Replacement calorifier

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Siftasam

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Hi all.
Our very early (30 years) isotemp calorifier has corroded through our last spare immersion and none of our type are now available.
We are undecided as to whether to replace with new ss version of the same - 24ltr with 750w immersion or to go for a Hotpot/Surcal/C-warm model. of similar size.
Our Isotemp has been fantastic- only needing 3 replacement immersions and one of those was due to our having no water in the tank!
Any experience of the new Isotemp or other makes would be nuch appreciated.
 
My boat came with a calorifier that appears to be a Sigmar Marine model, one with a plastic outer shell. Seems to do the job - has been on the boat some years.
 
I fitted a Surecal, am pleased with it and found the company helpful - though I have no experience of others who might have been equally so.
 
I would go with Surecal. Hotpots are Surecal, marketed by ASAP, but with no non-return valve and hosetails for the hot/cold water instead of pushfit connections.

Not though that Surcal calorifiers will need an accumulator and an expansion tank fitting, if not already present.
 
Many thanks everyone.
PaulRainbow said:
I would go with Surecal. Hotpots are Surecal, marketed by ASAP, but with no non-return valve and hosetails for the hot/cold water instead of pushfit connections.

Not though that Surcal calorifiers will need an accumulator and an expansion tank fitting, if not already present.
Click to expand...

Looks like Surcal are front runners.… our concern was the requirement for the expansion tank.
Has been suggested that the copper tank may split without one although our old copper isotemp did not have one, but maybe thicker copper in 1990 !
 
Copper has natural antibacterial properties so is slightly better than stainless in that respect. Lack of an expansion vessel is only a problem if there is nowhere for the heated water to expand to, such as if a non return valve is fitted.
 
Siftasam said:
Many thanks everyone.


Looks like Surcal are front runners.… our concern was the requirement for the expansion tank.
Has been suggested that the copper tank may split without one although our old copper isotemp did not have one, but maybe thicker copper in 1990 !
Click to expand...
I have a Seaward calorifier, 22 years old and still good. Has never had an accumulator or expansion vessel, I just have a 1/2 litre bottle to collect anything that is discharged from the pressure relief valve (this is reassuring as I know the prv is working and gets occasional excercise)

Www.solocoastalsailing.co.uk
 
Siftasam said:
Many thanks everyone.


Looks like Surcal are front runners.… our concern was the requirement for the expansion tank.
Has been suggested that the copper tank may split without one although our old copper isotemp did not have one, but maybe thicker copper in 1990 !
Click to expand...

Surecal have non-return valves in the cold supply inlet, so no room for expansion, hence the requirement.
 
Last edited:
PaulRainbow said:
Surecal have no-return valves in the cold supply inlet, so no room for expansion, hence the requirement.
Click to expand...
Oh, I though all calorifiers had a nrv in the cold supply to stop the expanding hot water being forced back into the cold system, before the prv opens, and potentially damaging the valves in the freshwater pump, my Seaward/Whale one has a nrv.

Www.solocoastalsailing.co.uk
 
Last edited:
Plum said:
Oh, I though all calorifiers had a nrv in the cold supply to stop the expanding hot water being forced back into the cold system, before the prv opens, and potentially damaging the valves in the freshwater pump, my Seaward/Whale one has a nrv.

Www.solocoastalsailing.co.uk
Click to expand...

A lot of older calorifiers didn't have NRVs. Surecal ones do, but the ones they rebadge for ASAP don't have them, when you first turn the cold tap on the water is luke warm.
 
Interesting that the Hotpot doesn’t have a nrv. It’s interesting also that asap and surcal both show the expansion tank fitted in the hot water outlet pipe.
Jabsco on the other hand advise fitting the expansion tank in the COLD water inlet pipe after the nrv.
i.e. water pump >accumulator>nrv> expansion tank> calorifier.
This makes sense in a way as why drain out precious water from the hot side expansion tank on first use.
If the Hotpot has no nrv the alternative Jabsco method would be possible ?
 
Re PaulRainbow’s comment about older calorifiers. I can confirm that our Isotemp does/did not have one. However our pipework is flexible 1/2” (12mm) old style not the modern hep2o rigid pipework. Undoubtedly this could allow some relief for excess pressure ? - especially as the water warms it up…
 
Siftasam said:
Hi all.
Our very early (30 years) isotemp calorifier has corroded through our last spare immersion and none of our type are now available.
We are undecided as to whether to replace with new ss version of the same - 24ltr with 750w immersion or to go for a Hotpot/Surcal/C-warm model. of similar size.
Our Isotemp has been fantastic- only needing 3 replacement immersions and one of those was due to our having no water in the tank!
Any experience of the new Isotemp or other makes would be nuch appreciated.
Click to expand...

Make sure you really can't get a new immersion. I thought it couldn't be bought and replaced my 30 year old isotemp only to discover (1) they could be bought (2) it was just a bad connection. Not sure where I saw them - maybe SVB?
 
Thanks dgadee. We intend to remove the offending unit tomorrow and will dismantle the immersion for a thorough check. SVB have a good range of spares of all sorts. Thanks for the suggestion..
 
Siftasam said:
Thanks dgadee. We intend to remove the offending unit tomorrow and will dismantle the immersion for a thorough check. SVB have a good range of spares of all sorts. Thanks for the suggestion..
Click to expand...

There is one here: Isotemp 750 Watt Immersion Heater Element (for Old Orange Units but pretty expensive. I am sure I saw it cheaper, but cannot remember where.

Edit: and here Isotemp Heater Element SEE00002HA - Magic - 220v x 750w at a lower cost if it is the same type.

I think it was SVB who had it cheapest. Just found this: Heating Element for older models (orange) 750W/220V only 65,95 € | SVB
 
Siftasam said:
Re PaulRainbow’s comment about older calorifiers. I can confirm that our Isotemp does/did not have one. However our pipework is flexible 1/2” (12mm) old style not the modern hep2o rigid pipework. Undoubtedly this could allow some relief for excess pressure ? - especially as the water warms it up…
Click to expand...

With no NRV the some pressure in the calorifier can be relieved into the cold system, that would often have an accumulator tank.

The Surecal NRV is fitted into the brass pushfit connector on the calorifier itself so the expansion tank cannot be fitted the Jabsco way. But, it doesn't matter if it's fitted how Jabsco say or if it's fitted to the hot outlet, it still relieves the pressure the same way.

ASAP Hotpot calorifiers are made by Surecal, but unlike Surecal badged ones they do not have NRVs and the domestic connections are hose tails rather than pushfit connections.
 
PaulRainbow said:
With no NRV the some pressure in the calorifier can be relieved into the cold system, that would often have an accumulator tank.

The Surecal NRV is fitted into the brass pushfit connector on the calorifier itself so the expansion tank cannot be fitted the Jabsco way. But, it doesn't matter if it's fitted how Jabsco say or if it's fitted to the hot outlet, it still relieves the pressure the same way.

ASAP Hotpot calorifiers are made by Surecal, but unlike Surecal badged ones they do not have NRVs and the domestic connections are hose tails rather than pushfit connections.
Click to expand...

I had to add an expansion tank after replacing the Isotemp with a Surecal and putting a cockpit shower in. Was impossible to control temp at shower without one. Not sure why two systems seemed different or if it was simply adding a shower take off near the tank.
 
Many thanks everyone.
Checked out the immersions available and suggested for ‘Old orange ‘ Isotemp…think ours is the dinosaur as is,apparently,an even older version now extinct..
So- have ordered a 15l Hotpot from ASAP and a small expansion tank to suit. Already have an accumulator fitted and found an nrv in spares box (never fitted).
Old tank finally removed..….we are not talking about that …
Dgadee, we checked connections as you suggested. All were good but immersion showed was shorting out to earth with multimeter, so duff.. It was the trip throwing out which initially alerted us to a problem - no wonder.
Thanks for your comments re cockpit shower. We have a deck shower and used it with great care for the reason you mentioned. Be grand if that gets sorted out as well!
Thanks again to everyone for your advice.
 
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