Immersion thermostat

TerryOC

My immersion is heating the water too hot. I took the top off the heater but I cannot see the actual thermostat. I know you can buy replacement thermostats in Woodies. I attach photo of the item, perhaps someone can advise .

westyIrl

That immersion doesn't appear to have any internal thermostat (or TCO for that matter). Does the cable feeding the immersion come directly from the switch or is there an intermediate thermostat on it? Either way, if the water is too hot, I'd be looking at sticking in a new immersion personally.

Or maybe it is there and I can't see but what is under where the white wire that comes from the two bonded elements? The thermostat, if it is there, would lie between that white and feeding blue wire. It's just not clear on picture whats down there. Looks a very old immersion imo.

FAMLEE

Looks like there is no thermostat in that, so it will keep heating until it boils & vents.. maybe just put it on long enough to heat the water hot enough for use (bath/washing up etc.) use your hand on the top pipe to gauge. 45mins/1hour should get it up to 65-80c?

TerryOC

westyIrl wrote: »

That immersion doesn't appear to have any internal thermostat (or TCO for that matter). Does the cable feeding the immersion come directly from the switch or is there an intermediate thermostat on it? Either way, if the water is too hot, I'd be looking at sticking in a new immersion personally.

Or maybe it is there and I can't see but what is under where the white wire that comes from the two bonded elements? The thermostat, if it is there, would lie between that white and feeding blue wire. It's just not clear on picture whats down there. Looks a very old immersion imo.

Thanks for your reply. You are correct, it is very old. I'm in the house 25 years and it hasn't been changed in that time. I'd say it was there from mid 1970's when the houses were built. I think it's only in the last 6 months or so that I noticed the top of the cylinder being very hot. I'll get another photo tomorrow.

antix80

While you're getting a thermostat, get one of these too.. Horstmann E15 Electrisaver Electronic Push Button Boost Timer Switch
https://www.amazon.co.uk/Horstmann-E15-Electrisaver-Electronic-Button/dp/B004NOXOMK

Made my life a lot simpler!

John.G

Its probably a bit like mine (1972 and still working A1), mine is a dual immersion with the (red) sink/bath c/o switch in the cover, and and I think two thermostats, (60C/80C)

As above, advise to get a replacement immersion which will incorporate a hi limit stat as well as the settable control stat.

I see your is 06-73 so the warranty is well out but you didn't do too bad.

TerryOC

John.G wrote: »

Its probably a bit like mine (1972 and still working A1), mine is a dual immersion with the (red) sink/bath c/o switch in the cover, and and I think two thermostats, (60C/80C)

As above, advise to get a replacement immersion which will incorporate a hi limit stat as well as the settable control stat.

I see your is 06-73 so the warranty is well out but you didn't do too bad.

yes, not too bad if it's been working for over 40 years. Could I tackle installation of a new immersion myself? I have seen the YouTube videos describing how it's done, but I am aware of the danger of damaging the copper cylinder. I'm generally ok at DIY but won't take risks. What would it cost me to get a plumber in to do the work?

John.G

I removed mine ~ 10 years ago and refitted it to a solar/oil twin coil cylinder so I wasn't worried about damaging the old cylinder even though I didn't have any particular problem in removing it. I just shut off the cold feed to the cylinder, opened a hot tap and let it full of water, I then got a hammer and a length of round bar and gave the immersion boss (hex) a few judicious belts anticlockwise and got the loan of a immersion socket with twin handles (very important) and was able to unscrew it reasonably easily.

I think though that you should be prepared to have to renew the cylinder as it may be weakened after all these years of service and the necessary tapping and force on the immersion may well cause it to spring a leak.

westyIrl

TerryOC wrote: »

yes, not too bad if it's been working for over 40 years. Could I tackle installation of a new immersion myself? I have seen the YouTube videos describing how it's done, but I am aware of the danger of damaging the copper cylinder. I'm generally ok at DIY but won't take risks. What would it cost me to get a plumber in to do the work?

I've changed a many of them over the years. Generally, and I mean generally, in my experience the older tanks are a bit stiffer due to having a bit thicker wall in them and so can be somewhat more forgiving. Switch off cold feed from tank into bottom of cylinder and run a few hot taps to take off whatever water you can.

I'd be more inclined to get an immersion wrench that you can put a cheater bar on such as https://www.electricalworld.com/en/ie/Sealey-Flat-Immersion-Heater-Spanner/m-5197.aspx?PartnerID=73&utm_source=google&utm_medium=shopping&utm_campaign=Ireland&gclid=EAIaIQobChMImMHyv5zm5gIVQbDtCh0dXAUREAQYByABEgL9-PD_BwE and torque it off rather than using any form of impact. Not saying I'm correct, and impacting can work better in some situations, but just the way I would go about it before trying impacting. Try to minimise any side force on the wrench that causes the tank to deflect if that makes sense. i.e. put torque on wrench squarely. If you feel the torque is bit too severe, try a couple of tapping blows from hammer.

The most important step is to thoroughly clean the surface where the gasket of the new immersion heater seals to the tank. I use a bit of wire wool for the subborn stuff but get the old residue off. A hand squeeze of the wrench on the new immersion is generally sufficient to seal it up ok. It's really not a bad job at all once you are competent with the electrics.

As mentioned above, the tank could fail so be prepared for that eventuality but take your time.

Jim

Doolittle51

An easier option would be to install one of these:

https://www.screwfix.ie/p/flomasta-cylinder-thermostat-230v/6803K?gclid=EAIaIQobChMIgM_Z7f3m5gIVleh3Ch2ZyA_JEAQYAiABEgJE6fD_BwE&gclsrc=aw.ds#product_additional_details_container

An electrician could do this in about 10 minutes. No need to mess with plumbing that's over 40 years old. However, if you want to replace the immersion, be prepared to replace the whole tank. It's probably worth considering this anyway. New tanks are fully insulated & the water will stay warmer a lot longer compared to your existing tank. Would save you money in the long run if you use the immersion every day.

John.G

Yes, it would be prudent to try and remove without impacting first but I think that using a T socket with 2 lengths of suitable pipe will put less stress on the immersion/cylinder due to the torque couple (but might be wrong).

External stat should work but personally I would be a bit uneasy using it, the normal internal stat switches the neutral (dual immersion) but I think that's not allowed with a external, I presume that a electrician can still use it (external stat) to switch the live or lives to conform to regs and practical safety.

TerryOC

westyIrl wrote: »

I've changed a many of them over the years. Generally, and I mean generally, in my experience the older tanks are a bit stiffer due to having a bit thicker wall in them and so can be somewhat more forgiving. Switch off cold feed from tank into bottom of cylinder and run a few hot taps to take off whatever water you can.

I'd be more inclined to get an immersion wrench that you can put a cheater bar on such as https://www.electricalworld.com/en/ie/Sealey-Flat-Immersion-Heater-Spanner/m-5197.aspx?PartnerID=73&utm_source=google&utm_medium=shopping&utm_campaign=Ireland&gclid=EAIaIQobChMImMHyv5zm5gIVQbDtCh0dXAUREAQYByABEgL9-PD_BwE and torque it off rather than using any form of impact. Not saying I'm correct, and impacting can work better in some situations, but just the way I would go about it before trying impacting. Try to minimise any side force on the wrench that causes the tank to deflect if that makes sense. i.e. put torque on wrench squarely. If you feel the torque is bit too severe, try a couple of tapping blows from hammer.

The most important step is to thoroughly clean the surface where the gasket of the new immersion heater seals to the tank. I use a bit of wire wool for the subborn stuff but get the old residue off. A hand squeeze of the wrench on the new immersion is generally sufficient to seal it up ok. It's really not a bad job at all once you are competent with the electrics.

As mentioned above, the tank could fail so be prepared for that eventuality but take your time.

Jim

Good advice Jim, thanks

DublinDilbert

If you are changing it get a blade and cut around the gasket / washer, this will also help free it up. In the past I’ve even got junior hacksaw blade to remove parts of the washer. Once the washer isn’t applying much force, it’s just the threads that are mainly holding it.