Refer fans for improved cooling...what are the best options?

Suggest you use both types of fans. The ext. fan shd be both thermo and switch controlled. I would use the type fan that is moveing the most air at the slowest speed. Noise is also a factor to consider.

I use two computer fans out side ,both move about 75cfm each ,my exhaust for the frig is on the side of the rv.

I have two 92mm DELTA server fans (24 watts each!) I can't get at the top of the coil, or rather, I don't want to pull the fridge so I can get in there.

My plan is to mount them inside the top vent "hole", facing out the grill. Hot air pours out of that hole, so fans should help it along.

They'll be thermostatically speed controlled, and have an on/off switch.

So far, it's been so cold here in Michigan, the fridge barely has to run! :(

Moved from Technology Forum

I would suggest that before you go messing with fans you should insure the refrigerator is installed correctly. Your manual will have very explicit directions about spacing and clearances, these directions are often ignored by the RV manufacturer.

Sometimes adding baffles or closing off a dead air space above the refrigerator is all that is needed to optimize function.

I, too, thought about the fans used to push air out the side vent, but....
My research on the subject indicates that the air should be moved up and out of the roof vent. Fans installed so that they move/push air upwards. Heat rises so this makes sense.

Thoughts?

Baja Man wrote:
I, too, thought about the fans used to push air out the side vent, but....
My research on the subject indicates that the air should be moved up and out of the roof vent. Fans installed so that they move/push air upwards. Heat rises so this makes sense.

Thoughts?

Not all installs use a roof vent. My fridge has two side vents. I'm sure some hot air is able to bypass the upper vent and accumulate above the ceiling.

Fans vary widely in how much air they move for noise made and current sconsumed.

I like the variable speed fans for all these reasons.

While speed control can be added to any fan I like the Silverstone fm121 for the dual ball bearings and the provided speed controller whose potentiometer one can mount remotely.

The fm121 cam move 110CFM at highest speed and as low as 32CFM very quietly.

Larger computer fans can move a lot more air for even less noise.

The silverstone AP182 moves ~70 CFM for only 0.05 amps on lowest speed, and on highest speed is good for a concentrated 170CFM, but this fan does not like highest speeds and battery charging voltages, the hub will get stinky plastic hot.

Noctua make some very good fans and have 'industrial' versions of their fans which spin a bit faster and are rated against dust and moisture ingress.

I am not sure how much an absorption fridge benefits from huge volumes of air moved by a fan, compared to much lesser volumes as I use a compressor fridge.

I use the Noctua NF-f12 120Mm fan on its condenser pushing air, and fridge duty cycle improved instantly. The noctua fan being ~53CFM and the provided fan being 72CFM. The pushing of air through the resistance of the condenser and the Noctuas design allow better heat removal and shorter run times than the original fan sucking air through condenser. Also the Noctua draws only 0.05 amps compared to the 0.12 amps of the provided fan.

There are many hundreds of computer fans available in all different sizes and rpm ranges. Noctua is pretty much top of the line in my opinion, but they do not offer the blazing RPMS available from fans like Delta.

I have one 120Mm delta fan which is ridiculously powerful at 252CFM and at about 50 watts, but it cannot be slowed below about 35 watts via PWM or voltage control, or it just shuts down. Much too loud and powerful for normal use, and its impeller will easily chop off a fingertip.

landyacht318 wrote:

I have one 120Mm delta fan which is ridiculously powerful at 252CFM and at about 50 watts, but it cannot be slowed below about 35 watts via PWM or voltage control, or it just shuts down. Much too loud and powerful for normal use, and its impeller will easily chop off a fingertip.

Nidec and Delta both make some awesome fans.

If you're ever in the market for a do-over on a speed controlled fan, the 4-pin "PWM" type are very easy to drive with a microcontroller or 555 timer circuit. You don't chop the supply voltage, as that messes up the brushless controller.

The 4th wire is a pwm input (3rd wire being a hall-effect switch open-drain for tachometer). You feed it a ~100hz pwm signal to vary the speed, or connect it to ground for minimum speed. The brushless controller will sync with the pwm input and resist stalling, vs pwm of the main dc input.

beemerphile1 wrote:
I would suggest that before you go messing with fans you should insure the refrigerator is installed correctly. Your manual will have very explicit directions about spacing and clearances, these directions are often ignored by the RV manufacturer.

Sometimes adding baffles or closing off a dead air space above the refrigerator is all that is needed to optimize function.

beemer....

I agree with the installation info. I reviewed the install manual and it states that there should be 1" max space behind refer. This is basically almost kissing the coils.

My space is more like 6". I'm sure this added space has the effect of more hot air hanging around coils, which means longer times for air to rise and exit roof vent and also equals more hot air warming coils.

Less space means less hot air around coils, air rises quicker as there is less of it, and ultimately cooler coil.

Is this logic about right?

Also, can I decrease the space down to 1" without removing the refer?

If so, how? Can I glue blocks foam against RV sidewall until I reach the 1" gap between the new wall of foam and refer?

Thoughts?