Replacing immersion heater thermostat in 90 build house, has no temp cut out

[pennine_lad]

Hi

The Baxter BT18 thermostat in immersion heater has failed and need to replace. This does not have an independent thermal trip built in. With a 90 build would this have been say in the element or was it not mandatory then?

Prefer to replace with a model without a cut out as have been reading reviews on Amazon where this and similar models keep tripping the cut out. It is not trivial to replace requiring a plumber to unbraze to swing out pipe as the header pipe is frustratingly located right above it, is this seemingly bad layout common?

Thanks.
David

 

[HERTS P&D]

Of course it has a cut out, turn off the power and remove the cap and post a picture.

Also it will be easy to get out and replace.

Andy

 

[Murdochcat]

If it’s tripping the thermal cut out, turn the setting down on the thermostat. This should fix it

 

[SUNRAY]

Of course it has a cut out, turn off the power and remove the cap and post a picture.

Also it will be easy to get out and replace.

Andy

Why 'Of course' Immersions without cutouts were available well into this century.

 

[pennine_lad]

To clarify, with no cut out meant one independent of the temp setting. The BT18 does not have one and shops state that must be used only if an independent cut out somewhere. Text below from TLC Direct.

The thermostat has failed so heats above the temp set on dial.

It is not easy to replace, the head of the thermostat is too big to clear the pipe have tried, the probe is not flexible.

David

BT18 spec:
18 inch Immersion Heater Thermostat

To fit 27 - 30 and 36 inch immersion heaters.

BRITISH MADE To BS 3955
13 amp rating.
Sealed stem, long lasting.

Without Cutout
Only suitable if you have secondary protection.

Temp Range: - 15°C - 65°C.

 

[HERTS P&D]

And again, it does have a cut out and it is easy to remove and replace. Just call a plumber.

Andy

 

[AndyPRK]

If the blue thermostat that has failed, it just pulls out. (After disconnecting wires)

 

[pennine_lad]

When remarked easy to replace was from the standpoint of the home owner, if the pipe was not above the fitting it would have been easy for home owner to do.
Is the cut out in the element it is not in the BT18 as the shops all state in their spec.
David

 

[pennine_lad]

If the blue thermostat that has failed, it just pulls out. (After disconnecting wires)

It does not pull out it is blocked by the pipe above it as photo shows.
David

 

[ericmark]

If the heater tank can handle boiling water, either metal or thermal setting plastic, there is no need for a cut-out. Although having one would be preferred. It is common that the thermostat cut-out is built into the thermostat and is resettable when there is more than one way to heat the water, as the other method may cause it to trip, thermal plastic should not be used where there are multi ways to heat the water, however my tank is thermal plastic, however the sound of water boiling should alert anyone as to what is going on.

2008 this happened

which killed the baby under the tank, the thermal plastic tank should have never been used, although most reports blame the use of an immersion heater without a cut-out, having lived in a house where the water often boiled, I can't understand how the noise did not alert others in the house.

The reset can be seen in this thermostat

and most do have them built it as shown.

 

[pennine_lad]

If the heater tank can handle boiling water, either metal or thermal setting plastic, there is no need for a cut-out. Although having one would be preferred. It is common that the thermostat cut-out is built into the thermostat and is resettable when there is more than one way to heat the water, as the other method may cause it to trip, thermal plastic should not be used where there are multi ways to heat the water, however my tank is thermal plastic, however the sound of water boiling should alert anyone as to what is going on.

2008 this happened View attachment 365038 which killed the baby under the tank, the thermal plastic tank should have never been used, although most reports blame the use of an immersion heater without a cut-out, having lived in a house where the water often boiled, I can't understand how the noise did not alert others in the house.

The reset can be seen in this thermostat View attachment 365039and most do have them built it as shown.

Thanks for the insight. The Baxter BT18 does not have a cut out though, there is no reset. The shops note it does not have one for this model.

 

[HERTS P&D]

Post a picture looking at the thermostat.

Andy

 

[SUNRAY]

And again, it does have a cut out and it is easy to remove and replace. Just call a plumber.

Andy

If it's a proper BT18 then the thermostat doesn't include a cut-out, I don't see a classic cut-out on the heater itself. It looks like the flex is terminated into the stat and it looks like the heater is connected to the other side of the stat. Obviously I don't see if there is anything lurking 'behind' the stat in this view.

There are 18" stats available which include a cut-out, this is my first google hit: https://www.screwfix.com/p/tesla-dual-safety-thermostat-18-/89445?

Can we have another pic, either from the other side or top view?

 

[AndyPRK]

Pipes not in the best place. But have you tried?

Stat may bend slightly or rotate the head around

 

[pennine_lad]

This is the head of the element with Backer BT18. The temp dial is not sprung with an overtemp trip.

Unfortunately the pipe will not flex at all to bring it past. The shop though sent a BT18 equivalent made by Cotherm and the probe rather than sitting near the head block centre is close to probe edge along one side so may be a chance to cut the original one out and slide this in.
A plumber is coming to fix other pipes so can let them decide.

David