S1 Cooling Fan

[daerider]

Does anyone know why the fan inside the chassis only runs when the steam boiler element is active? Anyone care to speculate?

Thanks,
Damon

[wgaggl]

The fan cools the solid state relay for the steam boiler heating element. Obviously passive cooling with a heatsink is sufficient for the lower power brewing group heating element.

[daerider]

The fan cools the solid state relay for the steam boiler heating element. Obviously passive cooling with a heatsink is sufficient for the lower power brewing group heating element.

Thanks for the response!

So what were saying here is that if I upgrade the SSR to a high quality 40amp version, I could probably do away with the fan altogether?

[wgaggl]

If you can find a SSR with a low voltage drop and a heatsink with a low enough thermal resistance, the answer is yes.

On thing to consider is, the "ambient temperature" that the heatsink sees in there isn't room temp. It's much higher.

Calculation example (enter your numbers here):

Ambient temperature 40degC
SSR Max operating temp 80degC
Heatsink temp diff: 40degC
SSR max voltage drop: 1.6V
Max current: 12A
Power to dissipate: 19.2W
Necessary thermal resistance of heatsink < 2C/W

That's based on Omega SSRL240 Series SSR, and FHS-1 heatsink.

Using FHS-2 heatsink in this example, the ambient temp inside the machine, could climb up to 57degC for proper operation; that is if you get that bulky FHS-2 in there; or if you find a SSR with a lower max. voltage drop @ 12A.

Wolfgang

[daerider]

Wolfgang,
I thought it was something very simple like that, I'm suddenly a huge advocate of miniture brushless fans inside the chassis of high quality espresso machines!

Thanks for the detailed response,
Damon