Metal Diecast box as Triac heatsink?


Am almost finished my hardware build of a Solar Router to get spare power into the immersion heater. Due to layout of house I will have about 20m of cable between my Arduino and the output board with the Triac. This seems like a lot but is only about 10 ohms of resistance.

I'm intending putting the Triac in a metal die-cast box in my airing cupboard - the wiring will be very easy for me to do.

The airing cupboard is obviously quite warm - so was wondering what people's views were on the idea.

I was thinking about using a box of about: 188 x 120 x 57 mm. The triac would be mounted on the inside of the box which would be earthed. The only other think in the box would be the small PCB.

Thanks in anticipation - Rob

Brian D's picture

Re: Metal Diecast box as Triac heatsink?

The attached photo shows my remote diverter which uses a die-cast box with a substantial heatsink.

The unit is too hot to touch when running at full tilt.


Robert Wall's picture

Re: Metal Diecast box as Triac heatsink?

I measured a Spiratronics Diecast Aluminium Box 187x118x57mm, Code: FW2-910 to be about 2.4 °C/W, with the triac bolted to the long side. With the dissipation at 15 W,  the box should get up to around 55 °C, the tab 80 °C and the junction 89 °C - still comfortably below the maximum.

LC23's picture

Re: Metal Diecast box as Triac heatsink?


Thanks - that's excellent feedback, much appreciated.

Regards - Rob

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