Sourcing an IH stat c/w in-built o/heat

[Softus]

Please does anyone know where I can get a Pullin 18" rod stat with an in-built overheat stat?

This one has to fit under a cap on top of a dual element immersion boss - the faulty one that I've removed measures about 20mm from centre of rod to the extermity of the head - all other stats I've seen are bigger than this and prevent the cap fitting back on properly.

 

[kai]

I think that the dual element ones with separate stats are no longer made, you could try the local plumbers merchants with old stocks lying about.

When my dual element immersion failed, it was impossible to source a correct replacement, so the tank has to be replaced with a modern type, with two side entry elements instead.

 

[Softus]

Thanks for that information kai.

My customer isn't going to wear the idea of a new cylinder because one stat has failed, so I think that I have to fit a non o/h model so that it will fit within the cap.

Given that this is a flat, with no living area vertically below the cold storage cistern, I believe this will be safe.

However, you've given me another idea, which I should have thought of earlier (more temple striking with 18" adjustables), which is to ask a supplier of the dual element assemblies.

I know you said that they're obsolete, but this one looks promising:
http://qvsdirect.co.uk/acatalog/QVS_Direct_Immersion_Heaters___Thermostats_282.html

 

[Pensdown]

You could always fit normal tank stats, one to control the water temp and one wired in series set higher as the overheat stat. External stats work fine to control the tank temp from a boiler, why not from an element?

 

[Softus]

I appreciate your helpfulness, and whilst I understand your idea I don't think it can be made to work with dual elements and two circuits.

 

[Pensdown]

I thought you were just replacing the stat in one of the elements

I don't have an 18" spanner to knock myself round the head with so I'll whip myself with some test leads instead

 

[plugwash]

one idea, you could fit a bath/sink style immersion heater and then fit a supply changeover switch to use for boost power in the day.

you'd just have to remember to switch it back to bath mode at the same time as switching it back onto the E7 supply after your boost operation. This would also give you the advantage of being able to heat a full tankfull during the day if need be.

 

[Softus]

I thought you were just replacing the stat in one of the elements

Ah, I see. Just in case I haven't made it clear, the IH is a special one that is actually two elements mounted on one boss, top-mounted, also with two rod stat pockets. As you can imagine, things are a bit crowded under the cap!

...so I'll whip myself with some test leads instead

Try as I might, I can't resist the obvious question - please can I watch?

one idea, you could fit a bath/sink style immersion heater and then fit a supply changeover switch to use for boost power in the day.

you'd just have to remember to switch it back to bath mode at the same time as switching it back onto the E7 supply after your boost operation. This would also give you the advantage of being able to heat a full tankfull during the day if need be.

Thanks for the suggestion plugwash, but I don't know what a bath/sink style immersion heater is. In any case, given that everything is fine except for one stat, I don't think the customer would be very impressed if I charged for fitting a new timer and a new heater and required him to have to remember to do something every day!

 

[kai]

This type of element is now obsolete, and no longer made according to several plumbers merchants. Try replacing the tank with a modern one containing two side entries. Tough, but there is no viable alternative.

 

[Softus]

This type of element is now obsolete...

Hm. Since your earlier post, in which you also said that you thought they were obsolete, I Emailed QVSW; here's their helpful reply:

[code:1]Hi
As far as i'm aware any of our svnvkl stats fit the dual immersion heater we sell.
kind regards
[name withheld to protect privacy][/code:1]

And here's an image of said product on their web site:

Try replacing the tank with a modern one containing two side entries. Tough, but there is no viable alternative.

If I can't get a thermostat to fit within the existing cap, I'll be fabricating a bespoke cap - I think I can just about do this for less than the cost of a new cylinder, two IHs, a bunch of fittings and the best part of a day's labour