Disable fan when fridge is keel cooled?

[Tim Good]

So I have an Air Cooled Frigoboat 12v fridge. It's been fan cooled for 1 year. I have just added a keel cooler and now back in the water the fan is still operational. So the fridge coolant goes through the fan matrix and then down into the keel cooler, before going off to the evaporateor plate.

Would this:

A: be better as it is double cooling and only the power of a 12v computer fan being used.
Or
B: worse as the fan won't be doing anything like what the keel cooler is achieving so best to turn the fan off and save energy + noise.

Note: it is legit to convert a fan assisted compressor to keel cooled down the line and also has the added benefit of being able to use the fridge when dried out or on the hard.

 

[Caladh]

I just put a push on/off switch on the fan connection and turn it on if necessary when the boat is out of the water. Your keel cooler should be more than efficient at cooling and doesn't need the extra fan assistance. As you point out, the coolant is getting to the keel cooler via the fan matrix anyway.

 

[superheat6k]

The cooling is of the condenser rather than the compressor, generally the compressor is cooled by the cold returning refrigerant from the evaporator. The cooling is the removal of heat at the condenser, in this case the keel cooler. I assume you have removed the original air cooled condenser, indeed I can't see how it would work properly with two condensers without very complex controls.

However, sometimes the compressor or the space it is within can get excessively hot so if this is the case then some air flow over the compressor might help. So if its a small computer fan I would suggest you see how hot the space around the compressor gets and if less than say 40oC (no fan) it is fine but > 50oC it is a bit too hot.

 

[William_H]

Superheat is right in that the actual temp observed in the compressor/ condenser compartment is what really matters.
I find it strange that you have the air cooled condenser still in circuit and even more so that it is first after the compressor.
I would have thought keel cooler first or only as this will be very efficient at getting temp of compressed gas down.
I think however that the compressor will get the hottest as this is what compresses the gas so increases it's temp. So this may benefit by fan cooling. But these are all variables so your actual working area temps are what matters. olewill

 

[Tim Good]

I'll try and do a like for like comparison of amps used over a 10 hours period at night and also monitor the compartment temp. Will report back.

 

[Caladh]

Superheat is right in that the actual temp observed in the compressor/ condenser compartment is what really matters.
I find it strange that you have the air cooled condenser still in circuit and even more so that it is first after the compressor.
I would have thought keel cooler first or only as this will be very efficient at getting temp of compressed gas down.
I think however that the compressor will get the hottest as this is what compresses the gas so increases it's temp. So this may benefit by fan cooling. But these are all variables so your actual working area temps are what matters. olewill

The compressor I bought from Penguin specifically had the ability of both air and keel cool. As indicated in my previous post, the coolant goes thru the air cooled fan assisted option (if required) first and then down to the keel cooler - and works a treat.

 

[Tim Good]

The compressor I bought from Penguin specifically had the ability of both air and keel cool. As indicated in my previous post, the coolant goes thru the air cooled fan assisted option (if required) first and then down to the keel cooler - and works a treat.

Yes so ypu have the same as me. With yours did you find you had to drop the thermostat afterwards or did you keep the thermostat the same and just saw less ampage use?

 

[Caladh]

Yes so ypu have the same as me. With yours did you find you had to drop the thermostat afterwards or did you keep the thermostat the same and just saw less ampage use?

Definitely less amps used. we are in the Med and over 24 hrs average about 2.5 - 3.5 amp per hour. Fridge is relatively well insulated.

 

[superheat6k]

If you are increasing the cooling of the condenser(s) then you are actually reducing the saturated temperature (temperature at which the refrigerant condenses into a liquid) and with it the compressor discharge pressure = less energy required to drive the compressor = less power consumed.

Be aware that the flow of refrigerant requires a suitable pressure drop across the fine capillary tube between the condenser and evaporator, so if the condensing pressure falls too much then possibly insufficient refrigerant will flow, which can reduce the cooling effect inside the fridge.