Water Calorifier for cabin heating idea?

[Sierra2]

Happy Xmas eve all!

 

I was wondering if any of you would be Santa's could bring me an early present/answer with an idea I've started thinking about for heating?

 

I have a 55lt Calorifier that I will be refitting to my 31ft GRP Motor Cruiser. It is powered by an AC heating element when on shore power or the Starboard engines heat exchanger when cruising.

 

Is there any reason I couldn't add a AC pump and use the heated water to heat small 'skirting board' type radiators throughout the boat? This would be one method of heating the boat, not the only one. If it works I'd be happy to spend the money saved on a Diesel boiler elsewhere on secondary heating.

 

Some problems I could potentially see:

 

1) With the system pressurized I could imagine problems with it tripping the hot water pressure switch and activating the DC hot water pump?.

 

2) I presume the AC heating element I have has a thermostat (so it's not constantly on). How much heat loss within the water temperature do you get through radiators? I understand heating through AC is generally inefficient but as I was planning to leave the calorifer on (while on shore power) am I looking at a higher bill? Is this a viable alternative to Gas bottles and expensive boilers?

 

4) Control. I could always put the AC pump on a automatic timer but in terms of regulating the temperature while the system is on, is it just Thermostatic Valves(?) on the radiators and will they do the job?

 

5) On a side note, the insulation around the Calorifer is tatty and falling off in parts. Is there any reason I couldn't cut it all off and have the Spray Foam contractor spray over it once it has been refitted and plumbed in, in place? I would mask up all the connections for inspection and future works. Does the temperature get beyond the working temperature of the closed cell spray foam?

 

Thanks in advance for any help

[David Mack]

The stored heat in the calorifier won't heat the radiators for long if there is no immersion/engine heat going in.

 

If you leave the immersion heater connected to shore power, then the whole system has just become an electric heater. A fan heater or oil filled radiator would be a quicker and easier way to do this.

[Bloomsberry]

I think the heating element in a standard calorifier is only rated at 1kw anyway so I wouldn't have thought this sufficient to supply the heating requirements on a boat.

[koukouvagia]

Sometimes I forget to switch off the circulation pump at night. With the diesel fire also turned off the heat from the calorifier is therefore distributed through the radiators. Within a very short while the radiators are stone cold and there is no hot water in the calorifier.

I very much doubt whether your idea would be very practical since, as Bloomsberry points out, a 1kw element is hardly going to be sufficient for supplying both hot water and heating.

[blackrose]

Yes, if you have shore power get yourself an oil filed electric radiator (with thermostatic control). Plenty of different ones available at Argos. You probably want 2kW+. It will be a lot quicker than waiting for an entire calorifier full of water to heat up before you get any heat into the boat.

 

The oil filled electric rad won't help when you're off shore power so perhaps your idea would work there, but I'd be using a 12v pump, not AC pump.

Edited December 25, 2015 by blackrose

[Iain_S]

(snip)

I have a 55lt Calorifier that I will be refitting to my 31ft GRP Motor Cruiser. It is powered by an AC heating element when on shore power or the Starboard engines heat exchanger when cruising.

(snip)

 

How about running the port engine's primary coolant through a radiator or two?

On a broad beam trip boat I drive, there are three radiators which run from the generator coolant, with no extra pump. Originally, there were six radiators in the circuit, but three were removed as they didn't get hot enough. It works OK on three domestic size radiators.

[dor]

Won't do much if the engine is not running. However I get the rads quite hot if I leave rad & HW circuits open with the CH pump running but not actually running the CH boiler. Useful for putting a bit of warmth into the cabin for free when out cruising in cold weather.

[blackrose]

 

How about running the port engine's primary coolant through a radiator or two?

On a broad beam trip boat I drive, there are three radiators which run from the generator coolant, with no extra pump. Originally, there were six radiators in the circuit, but three were removed as they didn't get hot enough. It works OK on three domestic size radiators.

I was always led to believe that the engine's water pump was more of a stirrer and would be too weak to pump water through an entire central heating system without an additional pump?

Edited December 25, 2015 by blackrose

[Iain_S]

All 3 radiators get hot. Boat is 60ft, with generator under stern deck, so around 40ft pipe run. Seems to work

Won't do much if the engine is not running. However I get the rads quite hot if I leave rad & HW circuits open with the CH pump running but not actually running the CH boiler. Useful for putting a bit of warmth into the cabin for free when out cruising in cold weather.

 

This worked for us in Copperkins as well, although I'd describe the radiators as "warm", rather than "quite hot".

[nb Innisfree]

I was always led to believe that the engine's water pump was more of a stirrer and would be too weak to pump water through an entire central heating system without an additional pump?[/quote

I was always led to believe that the engine's water pump was more of a stirrer and would be too weak to pump water through an entire central heating system without an additional pump?

 

Innisfree has 4 domestic rads +1 calorifier running down the port side (30'run) and 2 domestic rads +1 cal on the starboard side (38'run) total 7kw. All capable of reaching 80c on engine pump. Engine is LPWS4 with unpressurised coolant direct to rads.

[cuthound]

I was always led to believe that the engine's water pump was more of a stirrer and would be too weak to pump water through an entire central heating system without an additional pump?

When I bought DQ (60 foot narrowboat with three radistors and a heated towel rail) the calorifier had just been replaced. The two calorifier coils had been connected in series so that both the Beta 43 engine and Webasto central heating fed the calorifier and the radiators. The rads heated up really well, especially on our inaugural trip in June and the engine showed no signs of over cooling. However I had it replumbed so that the Webasto and engine were on separate coils. At the same time I added an auxiliary pump so that I could use the calorifier as a heat exchanger and heat the rads indirectly from the engine. It works OK, but the rads only get warm, not hot. Good enough to take the chill off the boat, but not to hear it. At some point in the future I will fit a proper heat exchanger.

[Sierra2]

Thanks for all the replies guys (sorry been busy seeing the new year in )

 

Good feedback on what I thought was an ambitious idea. I did intend to use the Port engine to power a Matrix heater to demist the windows in the wheelhouse, but quite like the idea of an additional independent radiator for cold weather cruising.

 

Any thoughts on Point 5...?

 

"the insulation around the Calorifer is old, tatty and falling off in parts. Is there any reason I couldn't cut it all off and have the Spray Foam contractor spray over it once it has been refitted and plumbed in? I would mask up all the connections for inspection and future works"

 

Thanks again