Burnt out boiler timer

[lshelley]

Hi guys,

I've been using a Grasslin Towerchron QE1 immersion heater timer since moving into this house about 9 months ago, without problem. We only have the boiler (3kw) turned on for half an hour in the morning and half an hour in the evening using the timer. About a week ago, we came home to find it completely burnt out.. the plastic around the live feed to the boiler was melted completely beyond use. The wires from the timer to the boiler only look like 1.5mm, is that big enough?

So I've gone on eBay and bought a new QE2, and wired this in. I've trimmed the wires back to remove any damaged bits etc. Switched it on this morning and it seems to be working. Went back 15 minutes later and I've noticed this timer is also getting very hot, almost to the point of burning the skin. I'm thinking this can't be normal, but then I am not sure what to do about it next. The main heat seems to be coming from inside the timer itself and not the area around the connector. Does that sound like another timer fault? I never really paid attention to how hot the old timer was getting until being hit my the smell of melted plastic. Any advice is appreciated.

Thanks, Liam

 

[EFLImpudence]

It would appear that these timers are not suitable for immersion heaters but are intended for use with boilers.

You need a 16A timer that will be marked as intended for immersion heaters.

The cable you mention will be sufficient for the current although normally a 2.5mm² heat-proof cable is used. Again, this will be marked as specifically for immersion heaters if you are using the DIY outlets.

example

To remove confusion: Boilers are (usually) white boxes hung on the wall.
Immersion heaters are elements fixed in a water tank.

 

[bernardgreen]

It would appear that these timers are not suitable for immersion heaters but are intended for use with boilers..

Correct.... The manual says

Dimensions 156x85x42 [mm]
Power supply 240V/50Hz
Rating 5A (2A)/240V, per channel

5A and not 16A as required for an immersion heater