Over cooling a Norcold Refer

Glad you enjoyed the link

Just finished installing an adjustable Ebay $3.00 Buck Converter in my N611 today - I can now adjust the voltage for the lower mounted blower motors from off evenly up to battery voltage - nice to be able to reduce noise and air flow when not needed. Send Paul at ARPrv a email he answers very quickly if your interested in knowing the cooling fin data on most any of the ARP frig's

KJINTF wrote:
Suggest you check out
arprv.com
Many excellent suggestions and lots of good reading

Thanks for the link. I watched all the videos and they were informative. What I got out of them is that the boiler temps should not exceed 350 F. Could not find data on the cooling tube temps or the fin temps, these are easier to get to with an IR gun to measure. I guess I should not expect too much with marginal temps over 90 F outside, the refer is 18 years old and it is an absorption refrigerator.

Gjac wrote:
This was my thinking also turbulent air flow cools much better than laminar air flow that is why I put the fan at the bottom.

Except it doesn't... turbulent air is much less efficient at cooling a heat exchanger. Laminar flow across the surface of the fins will be much more efficient than turbulent air.

During the summer I shot the cooling tubes with an IR gun and got about 120 deg F with 80 deg ambient. There must be an optimal range for the cooling tubes, was hoping someone would know.

The greater the temperature differential between the fins and the ambient air, the more heat the system can reject to the ambient air. There is no ideal number, it simply increases the heat transfer efficiency with greater delta-t. Obviously if the ambient air is very close to the fridge coil temp (think Arizona desert in the summer), there won't be as much heat absorbed by the ambient air as when it's a cool fall day in northern Michigan.

Gjac wrote:

wolfe10 wrote:
Total speculation, but I know reasonable air flow from the top, exhausting provides good air flow/linear air flow and assists cooling.

I would be concerned that a fan from the bottom, particularly a high CFM one could create as much turbulence and help. Said another way, it could over-cool the boiler and create turbulence at the top where the condenser is.

. This was my thinking also turbulent air flow cools much better than laminar air flow that is why I put the fan at the bottom. During the summer I shot the cooling tubes with an IR gun and got about 120 deg F with 80 deg ambient. There must be an optimal range for the cooling tubes, was hoping someone would know.

As mentioned, “pressurizing” the rear cavity from the bottom can create all kinds of cooling issues, including dead spots thanks to the turbulence, that’s why it’s rare to find any electronic equipment, especially servers with air being forced IN without internal ducting. You don’t need a turbine, just move enough air to release the heat.

wolfe10 wrote:
Total speculation, but I know reasonable air flow from the top, exhausting provides good air flow/linear air flow and assists cooling.

I would be concerned that a fan from the bottom, particularly a high CFM one could create as much turbulence and help. Said another way, it could over-cool the boiler and create turbulence at the top where the condenser is.

. This was my thinking also turbulent air flow cools much better than laminar air flow that is why I put the fan at the bottom. During the summer I shot the cooling tubes with an IR gun and got about 120 deg F with 80 deg ambient. There must be an optimal range for the cooling tubes, was hoping someone would know.

Chris Bryant wrote:
I do not believe it is a matter of over cooling anything, but rather over pressurizing the rear- the seal between the cooling unit and cabinet could be bad, as well as forcing air in the drain tube.

. Drain tube is protected inside the evaporator pan so I don't think air is being forced into that. Drain tube also has a crimped end with very small drain hole. Visually from the back and looking down the vent I didn't see any gaps.

I do not believe it is a matter of over cooling anything, but rather over pressurizing the rear- the seal between the cooling unit and cabinet could be bad, as well as forcing air in the drain tube.

Total speculation, but I know reasonable air flow from the top, exhausting provides good air flow/linear air flow and assists cooling.

I would be concerned that a fan from the bottom, particularly a high CFM one could create as much turbulence and help. Said another way, it could over-cool the boiler and create turbulence at the top where the condenser is.

Yes, the fridge cabinet that the fridge slides into.

You could even put the fan(s) on their own 12v thermostat, set to say 85F/30C.

12v digital T

jrnymn7 wrote:
Gjac said,

"I also added a curved baffle at the top exhaust area to remove the dead airspace"

... that was going to be my next suggestion.

What are the ambient and cabinet temps?

I think it's best, and easiest, to deal with the cabinet temps, and leave the fridge to work as it was designed to, i.e; not trying to cool the tubes themselves.

. What do you mean by cabinet temps? The backside of the refer?