Replacing an immersion heater thermostat with a cylinder thermostat.

[The Bedwetter]

I am having a problem with the thermostat that is located in an immersion heater element fitted to a direct HW cylinder (located in an attic). It operates properly for a few weeks and then for some reason the stat trips. As the element is 27” long I guess that sometimes it can be prone to bending slightly as it reaches peak temperature and makes contact with the thermostat.

Would it be possible to discard the element thermostat and replace it with a proper cylinder thermostat? This would appear to negate the ‘bending’ element problem but can anybody see any reason as to this arrangement not being acceptable?

Thanks for any advice.

 

[Reg Man]

Thought the thermostat was in a separate phial of the immersion heater element fitting. You can just unscrew the two contact wires and pull it from the phial. With the symptoms you have given, it sounds like the element is slightly pin holed and shorts out when it heats up. So change the whole element and might as well change the thermostat whilst your doing it.

 

[The Bedwetter]

Thanks for replying. Yes, the thermostat is in separate phial and I have tried replacing it on several occasions but, at some stage, regardless what thermostat is installed, it will trip. Hence my question about the bending element making contact with the sheathed section that houses the thermostat. Changing this type of stat for a proper cylinder type might perhaps deal with this issue.

You say the element could be pin-holed. Would this be likely on an element only 7 or 8 months old? It is an Incalloy type which I thought were supposed to be well protected.

 

[Leo21]

The new ones are carp. I've had to replace new ones quite a lot. Not sure if anyone makes a decent one anymore.

 

[PlumbBobBob]

a cylinder stat is completely different from an immersion stat, wired differently and operating differently. you cannot just substitute one for the other.

 

[jtsplumbing]

Incalloy immersion heaters are usely recommended for hard water area's, I cant see how you are bending the element to such an extent that it is touching the part that holds the temperature sensor ! as a Direct cylinder has got nothing else inside that will interfere with the fitting of a 27" heater ! If your cylinder is in the attic where is the cold water storage tank that supplies it ? or is it a case that you are trying to fit a 27" heater in a Fortic cylinder ??

 

[AWheating]

a normal cylinder stat does not have a non self resetting cut out, so no you cant change one directly for the other.

 

[Dotty]

a cylinder stat is completely different from an immersion stat, wired differently and operating differently. you cannot just substitute one for the other.

a normal cylinder stat does not have a non self resetting cut out, so no you cant change one directly for the other.

:iagree:

 

[AWheating]

the current would be totally different also, cant see a cylinder stat being designed to take the amps. It would need some simple to eletronics to diy it at a guess. It would not be advisable imo.

 

[kay-jay]

A cylinder stat is designed for indirect heat ie shutting a boiler down when heat satisfied.
A direct heat 3kw electrical immersion element relies on its own correctly rated stat. Crossing the two is likely to end in tears.....and an electrical fire