immersion heater safety cutout problems

[tracey2109]

Hi, I'm really sorry if this has been asked before - have had a look and couldn't find it.

We have an immersion heater that we use when we are not using our coal fire to heat our water (we don't have central heating). However we had to have the element replaced and since then we have been having problems. We've found out that this is due to the new safety cutout required by law and the fact that our coal fire must over heat the water causing the immersion heater to trip even when it is not on. We can reset the immersion heater each time but were wondering if there is any way we could avoid this as it is not really the most ideal thing.

Thanks very much for any help,

Tracey

 

[BS3036]

The cutout is often built into the thermostat which is a replaceable item. I believe that thermostats are still available without the safety cutout because they are still required in situations where the cutout is not appropriate.

In a case like yours, where you can already heat the water to higher temperatures than the cutout wants, it would seem logical to use one of these, especially as you have already been doing this for years.

I am however, not an expert, and there is of course a potential risk involved which this cutout is supposed to reduce.

 

[ColJack]

do you have a header tank for it? is is in the loft perhaps?

you have to have the cutout in these things to stop what happened to that little girl..
the water boiled and back fed to the loft tank and overflowed, scalding her in her bed..

 

[BS3036]

That's quite true, Col. Unfortunately, in this case, the cutout won't stop the coal fire from doing exactly the same. I guess you'd need a zone valve to divert the excess heat to a heat dump. Not traditional equipment though.

I wonder if a different forum might better qualified to make suggestions about heating systems?

 

[Steve]

A metal tank. Wont melt if the boiling water gets in it. Still not good though.

 

[RF Lighting]

Like Steve says, providing the header tank is metal, then an over temperature cut out is not required.

If the header tank is plastic unfortunatly the cutout is required, and I'd also be a bit concerned about the safety of a system that could heat the water so hot and discharge it into a plastic header tank, but I'm no plumbing expert.

 

[tracey2109]

hi, thanks for all your help. we don't have the worries about the tank as we are in a bungalow so the tank is in our bathroom and is metal. mum says also that our overflow goes outside and not into our cold water tank to prevent spare hot getting in there.

 

[flameport]

If your coal boiler is heating the hot water to a temperature which causes the immersion heater cutout to operate, there is something very wrong with the system.
At the very least, there should be somewhere for the excess heat to go - usually a suitably sized radiator in the bathroom which cannot be turned off.

Although your header tank may be metal, this does not mean it is safe.
Metal tanks (particularly old ones) can fail. So can hot water cylinders.
You don't want boiling water coming out of your taps - it will cause serious injury to someone.
Overflowing outside is no good either - what if the boiling water overflowed as someone was walking past?

This is not an electrical problem.
You need to get the whole system checked by a heating engineer familiar with solid fuel/gravity hot water systems.