore power wouldn't it be simpler and probably more energy efficient to buy an oil-filled electric rad with thermostatic control?

Edited by blackrose
Link to comment
Share on other sites

I have a Bowman type tubular heat exchanger built in to the CH circuit on the boiler output pipe, so that hottest water goes first round

system rather than heating up boiler. HE flows should be opposite each other for max heat transfer.

 

Bowman HE

 

Engine calorifier connections supply hot water to HE. I have a delay on relay for the CH pump switched by engine ignition switch, so CH pumps starts 15 mins after engine, giving time to warm up. Result is 14 radiators and 2 calorifiers that are brilliantly hot while motoring.

Link to comment
Share on other sites

Some (most?) calorifier circuits take engine hot water from the same tappings as would be used for the heater in a car - ie before the thermostat. If too much heat is taken out of the system compared to how much heat the engine is generating, the result is too cool an engine working temperature which might be bad for the engine long term. With a calorifier, the engine will run a bit cool for a short while until the water in the calorifier tank is up to temperature, then the engine will be running at the correct thermostat-controlled temperature for the rest of the day.

So it would be better to take the heat from after the thermostat - ie via a heat exchanger from the skin tank circuit. It may take a little longer for the radiators to heat up, but there would be no risk of long term over-cool running. I bought a cheap plate heat exchanger from here which seems good value, though I have yet to install it.

 

It would not work for when you are on shore power, but perhaps it would be easier to use an electric fan heater or oil filled radiator etc for that.

 

Nick

Link to comment
Share on other sites

I bought a cheap plate heat exchanger from here which seems good value, though I have yet to install it.

 

It would not work for when you are on shore power, but perhaps it would be easier to use an electric fan heater or oil filled radiator etc for that.

 

Nick

Will you been running your cooling through the larger tappings and do you think it will cause problems restricting the flow?

Link to comment
Share on other sites

We have a Mikuni MX60, unfortunately it's 24v so we are unable to run it's water pump separately but 12v model can do this so probably the same with Webasto. You could plumb in a separate inline CH pump instead which can be switched off when Webasto is operating. If we wait until heated water from engine is above 70C Mikuni will start up with water pump only. Running calorifier heat exchanger in reverse will result in water and therefore radiators gradually cooling down unless DHW can be heated fast enough to keep up.

Link to comment
Share on other sites

Will you been running your cooling through the larger tappings and do you think it will cause problems restricting the flow?

 

The piping to the skin tank is 28mm, so the exchanger would be too small to take the full flow without undue restriction. So I will be using the larger tappings but also bypassing the exchanger with an adjustable (28mm) gate valve - ie valve wide open, no significant differential pressure to cause much flow through the exchanger, valve closed down a bit, some water diverted through the exchanger but some able to flow through the valve to preserve the overall flow rate. Hopefully that should be OK!

 

Nick

Link to comment
Share on other sites

I have arranged heat from the engine as a retrofit, much as has been described. The CH has an Eberspacher boiler; a plate exchanger (about £25 from ebay) has been introduced into the circuit, along with a centrifugal (Bolin) pump (rather more £££). The supply is taken from the calorifier circuit; thee were several reasons why I took this route - it is the most straightforward for plumbing as both circuits go to the twin coil calorifier, where I had room for the kit. Also, I did not wish to risk overheating the engine by restricting the flow to the skin tank - the plate exchanger has 3/4 bsp fittings. I appreciate that a bypass could be arranged, but in my case the Barrus engine has two thermostats so there is no risk of over cooling the engine. Even if there was a risk of overcooling, I would prefer that to overheating!

 

Obviously the engine needs to be hot for it to work, but it performs very well.

 

Ian

Link to comment
Share on other sites

If its a twin coil cauliflower could you not use the cauliflower as the heat exchanger. Use one coil to put the heat in either from the engine or Webasto and the other to take it out to the rads? The immersion could also put the heat in. With the rads connected to the 2nd coil & a 12v circulation pump it would surely work. Perhaps not very efficient using the Webasto but the engine heat would be free & the immersion well????

Would seem to be much simpler. (I like simple!!)

 

Steve

Link to comment
Share on other sites

If its a twin coil cauliflower could you not use the cauliflower as the heat exchanger. Use one coil to put the heat in either from the engine or Webasto and the other to take it out to the rads? The immersion could also put the heat in. With the rads connected to the 2nd coil & a 12v circulation pump it would surely work. Perhaps not very efficient using the Webasto but the engine heat would be free & the immersion well????

Would seem to be much simpler. (I like simple!!)

 

Steve

Twin coil cauliflower :clapping::clapping::clapping:

Link to comment
Share on other sites

If its a twin coil cauliflower could you not use the cauliflower as the heat exchanger. Use one coil to put the heat in either from the engine or Webasto and the other to take it out to the rads? The immersion could also put the heat in. With the rads connected to the 2nd coil & a 12v circulation pump it would surely work. Perhaps not very efficient using the Webasto but the engine heat would be free & the immersion well????

Would seem to be much simpler. (I like simple!!)

 

Steve

 

 

Hi

 

I used this method with a 12V Webasto pump. It has been very succesful

The CH wont get very hot as the engine temperature rarely reaches 80 degrees, but any free heat is good heat.

 

Alex

Link to comment
Share on other sites

Hi

 

I used this method with a 12V Webasto pump. It has been very succesful

The CH wont get very hot as the engine temperature rarely reaches 80 degrees, but any free heat is good heat.

 

Alex

Hi Alex,

very interested in this, would it be possible to tell me how you did it ?.

Did you use the integral Webasco pump or are you using a seperate pump.

I,m assuming adding a heat exchanger is unneccesary

John

Link to comment
Share on other sites

Hi

 

I used this method with a 12V Webasto pump. It has been very succesful

The CH wont get very hot as the engine temperature rarely reaches 80 degrees, but any free heat is good heat.

 

Alex

 

Hi Alex

 

Our Mikuni shuts down at 70C and carries on with water pump only, I feel sure Webasto is similar so engine at between 70c and 80C should be ok for CH.

 

Chris

Link to comment
Share on other sites

Hi Alex

 

Our Mikuni shuts down at 70C and carries on with water pump only, I feel sure Webasto is similar so engine at between 70c and 80C should be ok for CH.

 

Chris

 

 

Hi Chris

 

I'm suprised the Mikuni only reaches 70C, when my Eberspacher is on, the radiators get much hotter, although I like the fact the CH water is already warm.

I have no idea how hot the Ebespacher gets but my engine only really gets up to 70C +

 

You convinced me to have a look up the Eberspacher specs.

I seems it reaches 80C and then goes onto low setting up to 85C then stops feeding the fuel in, It stays like this until the Ch water drops to 70C.

 

Alex

Link to comment
Share on other sites

Hi Alex,

very interested in this, would it be possible to tell me how you did it ?.

Did you use the integral Webasco pump or are you using a seperate pump.

I,m assuming adding a heat exchanger is unneccesary

John

 

 

Hi

 

Water from the boiler is fed to the top coil of the calorifier and 'Tees' off to the CH.

I simply 'teed' into the return pipe of the top coil off the twin coil calorifier and into the feed pipe to the CH. I thought the restriction of the boiler pump would stop water back flowing around the boiler and it seems to.

I fitted a separate switch for the pump. Mainly because I was worried that it would continue to take all the hot water from the calorifier when we stopped the engine and needed a shower etc and because you dont need it in summer.

I have left in on along with the boiler at times, but I'm not sure there is any benefit to the circulation through the CH, there are certainly no ill effects.

I bought a replacement 12v circulating pump (Webasto or Eberspacher) from EBay, although I cant see one for sale at the moment.

 

Alex

Link to comment
Share on other sites

Hi Chris

 

I'm suprised the Mikuni only reaches 70C, when my Eberspacher is on, the radiators get much hotter, although I like the fact the CH water is already warm.

I have no idea how hot the Ebespacher gets but my engine only really gets up to 70C +

 

You convinced me to have a look up the Eberspacher specs.

I seems it reaches 80C and then goes onto low setting up to 85C then stops feeding the fuel in, It stays like this until the Ch water drops to 70C.

 

Alex

 

Mikuni is similar but 5c lower, more like a domestic boiler I think, rads are plenty hot.

Link to comment
Share on other sites

I've used the 'twin coil cauliflower as heat exchanger' idea..it was an unintended consequence of refitting the central heating. I've got a 70' nb with a bolin to pump coolant up and down the boat through mostly 15mm pipes into rads. Don't get a great deal of heat when pottering along the canal - a nice gentle heat though. On the Thames though we used to get the radiators almost too hot too touch, especially motoring upstream if there was a bit of a current.

 

Don't forget that if you don't turn the pump off when you stop the engine, it will keep pumping round and round until all the water in the cauliflower is cold. :-(

Link to comment
Share on other sites

If its a twin coil cauliflower could you not use the cauliflower as the heat exchanger. Use one coil to put the heat in either from the engine or Webasto and the other to take it out to the rads? The immersion could also put the heat in. With the rads connected to the 2nd coil & a 12v circulation pump it would surely work. Perhaps not very efficient using the Webasto but the engine heat would be free & the immersion well????

Would seem to be much simpler. (I like simple!!)

 

Steve

 

I tried it too but the rads just got warm rather than hot. The calorifier is not a great heat exchanger if used in reverse (i.e. hot water in the tank heating water moving through the coils) - at least not if you want to pump that heat around rads which emit the heat quickly.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.