Hot Water Calorifier

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Dazzajohm

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Good Afternoon,

I've recently had a hot water calorifier installed on my boat as per the link below;

https://www.asap-supplies.com/domes...ers/supa-hotpot-single-coil-calorifier-520115

I tasked a local company to do this for me, however it wasn't until afterwards when they left me all the paperwork which I had a good look through I realised the instructions talk about installation of an expansion tank.

Looking at what's been installed, there is no expansion tank (not sure I'd have room for one anyway) and there is only a hose coming off the pressure release valve outlet in to the bilge.

Is this an acceptable setup?

Thanks in advance.
 
Dazzajohm said:
Good Afternoon,

I've recently had a hot water calorifier installed on my boat as per the link below;

https://www.asap-supplies.com/domes...ers/supa-hotpot-single-coil-calorifier-520115

I tasked a local company to do this for me, however it wasn't until afterwards when they left me all the paperwork which I had a good look through I realised the instructions talk about installation of an expansion tank.

Looking at what's been installed, there is no expansion tank (not sure I'd have room for one anyway) and there is only a hose coming off the pressure release valve outlet in to the bilge.

Is this an acceptable setup?

Thanks in advance.
Click to expand...

My Sadler34 was built with a calorifier but without an accumulator and with the prv venting into the bilge, although it never has. It worked perfectly well for more than ten years until I fitted an accumulator immediately downstream of the domestic water pump. This was to quieten the annoyingly persistent sound of pumping when the taps were opened, not to overcome any calorifier problems.
 
vyv_cox said:
I fitted an accumulator immediately downstream of the domestic water pump. This was to quieten the annoyingly persistent sound of pumping when the taps were opened, not to overcome any calorifier problems.
Click to expand...
Sorry to hijack a thread so early but I found this interesting - My system has an accumulator but the pump comes on when I run the water, casting my mind back, I don't think it did when I got the boat 17 yrs back. Does this indicate a pressure leak?
 
LadyInBed said:
Sorry to hijack a thread so early but I found this interesting - My system has an accumulator but the pump comes on when I run the water, casting my mind back, I don't think it did when I got the boat 17 yrs back. Does this indicate a pressure leak?
Click to expand...

If the pump runs continuously when the tap is turned on the accumulator is not functioning. This is usually because the air in it has leaked out although there are other possibilities. Ideally the pump will only run briefly every few seconds. Try pumping up the accumulator with your bike pump while the tap is running. The period between pump runs will increase, then reduce again as air pressure increases. Let air out slowly until the period between pump runs is maximised.
 
Thanks for that insight.

My system works fine and I can't say I noticed any problems yet although I've only
Tried it once after a run out around Dover Harbour where the engine heated the water. When I turned on the hot tap, hot water came out and the pump came on. A second after turning the hot tap off the pump switched off.
I just wanted to make sure there not going to be a problem with the tank not having the expansion tank
 
Dazzajohm said:
Good Afternoon,

I've recently had a hot water calorifier installed on my boat as per the link below;

https://www.asap-supplies.com/domes...ers/supa-hotpot-single-coil-calorifier-520115

I tasked a local company to do this for me, however it wasn't until afterwards when they left me all the paperwork which I had a good look through I realised the instructions talk about installation of an expansion tank.

Looking at what's been installed, there is no expansion tank (not sure I'd have room for one anyway) and there is only a hose coming off the pressure release valve outlet in to the bilge.

Is this an acceptable setup?

Thanks in advance.
Click to expand...

I suppose you know that its a pressurised system and that the relief valve is the last resort being set above expected normal operating pressure and that water expands when heated and being theoretically incompressible would tend to cause all your fittings downstream to pop off so to speak and the tank to rupture should the water get very hot and the relief valve fail to operate and even then if it did not fail you don't really want to lose some your precious fresh water to the bilges . hence the expansion tank
In practice you may have plastic hoses instead of copper pipes so they have a bit of give so to speak and there also may be some air trapped in the calorifier itself depending on where the outlet is in relation to the top of the calorifier . So you may get away with it .

also it becomes very annoying every time you open a tap to draw off a little water you hear a noisy pump running . . So having a an expansion tank gives you an operating range of pressure with out the pump running all the time
Another thing is the small scale on a boat .
in modern houses with large calorifiers the energy stored in a tank is much higher and the regulations are stringent . If you troll on the internet there is a Youtube video of the damage done by a calorifier exploding

in a previous existence as an apprentice in Weir pumps I once witnessed the explosion of a small pump barrel exploding under hydrotest when the test pump went past the required test pressure as the other apprentices were having a smoke . The steady duh , duh , duh of the hydraulic test pump suddenly increased in speed as the water went HARD and BANG LOTS OF SHRAPNEL FLYING ABOUT . Not much left of the pump
Although its was incompressible water there was some air in the system which did compress thus increasing the stored energy greatly
 
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Great, thanks for the input, and blimey catmandoo is definitely filled with the joys of Spring :).

I've also asked around some of my other boaty friends and it does seem quite common not to have an expansion tank, at least at first and only fitting one at a later date if absolutely required.

I guess I'll just see how it goes over the season and if there are problems have to rethink. Just hope we don't get the issues catmandoo mentions :-/
 
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