Increasing Airflow through Condenser.
The new DC only compressor fridge I will soon have in my possession has a 92 mm computer muffin fan pulling air through only a portion(~85%) of the ~120mm tall condenser. It then blows this warmed a...
Forum Discussion
I've been reading a LOT of the Kollmann marine refrigeration forum. Lots of good info. On some other boating forums he participates on are filled with nuggets of info too.
My old Norcold had a passive condenser like your link. I had a low cfm fan blowing fresh cool air up from the bottom and built a wall to restrict the flow to only around the condenser coils. The Norcold came with a fan back there but it only came on above 110 degrees.
When I saw the Danfoss compressor on my dads ~6.0 Cubic foot Tundra and the forced air condenser,I got fridge envy. I could not believe how quiet it was.
When I first got the Norcold and ran it in a hot garage in Florida in August the duty cycle was alarming at close to 70%. I designed the cabinet so that I could add extra insulation to the box. I had 1/2 inch foam board then 3/8 dead air space, then 3/8 more insulation then 1/2 inch plywood. And was able to achieve a duty cycle under 30% in conditions under 85F. So now I will have room for 1.5 more inches of insulation all around the Vitrifrigo fridge. Gonna get a sheet of 3/4 inch insualtion and put one layer on the cabinet walls and 3/4 on the fridge box and it should be a honeymoon fit. I can even fit 1/8" more behind the rattling black plastic panel on the door face. I have a large sheet of stainless steel which can be cut to fit. But the stainless probably conducts the cool from the inside better than the Plastic.
Just a while ago I shut off the fridge, climbed into the adjacent cabinet disconnected it from power, then removed the resistor. Then hooked it back up without the resistor and turned the dial to the same setting as before.
Ambients have dropped to 64 and the duty cycle has risen to 5:20 on and 12:35 off, but box temps are now at 36f
The resistor according to my Cen Tech DMM is 270 ohms which would have corresponded to a ~2500 rpm compressor speed. I will see how it does in warmer temperatures, but I believe I can also get a lower CFM fan for the condenser. So now I have gone from wanting to put a more powerful fan on the condenser and reversing the flow to contemplating putting a slower quieter less wattage fan on it.
With the extra insulation and a shroud to keep condenser air being recycled, I think I can keep the duty cycle in the 30% or under range with the slowest compressor speed.
Latest cycle was 5:23 on, 11:18 off at 37f average interior. I just backed off the dial another 15 degrees.
My old Norcold had a passive condenser like your link. I had a low cfm fan blowing fresh cool air up from the bottom and built a wall to restrict the flow to only around the condenser coils. The Norcold came with a fan back there but it only came on above 110 degrees.
When I saw the Danfoss compressor on my dads ~6.0 Cubic foot Tundra and the forced air condenser,I got fridge envy. I could not believe how quiet it was.
When I first got the Norcold and ran it in a hot garage in Florida in August the duty cycle was alarming at close to 70%. I designed the cabinet so that I could add extra insulation to the box. I had 1/2 inch foam board then 3/8 dead air space, then 3/8 more insulation then 1/2 inch plywood. And was able to achieve a duty cycle under 30% in conditions under 85F. So now I will have room for 1.5 more inches of insulation all around the Vitrifrigo fridge. Gonna get a sheet of 3/4 inch insualtion and put one layer on the cabinet walls and 3/4 on the fridge box and it should be a honeymoon fit. I can even fit 1/8" more behind the rattling black plastic panel on the door face. I have a large sheet of stainless steel which can be cut to fit. But the stainless probably conducts the cool from the inside better than the Plastic.
Just a while ago I shut off the fridge, climbed into the adjacent cabinet disconnected it from power, then removed the resistor. Then hooked it back up without the resistor and turned the dial to the same setting as before.
Ambients have dropped to 64 and the duty cycle has risen to 5:20 on and 12:35 off, but box temps are now at 36f
The resistor according to my Cen Tech DMM is 270 ohms which would have corresponded to a ~2500 rpm compressor speed. I will see how it does in warmer temperatures, but I believe I can also get a lower CFM fan for the condenser. So now I have gone from wanting to put a more powerful fan on the condenser and reversing the flow to contemplating putting a slower quieter less wattage fan on it.
With the extra insulation and a shroud to keep condenser air being recycled, I think I can keep the duty cycle in the 30% or under range with the slowest compressor speed.
Latest cycle was 5:23 on, 11:18 off at 37f average interior. I just backed off the dial another 15 degrees.
