Convector heater component ident

[RWD3M]

Hi all,

I haven't been here for a while and the last time I was you helped me fix my old Vax, which is still working a treat by the way!

I now have another electrical problem which I'm hoping for a little help with please.

I have a wall mounted convector heater that has recently stopped working. After confirming the obvious stuff (power supply, fuse etc) I took it off the wall and took a look inside. The heater is only a couple of years old and as expected, continuity checks all the way from power in, through the timer, thermostat and on/off switches, all checked out ok.

Where it didn't check out ok was here:



I'm guessing this is some sort of thermal trip and it's now open circuit. There is no evidence of burning or overheating so far as I can tell, it just stopped working and now it gets rather chilly in my shed!

Is this an item I can replace? if so any ideas how I might go about identifying it?

If I shouldn't, please let me know.

The heater wasn't especially expensive, I think £30 or so, probably from Argos or the like, but I'd rather not just throw it in the bin for the want of £3 component!

Regards,

Richard

 

[kenny256]

It is a thermal fuse that opens if the temperature exceeds the rated Temp. Uses a wax pellet that melts and a spring action causes it to go open circuit. Usually there are markings on the part that can be decoded to determine the temperature set point and a replacement can be installed.

They didn't intend for it to be replaced since it is riveted into place, but rivets can be drilled out and new rivets used to reassemble. Or it may be easier to leave the leads of the old fuse in place and mechanically attach (metal barrel crimp) the leads of a new one.

[edit] there appears to be markings on the brass portion, maybe 180° ?
The brass and copper section appears to be a thermostat of sorts, so it may be sold as an entire assembly of thermostat with fuse.

 

[RWD3M]

Thanks Kenny, I'll take a closer look but didn't notice any markings earlier.

 

[RWD3M]

Just taken another look and there's some numbers on the tag on the LH side, 130 deg?

 

[bertus]

Hello,

@RWD3M
It could be that the bimetal switch cuts out at 130 degrees.
Could it be the thermo fuse has a slightly higher value to cut out when the bimetal switch sticks?

Bertus

 

[RWD3M]

I might be able to check that.

I'm off for my dinner now so will get back on thei in the morning.

Thanks Bertus and Kenny for your help so far.

Richard.

 

[RWD3M]

Good morning gents,

I couldn't come up with an easy way of checking the bi-metallic switch but it seems that the bay of evil is awash with thermal fuses, now that I know what they are!

I've ordered 130 and 150 degree fuses so will try the 130 first and see how I get along.

Many thanks again for your help and advice.

Best Regards,

Richard.

 

[bertus]

Hello,

You can not solder the thermal fuses.
I would use some bolts to fix them on the holes.

Bertus

 

[RWD3M]

Thanks Bertus.
I did wonder why they were rivetted in place. Aluminium perhaps?
I should have something small enough to fit.

 

[bertus]

Hello,

Rivetting does not create heat.
Heat would already blow the thermal fuse.

Bertus

 

[RWD3M]

Hello,

Rivetting does not create heat.
Heat would already blow the thermal fuse.

Bertus

Oh yeah! Never thought of that!!!

(That's not meant to be sarcastic, I really hadn't thought of that)

 

[shrtrnd]

Hopefully, the manufacturer used that terminal connector to mark the rating of that thermal fuse, …..
(so you have what you need).
I wanted to mention that the thermal fuses USUALLY have the value printed on them, BUT
they are also color-coded with the epoxy holding the lead in place at the end of the thermal fuse.
You can look up the rating on a chart (internet search) and the chart will show you the rating of the
thermal fuse by the color of the epoxy surrounding the lead of the component.

 

[RWD3M]

You're right!

I've just removed it and is is indeed printed on it. But by 'eck, was it hard to see! I had to take a picture of it and blow it up (metaphorically speaking!) to read it.



157 degrees apparently!

More ordered.

Many thanks,

Richard.

 

[bertus]

Hello,

It is indeed a 10 A 157 C thermal fuse:
https://www.tme.eu/en/details/bf157/thermal-fuses/aupo/



BF series datasheet: https://www.tme.eu/Document/bdc09498537597553d25678f42df7883/BF.pdf

Bertus

 

[RWD3M]

Thanks Bertus,

I got it all back together yesterday and it's working fine again.

I used two small self tapping screws in the end, seems to have done the job.

No longer suffering sub-zero temperatures in my shed!

Regards,

Richard.