central heating

[colin loach]

what is the best way to heat the tap water and the radiators from the engine at the same time. Colin.

[denboy]

Fit a clarifier

[nb Innisfree]

what is the best way to heat the tap water and the radiators from the engine at the same time. Colin.

 

We have connected CH, calorifiers and engine, the main consideration is safety, engine coolant can reach scald temp. and could be a problem with children touching radiators also we depressurised engine coolant for the same reasons. It all has worked well for 4 years the only issue has been engine warm up in the winter which we have addressed by preheating with a Mikuni. If you don't preheat then I would fit a valve between engine and CH, wait until engine (and therefore calorifier) has reached operating temp then open valve to CH

[Robbo]

what is the best way to heat the tap water and the radiators from the engine at the same time. Colin.

 

Prob best if you say how your currently setup.

 

We have connected CH, calorifiers and engine, the main consideration is safety, engine coolant can reach scald temp. and could be a problem with children touching radiators also we depressurised engine coolant for the same reasons.

 

Use thermostats on the radiators so you can set the temperature per radiator, and a thermostatic mixer for the hotwater so you can set the temperature here as well.

[colin loach]

at the moment I have a gas water heater, but I would like to connect the calorifier in line to get heat from the engine. I also would like to fit two radiators to the calorifier but I was told the rads wont get very hot. after reading your reply it seems that the rads may get to hot. I was thinking of fitting a twin coil calorifier about 40 litres but not sure this is the best way to get the heat from the engine.

[dor]

The calorifier is the equivalent of the hot water tap in a domestic heating system. A twin-coil tank wiull hacve two coils inside. One is connected to the engine cooling system (you do have a water cooled engine with a skin tank don't you?). This is very straightforward, although the actual connection points vary between engines - they need to be to the right side of the thermostat. The other coil is connected to your central heatin system. A boiler, either diesel or gas, is used, and the circuit will go round the rads with a Teed-off link to the other calorifier coil.

 

This way the engine will het the water quite quickly, but can be topped up by the boiler if required. Various refinements can be added. I would go for a 60 litre calorifier if you have the room.

 

You can run the pump only, and use the heat exchanger to heat the rads from the hot water in the calorifier. Alternatively connect a couple of rads in series with the calorifier coil after the calorifier. They will get reasonably hot, very hot after the water has got up to temperature. Make sure the plumbing can deal with the high temperature (up to 80deg instead of normal 60 degrees) and can handle the pressure (shouldn't be a problem as the engine doesn't pressurise that much).

Edited July 23, 2009 by dor

[mikevye]

what is the best way to heat the tap water and the radiators from the engine at the same time. Colin.

 

The engine coolant is usually pressurised to 13psi which can be verified by the rating on the cap on the header tank. I wouldn't have thought that modern radiators are designed to run anywhere near this pressure so unless you run twin coils and a seperate pump the ideas a no no.

[nb Innisfree]

The engine coolant is usually pressurised to 13psi which can be verified by the rating on the cap on the header tank. I wouldn't have thought that modern radiators are designed to run anywhere near this pressure so unless you run twin coils and a seperate pump the ideas a no no.

[/quote

 

13 psi equates to about 30' head of water which is not an unusual height for a header tank in a domestic setting so rads will be well within their design range. The prob is if a leak develops at any pressure combined with high temp. I would advise either box in rads and piping or run system unpressurised. We run CH (5 rads) down both sides of boat + 2 single coil calorifiers. Engine runs unpressurised with no ill effects and engine pump circulates everything ok. As I said earlier the only issue is engine warmup time in the winter. After a 3 hour cruise in winter we have 2 x 50lts of piping hot water and the boat is lovely and warm.

Edited July 23, 2009 by nb Innisfree

[nb Innisfree]

Prob best if you say how your currently setup.

 

 

 

Use thermostats on the radiators so you can set the temperature per radiator, and a thermostatic mixer for the hotwater so you can set the temperature here as well.

 

I think TRVs control air and not water temp? if so rad water will still reach high temp.

[colin loach]

Many thanks to everyone you have all been a great hjelp.

[david and julie]

You could also use cabin heaters like these from VWP.

http://www.vehicle-wiring-products.eu/VWP-...ries/aircon.php

http://www.vehicle-wiring-products.eu/VWP-...photo/60210.jpg

Quite easy to fit and no complications which calorifiers or central heating, you just connect them in the calorifier return. I have one on my boat and they work much like a car heater.

[WotEver]

You could also use cabin heaters like these from VWP.

http://www.vehicle-wiring-products.eu/VWP-...ries/aircon.php

http://www.vehicle-wiring-products.eu/VWP-...photo/60210.jpg

Quite easy to fit and no complications which calorifiers or central heating, you just connect them in the calorifier return. I have one on my boat and they work much like a car heater.

 

Neat idea

[mikevye]

13 psi equates to about 30' head of water which is not an unusual height for a header tank in a domestic setting so rads will be well within their design range. The prob is if a leak develops at any pressure combined with high temp. I would advise either box in rads and piping or run system unpressurised. We run CH (5 rads) down both sides of boat + 2 single coil calorifiers. Engine runs unpressurised with no ill effects and engine pump circulates everything ok. As I said earlier the only issue is engine warmup time in the winter. After a 3 hour cruise in winter we have 2 x 50lts of piping hot water and the boat is lovely and warm.

 

I stand corrected on the pressure issue apparently anywhere between 0.5/1 bar is the norm. To say the engine runs depressurized with no ill effects is incorrect. To run your engine at any temperature below working temperature is highly detrimental to the wear rate of the unit and to fuel consumption. The engine will never reach optimum temperature unpresssurised and in the case of most modern engines aeration at the pump will occur maybe thats why your water gets hot. Worst case scenario for your recommendation is the system leaks, engine runs dry seizes hey presto new engine, some saving!

[KenK]

In addition to thinking about heating the rads, make sure that you include a bypass to avoid heating them in hot weather. You don't need hot radiators when it is 30+ outside, it does happen even in this country. Also if you use a twin coil calorifier consider this, nice warm day don't bother heating radiators, cools down in the evening turn on fire etc to heat rads, cold water flows through calorifier coil for a while before the fire gets it up to temperature, next morning lukewarm shower. Finally if you fit a bypass make sure you also fit an overpressure vent on the bypassed coil, as the water in the tank heats up the pressure rises in the coil and it needs releasing.

 

Ken

[colin loach]

at the moment I have a gas water heater, but I would like to connect the calorifier in line to get heat from the engine. I also would like to fit two radiators to the calorifier but I was told the rads wont get very hot. after reading your reply it seems that the rads may get to hot. I was thinking of fitting a twin coil calorifier about 40 litres but not sure this is the best way to get the heat from the engine.

[mikevye]

I was thinking of fitting a twin coil calorifier about 40 litres but not sure this is the best way to get the heat from the engine.

 

it is.

[colin loach]

I don't understand why the pressure in the engine system will effect the rads.I was going to connect the second coil to the rads making it a completely sealed system with its own pump and a pressure vessel. I would only turn the pump on when I want the rads to get hot. the hot water will work off the first coil also with a pressure a .vessel. I also thought the engine thermostat would not open until the engine reaches its correct temperature.

[nb Innisfree]

I don't understand why the pressure in the engine system will effect the rads.I was going to connect the second coil to the rads making it a completely sealed system with its own pump and a pressure vessel. I would only turn the pump on when I want the rads to get hot. the hot water will work off the first coil also with a pressure a .vessel. I also thought the engine thermostat would not open until the engine reaches its correct temperature.

 

Engine pressure will only affect rads if engine and rads share the same coolant, in your example it won't be an issue

 

I stand corrected on the pressure issue apparently anywhere between 0.5/1 bar is the norm. To say the engine runs depressurized with no ill effects is incorrect. To run your engine at any temperature below working temperature is highly detrimental to the wear rate of the unit and to fuel consumption. The engine will never reach optimum temperature unpresssurised and in the case of most modern engines aeration at the pump will occur maybe thats why your water gets hot. Worst case scenario for your recommendation is the system leaks, engine runs dry seizes hey presto new engine, some saving!

 

Point taken about unpressurised engine coolant, I was just commenting on my setup which has run for 4 years, engine temp and fuel economy are identical whether I run it pressurised or not (I can switch between both if req.) if pressurised, engine reverts to normal closed circuit and reaches operating temp quicker tho in the summer it is not much slower, helped of course by rads being turned off in summer

Edited July 24, 2009 by nb Innisfree

[KenK]

I don't understand why the pressure in the engine system will effect the rads.I was going to connect the second coil to the rads making it a completely sealed system with its own pump and a pressure vessel. I would only turn the pump on when I want the rads to get hot. the hot water will work off the first coil also with a pressure a .vessel. I also thought the engine thermostat would not open until the engine reaches its correct temperature.

 

In addition won't there be some other form of heating connected to the radiators as running engines when you are not cruising just to heat radiators is very inefficent.

 

Ken

[nb Innisfree]

I don't understand why the pressure in the engine system will effect the rads.I was going to connect the second coil to the rads making it a completely sealed system with its own pump and a pressure vessel. I would only turn the pump on when I want the rads to get hot. the hot water will work off the first coil also with a pressure a .vessel. I also thought the engine thermostat would not open until the engine reaches its correct temperature.

 

Problem is most engines have calorifier takeoff before t/stat so will slow engine warmup. Don't turn CH pump on before engine reaches operating temp

[colin loach]

point taken about turning on rads before the engine is warm, I have a solid fuel fire I use to keep the boat warm, but when cruising the smoke sometimes blows into your face, so I will only use the rads when cruising or when charging my batteries