Maybe this will keep my fridge cool?

[austinado16]

Just installed Reflectix over the original thin fiberglass batt insulation.  I also painted the fridge coils black to have them dissapate heat better.  I'll update once it's back together and has run for a couple of days.

[brainpause]

Hmmmmmmmm.....

Won't black paint make the coils absorb heat?

Larry

[austinado16]

Hmmmmmmmm.....

Won't black paint make the coils absorb heat?

Larry

No, black radiates heat, hence why wood burning stoves, and alot of air cooled engines are black.  Also, look at the coils on the back of a modern fridge....black. Car radiators and A/C condensors.....black.

[mike4947]

They also use special heat conductive paint. Just spraying anything with regular off the shelf black paint does insulate rather than promote heat transfer.
Back in the day when it was more economical/possible to repair auto radiators than replace them I can remember the radiator shop guys bitching about morons that would spray paint radiators and them wonder why they didn't cool as well.

[austinado16]

They also use special heat conductive paint. Just spraying anything with regular off the shelf black paint does insulate rather than promote heat transfer.
Back in the day when it was more economical/possible to repair auto radiators than replace them I can remember the radiator shop guys bitching about morons that would spray paint radiators and them wonder why they didn't cool as well.

Well, being one of those morons who's repainted a lot of radiators black and never once had a problem with overheating, even in the vintage stuff that I regularly restore, I have to say.............never had a problem with it.

While I understand the theory that coating bare metal would at some miniskewl level "insulate" it; but how much insulative or heat transfer blockage do you think you get from a layer of paint bonded directly to the surface that's maybe .0001" thick?

Sometimes theorey gives way to real life.

[AustinBoston]

While I understand that theory that coating a bare metal would at some miniskewl level "insulate" it; how much insulative or heat transfer blockage do you think you get from a layer of paint bonded directly to the surface that's mayb .0001" thick?

I wouldn't be surprised (talking strictly auto radiators) if the real problem was putting enough paint on to significantly reduce airflow, which could cause huge cooling problems.

Austin

[austinado16]

Fired up the fridge at 8pm last night.  Digital fridge thermometer was reading 72*F inside the fridge.  About an hour later, it was reading 42*F.  This morning, with a low of 57*F on the outside digital, the fridge had cooled down to 33*F and change.  Right now it 85*F outside in the shade on the digital, and the fridge is holding steady at 34*F and change.

We'll see how the temp progresses as the afternoon wears on.  It's 12 noon right now.  Also, I'm not using the cube fan inside the fridge.  I just wanted to see what the fridge would do on it's own.

Of course this isn't a super accurate test because I'm not at any sort of elevation (if that makes a difference) and I'm not opening the door every once in a while to get something out.

[AustinBoston]

Also, I'm not using the cube fan inside the fridge.  I just wanted to see what the fridge would do on it's own.

My understanding with the fan in the fridge wasn't to make the fridge colder, but to make the cold more even.  I can easily believe that in a prked pop-up with the fridge door closed all the time that it could get to 33

[austinado16]

I guess with the cube fan, I'm also thinking that there's some cooling enhancement due to the fan moving air across the evaporator fins.

Okay:  2pm.  Outside air temp in the shade, 87*F.  Inside the PUP it's 101*F.  Inside the fridge, 40*F.  (The digital fridge temp sensor is mounted mid-way deep, and mid-way up, the fridge wall inside)

I guess this is where the little fan on the condensor fins would start to be a benefit.  My fridge's louvered panels are in the shade.

I'm going to fire up the cube fan inside and see if that does anything or not at this point.

[austinado16]

Opened the fridge a couple times very briefly. 6pm now, cube fan running for about 3-4hrs, 76*F outside and 45.5*F inside the fridge.

I'm going to let it run all night and see where it's at in the morning and what it does tomorrow.

This has been the pattern during camping as well, so obviously my insulation and black paint did nothing.  It's always nice and cold after the first night of pre-cooling and then slowly creeps up during the next several days of camping.

Maybe tomorrow's test will be how it performs with a little fan moving heat through the exterior coils and condensor fins.

[skamper75]

Have you tried a small box fan blowing over the coils on the back of the fridge?  I used one out of an old pc until we got a new and larger fridge.  It seemed to cool the fridge down faster, but I didnt have a prob of it getting warmer after running.

[austinado16]

Have you tried a small box fan blowing over the coils on the back of the fridge?

No, not yet.  That's what I'm going to test out tomorrow.  I wanted to take it sort of one mod at a time in order to see what helped and what didn't.  I had to take the fridge out to switch which way the door opened (it was on wrong for some reason), so I figured I'd do the insulation and black paint trick first and test it out, before doing the external fan.

Just went out to check temps.  It's 7:30pm,  69*F outside and the fridge has dropped a full 5 degrees to 40.5*F in 1-1/2hrs.

I think the fan may be the solution since the fridge's temp is so effected by outside air temp.

[AustinBoston]

It's always nice and cold after the first night of pre-cooling and then slowly creeps up during the next several days of camping.

By chance, do you live where it is very humid?  This sounds like what I would expect if the fins in the fridge were becoming coated with frost.

Austin

[austinado16]

I'm about 10mi from the Pacific Ocean as the crow flies, with a low set of hills that seperate our weather from the coastal weather.  I think my humidity gauges on the digital weather station are typically reading around 45%.

But yes, you're right, the fins and main cooling tube under the little ice cube box do get very frosty.  I was thinking last time we were camping, "I wonder if I should either get that frost build up off of there."  The other part of this whole fridge performance equation has been that we've only been on 2 camping trips and each time we've left the "normal" weather here and travelled umpteen hours in 100+*F weather and then been at 7,000' and 85-95*F days.

I need to go camp locally for a couple of days and see what it does for real in our weather at basically sea level.

But back to the frost question: With the door switched to swing open from the correct side, I've paid good attention to how the door seal closes and even spent some time yesterday going over the seal itself with some good cleaner because it was all nasty down in the folds at the bottom.  Seems like it's closing tight all the way around though.

9:30pm, 62*F outside, 35.2*F in the fridge.  Actually, just a small amount of frost on the center cooling tube and fins in each side.  Not too bad really.

[zamboni]

No, black radiates heat, hence why wood burning stoves, and alot of air cooled engines are black.  Also, look at the coils on the back of a modern fridge....black.

That is because all of the coils you mention are not exposed to sunlight.  Black absorbs heat.  Being black does not make it radiate heat any better than being white, grey, blue or purple.  Being black makes all of your examples merely LOOK better than a colored device.

Thus, if your new fridge coils never see daylight, then black will not help them, and they will look "cool".

But, if your coils see daylight, you want them to be as non-absorbing as possible - so, silver or white.