Calorifier or not

[wingdiver]

Hi
Anyone know if it is possible to use a domestic water tank instead of a 'marine' calorifier?
Having got one which has a split in it, I wandered in to the swindlery to find a replacement would be around £375-£450 for another 40l one .
Knowing the additional cost of printing the word marine on things , I wondered if there is any way to use a household tank.
We only need fresh water in and out and engine feed in and out (which would be central heating boiler in and out in a house).
The one thing that I guess is different is that many marine ones are set down horizontally but in houses they are vertical. Presumably that changes the coil layout.
Any help would be appreciated.
Cheers
D

 

[tillergirl]

I am neither plumber, engineer or expert but I would have thought there isn't much if any difference. My marine one is perhaps more robust than a domestic hot water tank since it has an outer skin but it can be positioned either vertically or horizontally so position of coil can't affect it. There are things like the pressure release valve - is the pressure on a domestic unit the right value for a marine system? I recall on fitting my tank it had to be below the level of the header tank which it just is - presumably somthing to do with the ability of the pump to get hot water from the heat exchanger round the system. and I have an anode in my which is something to do with it being a steel tank with a copper coil I guess (it does uses anodes!). A domestic unit would be all copper so that shouldn't be a problem. Then you would need some bespoke mountings. These things apart I can't think of any problems. Interesting question.

 

[wingdiver]

Thanks TG.
I just had a word with SureJust who make the SureCal range and it seems that they are pretty much the same inside whether they are horizontal or vertical fitting.
The main difference between marine and domestic is the way the pressure relief works (and vents - into your bilge) and the suggestion that an accumulator may be necessary to help with pressure differences too (assuming the PRV doesn't!).
I think some of the fittings are supposed to be 'marine grade' but I don't generally buy into that.
The only other issue I can think of is if the take off point for hot water out is not near the top (where the water would presumbably be hottest).

 

[tillergirl]

I've added an accumulator this year to stop spurting. The PRV never seemed to vent. Yet to tell if it will work.

I thought domestic tanks took hot water from the top? Thinking on it, my neighbours motor boat has a hot water tank that looks exactly like a domestic one.

 

[MudShipper]

while the theory is good in respect of what and how they work, Domestic HWTs are made from very thin copper - which may be an issue if you like bouncing up and down on the waves or roll a lot as the weight of water will be continuously flexing the tank. This could sooner or later lead to work hardening of the copper and result in a stress fracture.

 

[wingdiver]

while the theory is good in respect of what and how they work, Domestic HWTs are made from very thin copper - which may be an issue if you like bouncing up and down on the waves or roll a lot as the weight of water will be continuously flexing the tank. This could sooner or later lead to work hardening of the copper and result in a stress fracture.

Cheers for that.
I guess the tank needs to be thick enough to withstand the pressure of the heated water plus overengineering on top. PRV seem to go at 4bar which is quite high for domestic mains pressure.
My current one is strapped down in two places and on a rubber matting.
Should be full at all times so it's just a big solid lump unlike the cold tank which is always only part full.
Still investigating......

 

[wingdiver]

An update -
Managed to get a SureCal 40l calorifier from Norfolk Marine (Wroxham).
It was only £275 delivered!! Added an expansion tank with the money I saved.
Took a whole day to drain and flush through engine coolant, drain tank water, disconnect ancient fittings and remove the old tank.
Then found a problem removing the bands that held the old one in.
Sorted this and put the new tank in place but discovered that the fittings on the end were different than before (typical). Tried the swindlery for new adaptors but they only had one when I needed four etc.
Ordered all fittings from Aquafax including extra taps to isolate the calorifier, which arrived next day.
Had to source replacement heater hose in three different internal diameters (of course, why would they all be the same!), rated at a high enough temperature, from Walker Rubber.
All connected, filled fresh water, filled engine cooling side, run engine.
No evidence of connectors from engine coolant to coil on calorifier getting hot. Perceived wisdom from ybw search is air lock(s).
Suggested to run engine with pressure cap off to try and shift it, then 'bleed' the pipes on the calorifier.
Still no good.
Eventually drain some of the engine coolant and disconnect the flow and return off the engine so the coil can be filled by gravity before refitting and running.
Success!!
All that's left to do now is test the electric immersion heater.
NOTE TO SELF..... if there is ever a next time, fill the coil on the calorifier before fitting to avoid the ache of trying to get the air out after it's bolted down in a locker!!!
Also, isn't it weird how things have metric and imperial on the same fitting? Like a 3/8 BSP thread one end and a 15mm hose tail the other.....