I need a new Calorifer

[Irish Rover]

Paul - I may have been referring to an accumulator tank (http://www.surejust.co.uk/accumulator-tanks) which (I believe - not being aboard!) is on the cold side, and the only tank in my simple system.

I would however assure the OP about my recollection of my experience with the calorifier connections - I am absolutely certain that I mistook the 'nipples' on the Surecal for hose barbs, and Surecal put me right!

Thanks. What you’ve suggested looks just what I need for the connection. The expansion tank needs to be on the hot side according to the instructions but I’m questioning if it’s really necessary as the old set up was almost identical and didn’t have one.

 

[Hydrozoan]

Thanks. What you’ve suggested looks just what I need for the connection. The expansion tank needs to be on the hot side according to the instructions but I’m questioning if it’s really necessary as the old set up was almost identical and didn’t have one.

Good - and apologies to you and Paul for my expansion/accumulator tank confusion.

 

[PaulRainbow]

Paul - I may have been referring to an accumulator tank (http://www.surejust.co.uk/accumulator-tanks) which (I believe - not being aboard!) is on the cold side, and the only tank in my simple system.

I would however assure the OP about my recollection of my experience with the calorifier connections - I am absolutely certain that I mistook the 'nipples' on the Surecal for hose barbs, and Surecal put me right!

I think you were, it is indeed the accumulator that goes on the cold side, just after the pump. You are correct about the hosetails they are apparently designed for Hep2O.

 

[Irish Rover]

So can I skip the expansion tank?

 

[KAL]

So can I skip the expansion tank?

I fitted a surecal and have no expansion vessel. All fine and has been since fitting. A really good unit.

 

[Hydrozoan]

I think you were, it is indeed the accumulator that goes on the cold side, just after the pump. You are correct about the hosetails they are apparently designed for Hep2O.

Yes, I’ve apologised for my confusion – my excuse is that all the Surecal tanks are shown coloured red, though on the installation diagram they show the expansion as red and the accumulator as blue. The tails should fit any of the plastic plumbing system; as I said, I used JG Speedfit - with double O-ringed pipe inserts, and have never had a joint leak on the calorifier or anywhere else.

So can I skip the expansion tank?

I see that Surecal say one is '...an essential feature on any hot water system' (http://www.surejust.co.uk/expansion-tanks), but I have just one tank and I believe it is an accumulator on the cold side . I'll check for sure when I next get to the boat in a week or two, but I guess that may be too late for you.

ISTR that, after reading various threads here, I decided to put in an accumulator despite its being possibly superfluous with the ParMax pump, but to dispense with an expansion tank. The PRV/drain line is routed to the engine bilge, and I have never noticed any blowout. The pump operates very occasionally when no water has been drawn - but not noticeably more often than when I had installed only the cold circuit.

 

[Irish Rover]

Thanks again for all the replies and advice. YBW Forum and its generous contributors are an invaluable resource for Johnny-come-lately amateur DIY boat owners like myself.

 

[vyv_cox]

If there is a non-return valve on the cold water inlet to the calorifier any expansion of the water due to heating cannot expand backwards to the accumulator that is in the cold supply near the pump. In this case a second one is needed in the hot outlet from the calorifier.

 

[Irish Rover]

If there is a non-return valve on the cold water inlet to the calorifier any expansion of the water due to heating cannot expand backwards to the accumulator that is in the cold supply near the pump. In this case a second one is needed in the hot outlet from the calorifier.

I guess that makes sense and the Surecal has a NR on the cold supply. There’s a pressure release valve with a drain to the bilge so I think I’ll rely on that for now and see how I go. If necessary I’ll fit the expansion tank later.

 

[Hydrozoan]

Hmm. I’m beginning to wonder now, as I usually do things ‘by the book’, if I did use an expansion tank on the hot side and relied on the pump not needing an accumulator. Best I check and in the meantime you ignore my observations on that.

 

[Spirit (of Glenans)]

Thanks again to all for their help.
It could well be argued that Northern Ireland is the only part of the U.K. which isn’t an island. It’s only a bit of an island - add smileys as you see fit.

Get a Parcel Motel account and get stuff sent to NI at UK rates, they will then forward it to one of their self service sites in ROI for a small fee.
Get an Addresspal account and it will be sent to a Hampshire address at UK rates then forwarded to an An Post office of your choice for an even smaller fee. An item like a calorifier may well be oversize and attract an extra charge, unless it's packed very compactly.

 

[Irish Rover]

Would I be correct in assuming that an expansion tank and an accumulator tank are one and the same thing?

 

[vyv_cox]

Would I be correct in assuming that an expansion tank and an accumulator tank are one and the same thing?

Yes. There are slight design differences, with diaphragm, without diaphragm, with and without schrader valve. Each has slightly different installation requirements but all do the same job, reliant on the higher compressibility of air.

 

[Hydrozoan]

Yes. There are slight design differences, with diaphragm, without diaphragm, with and without schrader valve. Each has slightly different installation requirements but all do the same job, reliant on the higher compressibility of air.

Thanks. I had assumed they are essentially the same, performing similar functions, and the photographs of the Surecal ones look externally identical even though they get separate website pages - and the prices are identical too, I think.

 

[Spirit (of Glenans)]

Would I be correct in assuming that an expansion tank and an accumulator tank are one and the same thing?

I would have thought that an expansion tank is a specific requirement of a hot water system, to acommodate the expansion due to heating, much the same as in a domestic system, whereas an accumulator absorbs pressure from the pump, allowing water to flow without the pump switching on.

 

[Irish Rover]

I would have thought that an expansion tank is a specific requirement of a hot water system, to acommodate the expansion due to heating, much the same as in a domestic system, whereas an accumulator absorbs pressure from the pump, allowing water to flow without the pump switching on.

I believe you're correct - my point however was that I could buy something marketed as an accumulator tank and use it on the hot system as an expansion tank subject to adjusting the pressure if necessary.

 

[vyv_cox]

I would have thought that an expansion tank is a specific requirement of a hot water system, to acommodate the expansion due to heating, much the same as in a domestic system, whereas an accumulator absorbs pressure from the pump, allowing water to flow without the pump switching on.

The function is exactly the same in each case. Water pressure compresses the air in the upper (or diaphragm closed) part of the accumulator when either the pump is running or the water is heated. When the tap is opened the air pressure drives it out again. Accumulators are widely used in engineering applications for a variety of fluids, the design does not vary.

 

[Venus1]

I am finding this thread very informative
Given the above, if an expansion tank is installed, does that mean a pressure relief valve on the calorifier is not necessary?

 

[Irish Rover]

I am finding this thread very informative
Given the above, if an expansion tank is installed, does that mean a pressure relief valve on the calorifier is not necessary?

I'm sure the experts will be along to answer this but I'd imagine the answer is no. I'm assuming the ability of the expansion tank to absorb excess pressure is limited whereas the pressure relief valve is unlimited.

 

[vyv_cox]

I am finding this thread very informative
Given the above, if an expansion tank is installed, does that mean a pressure relief valve on the calorifier is not necessary?

A PRV is required. The calorifier is technically a pressure vessel and could burst under some circumstances,