Is my SSR overheating or is it functioning normally?

[LondonBrewer]

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Hello everyone,

I've been coming to this site for the past year whilst planning and building my brewery, but have only just got round to registering. First off, I'd like to say what a great site and a great forum too.

I've just finished my build and am going through my final testing and control panel setup before my first proper brew. However, I might have a problem, so wanted to check first before pressing on with the first batch.

While testing my boil kettle element, I have noticed that the heat sink over the boil SSR is becoming very hot to the touch. I measured it with the tip of a Thermapen and it was reading around 40C (104F). Afterwards I opened the panel and noticed that there was a warm smell. I know that sounds weird. Not quite an electrical burning smell, but just like something was overheating.

Here are the conditions I was operating under:

I have built the 240v version of the panel as described on this website. All parts are the ones specificed, except the DPDT relays (they are rated at 80amp as these were cheaper, but that shouldn't make a difference?).

I am using the Auber SSRs with the individual heatsinks from Auber rather than the custom heatsink. I used the thermal paste supplied by Auber when sealing the heatsink to the SSR.

The possible overheating occurred in Automatic mode on the PID rather than manual (I was performing an autotune in case I want to do hop stands etc - I have not tried to operate in manual mode yet). The issue occurred as the water was heating up (i.e. I didn't get to the autotune part yet, I just switched off the panel when I realised how hot the heatsink was).

I might be mistaken about this so please correct me if I am wrong: I was under the impression that SSRs heat up due to rapid changing between open and closed? So if I am still heating the water it should only be open and not switching (the light is on 100% of the time) and therefore shouldn't get hot?

So my question is, is the SSR functioning normally and it is expected that the heatsink would become that hot, or is there something wrong with one of the components that could potentially cause this issue?

I might just be paranoid because I want everything to go well on my first brew, but to be honest I'd prefer not to burn the house down.

Anyway, thanks again for all the great info on this site.

All the best,

LondonBrewer

[kal]

40C is not very hot. The heat sink should get warm, because that means it's sucking heat out of the SSR. You don't want the SSR to get warm. Make sure you're using thermal grease between the SSR and heat sink and only use enough to get a very thin layer. (However too much will just impede heat flow from the SSR to the heat sink causing the heat sink to not get as hot).

As long as the heat sink is out in the open (not in the panel) and it is sized for the size of SSR you're using, you're likely ok.

Kal

[kal]

40C is not very hot. The heat sink should get warm, because that means it's sucking heat out of the SSR. You don't want the SSR to get warm. Make sure you're using thermal grease between the SSR and heat sink and only use enough to get a very thin layer. (However too much will just impede heat flow from the SSR to the heat sink causing the heat sink to not get as hot).

As long as the heat sink is out in the open (not in the panel) and it is sized for the size of SSR you're using, you're likely ok.

Kal

[LondonBrewer]

Hi Kal,

Thanks for getting back to me. Good to know that this is a normal temp for the heat sink. I think I'm likely getting a bit paranoid because I want to make sure everything is as it should be before firing up the system.

Thanks for the reassurance, first all grain brew can now get started.

Cheers,

LB

[Sketchin]

Just for a comparison, my CPU temp on my PC has gotten up to 85C or so with no long term effects. 40C is barely above ambient.