Another fridge drilling question..

[Matt in Birdham]

I am about to spend a bit more time on my fermentation fridge, fitting a Brewpi and generally tidying it up.
I know that the answer to "can I drill here?" questions is always "it depends", but hopefully there might be some general rules that can help..

My fridge is an old Frigidaire Larder Elite. Just one big fridge section with the standard compressor hump at the bottom.

The first thing I want to do is drill into the back of the vertical part of the compressor hump. Just a couple of small holes for shallow SSR mounting screws. My guess is that wouldn't be any gubbins in this area - it would be fairly hard to work any cooling coils around the multiple bends required, for little return. This area also does not seem to get cold to the touch when the fridge is on. There doesn't seem to be an easy way to check for sure, as the panel is not obviously removable. Worth the risk?

Here's a pic - also, just out of curiosity, any ideas what the white cylinder bolted at top-right is? It has a live/neutral just dangling. I thought maybe it was a spare capacitor, but then I noticed the black wire connecting up to the thermostat area. Ballast for an optional fluoro? I'll leave it well alone in any case. I'm planning to go through the drip hole for fan/heater connections, but wouldn't be totally averse to drilling straight through if that was safe.



The second question is about drilling through the top of the fridge for my thermometers. I could get extensions for them and go down the back and through the bottom, but it would be alot easier to go through the top. Again, this area doesn't appear to be directly cooled - in fact, the only area that does is the top two thirds of the back, and in the image below you can just make out the discolouration caused by the repeated cooling in one area (the straight line about 2/3 down - its not a shadow):

[Fil]

right first of im not qualified in any way to give advice on this, other than a lil hands on experience with my own brewfridge..

It looks to me as if your fridge has a single backfitted cold radiator, so you should be fine with the top and bottom hole drilling.

to check however use a thin metal screwdriver or probe, heat whatever you use so it melts through the inner shell and gently push it through the spot you want to drill, expanded foam insulation will not present much resistance and any coolant pipes should present themselves as obstacles.

personally i wouldn't drill holes through insulation and the thin inner shell to mount external components, perhaps consider mounting on a plate which you can then epoxy, hot glue, cable-tie or velcro in place?

[BenB]

The white thing looks very much like a standard motor start capacitor. Is it not for the compressor motor?!!?

To be honest I always just mount and drill through the doors / lids on these things with the wires free to flex as the door opens. Much simpler as no pipes to drill / cut through. However....

re fixing the SSRs etc I'd be wary of using anything that protrudes too much inside the fridge. You could cautiously try and drill a very shallow hole then rivet through it. I'd be happier with that than a sharp ended screw. With a rivet you push it in quite a long way then when you pop the rivet it shortens in length so even if you were in contact with something when full length when it's popped it won't be an issue. With a screw you might end up with a sharp screw end pressing against a vibrating soft copper pipe... Personally I'd just roughen up the surface and epoxy a wooden panel on and then fix everything onto that with some good old screws Don't forget the compressor gets hot so you might want to over-spec the heatsink on the SSR, it's not going to be getting nice cooling air there.... You could of course just bolt the SSR with heatsink to the floor of the fridge next to the compressor so it's getting cooler air- they've even drilled some nice mounting holes for you...

[BenB]

... or just drill a couple of mounting holes through the thin metal chassis of the fridge under the capacitor and mount the SSR there....

[vacant]

• turn fridge on
• leave door open
• come back after 10 minutes
• feel where cold bits are
• don't drill there

i.e. bottom shelf should be OK. Like BenB I think doors are a good bet. I have my gas and beer lines passing through a gap cut in the rubber door seal.
Are there any holes for thermostat/door light cables you could repurpose?

[Brewedout]

Why not take the thermometer wires through the drainage hole? Alternatively go straight down through the horizontal shelf above the compressor. Screw a cable gland in the plastic above to seal the fridge from outside air and it keeps the thermometer probe looking tidy too.

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[Matt in Birdham]

Thanks guys - all good advice. I had a good feel when on, and then went for it with a hole through the top for my temp probes and another through the upright of the compressor hump. I seem to have got lucky as everything is still working (for now). I do like the rivet idea though, Ben - might do that (haven't mounted the SSRs yet).

[Matt in Birdham]

Here's what I did in the end. I found an old alu project box lid to use as a mount for the SSRs (grooved on the other side as well, so a half decent heat sink), mounted SSRs with screws and a bit of thermal paste and cable tied the WAGO connectors on. They are not attached, but fairly secure so I just cable tied the whole lot to the strut that goes across the bottom of the fridge:



I really didn't want to go through the door seal any more, so I risked a hole through the top and got away with it - found a handy grommet as well. Should have gone nearer the back, ended up having to put a little cable support further back to hold up the fridge sensor:



Switched to a 240v AC fan so that I could run it straight off the same power as the fridge/heater (i.e. one plug to the whole lot). This seems to be working well after a few days use, at least. Also drilled another hole through the upright at the bottom for the heater cable, as it was rather thick and I couldn't get both fan + heater through the drain. Shelf is temporary hack, hope to get something metal and little more slimline one day but it does the job (old ikea table + scrap wood):



A fair bit of farting around with Brewpi parameters over the last week, but seem to be getting some fairly decent results now. Looking forward to brewing with it in a couple of weeks..