Immersion heater - 2 questions

ianto11

The overheating will be caused by the thermostats having failed but they're not expensive, the heating elements are obviously OK as they're boiling your water

https://www.advancedwater.co.uk/spare-012-583-0003.html

As a thought did the electrician check what the stats are set at ? as you can see from the pic, they're adjustable, maybe someones turned them full up.
You can check what the stats are set at yourself they're under the white covers...just be sure to switch off at the mains first.
You can change the thermostats without the need for draining down the cylinder they fit inside a pocket on the immersion

If it were me I'd get the thermostats replaced and a new vessel...the comments on the quote are all merely disclaimers

Anyone working on an unvented cylinder is required to have a G3 ticket by law...so not a DIY'er

ssm90

ianto11 wrote: »

The overheating will be caused by the thermostats having failed but they're not expensive, the heating elements are obviously OK as they're boiling your water

https://www.advancedwater.co.uk/spare-012-583-0003.html

As a thought did the electrician check what the stats are set at ? as you can see from the pic, they're adjustable, maybe someones turned them full up.
You can check what the stats are set at yourself they're under the white covers...just be sure to switch off at the mains first.
You can change the thermostats without the need for draining down the cylinder they fit inside a pocket on the immersion

If it were me I'd get the thermostats replaced and a new vessel...the comments on the quote are all merely disclaimers

Anyone working on an unvented cylinder is required to have a G3 ticket by law...so not a DIY'er

Okay so the fault here is with the thermostats which is what is causing the overheating. And the expansion vessel is a secondary issue with it failing.

I just checked, I am unable to remove the white cover, it seems to be screwed on. I could peer through the gap behind the white cover but couldn't tell if there was some sort of a heating setting which is odd. I might try unscrewing the cap and having a look tomorrow.

So just to sum up, best thing to do here would be to replace the thermostat and the expansion vessel? Th heating elements and the cylinder seem to be working okay I guess.

And for future maintenance, is there definitely no insurance cover for this? I find that so hard to believe as you can insure almost anything!

ianto11

I'd swap out the thermostats first...I would argue these can be replaced by an experienced DIY'er competent with electrics ( but not in court ) as they just plug into the immersion, and as such there's no intervention in the cylinder plumbing and safety devices.
Did the electrician confirm that the expansion has failed ?

If you turn the immersions off so the waters cold, you can then remove the little black cap on top of the expansion, there's a valve under there like a car valve. You can then give a short press on the little pin in the middle of it in with a small screwdriver.
If air comes out it's OK...however if it's failed water will come out, hence the reason for making sure the cylinder is cold

You probably can get standalone insurance...like boiler cover, but it would probably require annual inspections and I'm pretty sure because of the nature of it the expansion still wouldn't be covered

ssm90

ianto11 wrote: »

I'd swap out the thermostats first...I would argue these can be replaced by an experienced DIY'er competent with electrics ( but not in court ) as they just plug into the immersion, and as such there's no intervention in the cylinder plumbing and safety devices.
Did the electrician confirm that the expansion has failed ?

If you turn the immersions off so the waters cold, you can then remove the little black cap on top of the expansion, there's a valve under there like a car valve. You can then give a short press on the little pin in the middle of it in with a small screwdriver.
If air comes out it's OK...however if it's failed water will come out, hence the reason for making sure the cylinder is cold

You probably can get standalone insurance...like boiler cover, but it would probably require annual inspections and I'm pretty sure because of the nature of it the expansion still wouldn't be covered

Thanks a lot for your help ianto! I have reached out to a number of local tradesmen to get a quote to replace the expansion vessel and thermostat. The original quote of £192 seems steep!

Yes, the electrician did do the 'hiss' test and no air came out which suggests that it is actually flooded.

Where exactly is the immersion and thermostats? I thought it would be immersed in the water? Sorry if I'm being stupid here but I thought it's an internal component. If they're not, where exactly are they, are they attached to the elements?

I've reached out to a couple insurers...fingers crossed but I don't have much hope. More surprised than anything to be honest!

ianto11

ssm90 wrote: »

Yes, the electrician did do the 'hiss' test and no air came out which suggests that it is actually flooded.!

Not necessarily, I would've expected water to come out...maybe it just lost the charge ?

ssm90 wrote: »

Where exactly is the immersion and thermostats? I thought it would be immersed in the water? Sorry if I'm being stupid here but I thought it's an internal component. If they're not, where exactly are they, are they attached to the elements?

The immersions are screwed into the cylinder, so are "immersed" in water and look like this

https://www.amazon.co.uk/Heatrae-Sadia-Megaflow-Immersion-95606963/dp/B00GRQYQQK

top part is the element...the bottom one with the white top is the thermostat and plugs into a "pocket" in the immersion...not in contact with the water, registers the heat of the water through thermal transfer and controls accordingly

ianto11

To better understand "immersion" and "thermostat" have a look at this clip

https://www.youtube.com/watch?v=s72fumgMObM

from 6mins 30 you'll see him remove the thermostat, and you can see the immersion still in the cylinder.
Although this isn't for your exact model of immersion...it will be very similar

ssm90

Brilliant, thanks very much for that. I'm going to watch those videos and also try recharging the vessel again (though last time that didn't work). I'm also going to remove the white cover and see if I can reduce the temperature setting.

If neither works, then I'll have to get them both replaced. Quotes received so far are between £200 - £300 per job so I'm hoping I can resolve it myself!

jcontest

I would find it odd if the expansion tank has failed.
Try charging it up!...


And what do you mean "It Floods"... Water comes out of the unit through the white pipe or something else?

ssm90

jcontest wrote: »

I would find it odd if the expansion tank has failed.
Try charging it up!...


And what do you mean "It Floods"... Water comes out of the unit through the white pipe or something else?

Yes sorry my choice of words probably wasn't the best. By flooding, I meant it kept overflowing through the white pipe because i've been told the expansion vessel is 'flooded' rather than half water/ half air as it should be.

I have tried recharging the vessel before and it didn't work which is why I am sceptical. Also the current expansion vessel is also different colour/make to the cylinder which suggests that the one before it also failed.

ssm90

https://ibb.co/m80N3sZ

Please see image above, I managed to take the white cover off from the Bottom element and this is what I can see. Is the red arrow dial thing the thermostat setting? If so, it was on the + sign which I imagine is Max. I have now moved it a bit lower to towards the - sign which I imagine is Min. Unfortunately, I am unable to remove the white cover of the Top element.

Do the two elements work at the same time? I.e. can one be switched on or off separately or does one act as a booster? From what I can see they're both connected to the same point in the wall.

What is the recommended setting to have the thermostat on between the + and - signs for a 2 bed flat with 1 resident in?