Is a fridge cooling fan kit worthwhile in terms of power usage.

[WildBunch]

I have a the "jumbo" Dometic 8505 fridge freezer in my van. It does seem to use a lot of gas on hot days. It normally works quite well & have not been in a situation where the fridge does not work. But it can take several hours to cool down on initial turn on in hot weather. I am deciding if a cooling fan is necessary or not.
Once you have fitted a cooling fan kit to your fridge has anyone noticed if the fridge uses significantly less gas or 12 volt power than before.
I am going to upgrade the from lead acid to lithium shortly and only have a modest 150 Watt solar panel. I am fitting a new MPPT type solar controller which will enable me to fit a 250 Watt panel in the future (if needed). I am hoping that on sunny days the solar will be able to run the fridge & save on gas.

 

[Richard n Ann]

I've never done any tests measuring gas use but the thermostat must switch off sooner with the heat being taken away faster by the fan.
You don't have to spend lots on a kit, you just need a 120mm fan and something like this in the outside fins to switch it...

 

[Gaston aires]

We have one but I can’t say weather it saves on gas. It’s supposed to make the fridge more efficient in hot weather.
Phil

 

[cyberyacht]

You would need a lot of solar to run the fridge. Perhaps 5-600w in southern Spain in summer might do it between about 10:00 - 16:00. Not really realistic.

 

[Lenny HB]

Once you have fitted a cooling fan kit to your fridge has anyone noticed if the fridge uses significantly less gas or 12 volt power than before.

I've really checked with the external fans as the first thing I do to a new van is fit external fans as the fridge is useless without them. I too have an 8505 so did my last van.
What I have noticed that after fitting an internal fan the gas consumption is about 10% higher but a small price for cold beer.

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[Lenny HB]

I've never done any tests measuring gas use but the thermostat must switch off sooner with the heat being taken away faster by the fan.
You don't have to spend lots on a kit, you just need a 120mm fan and something like this in the outside fins to switch it...

View attachment 582243

I've done similar in caravan fridges but found them useless when you have the big fridge/freezer that are fitted to most Motorhomes. You need to be able to set the fan turn on temperature to suit the fridge installation. I like my fans to turn on when the outside temperature is 25° on my last van it meant setting van turn on temp to 34° on this van 32° obviously temp depends on where the sensor is located.

 

[Jimbohorlicks]

We have 3 computer type fans on the top vent of our fridge ,on a thermostat. Seems to improve the cooling of the fridge in hot weather and they only run on milliamps so not noticed any 12 v power loss.

 

[Littlewheels]

I've really checked with the external fans as the first thing I do to a new van is fit external fans as the fridge is useless without them. I too have an 8505 so did my last van.

We have 3 computer type fans on the top vent of our fridge ,on a thermostat. Seems to improve the cooling of the fridge in hot weather and they only run on milliamps so not noticed any 12 v power loss.

Do you have any links to your set up, l tried this last year sadly without success and blamed the kit that l chose. Thanks.

 

[Jimbohorlicks]

Mine were "home made" ,I just used 3 old computer fans I had and wired them up with a thermostat control off e bay. Had them around 4 years now with one fan replaced.
I also use a small pc fan inside the fridge if the van gets hot inside,but that just plugs in to a 12 v cig type socket as and when required .circulates the air around the fridge .
But you can buy a kit off e bay .you just have to link to a 12 v power source

 

[Richard n Ann]

I've done similar in caravan fridges but found them useless when you have the big fridge/freezer that are fitted to most Motorhomes. You need to be able to set the fan turn on temperature to suit the fridge installation. I like my fans to turn on when the outside temperature is 25° on my last van it meant setting van turn on temp to 34° on this van 32° obviously temp depends on where the sensor is located.

Yes that's how I adjust mine, by moving the sensor left or right in the fins, when the liquid line (ie condenser exit) is at ambient temperature there's no point in the fans continuing to run so it switches off

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[Two on Tour]

Our setup, along the same lines. Our fridge/freezer is the tall Dometic 8501

 

[Bessy765]

Our Dometic fridge freezer uses 17 amps @12 volt set at no,4 out of 5 temp settings. if I use it through our Victron multi inverter to run it on 240 the inverter uses 19 amps @ 12 volt to produce the required 240 volts a/c to run it. The only slight advantage is on 240 it is temperature controlled where on 12 volt d.c. it is not. For me not a problem either way as I have 700 watts of solar on the roof and 200 amps of Lithium. But there is not much point in harvesting 12 volt d.c. power to run a 240 volt A/C Appliance which can run on 12 volt d.c. ultimately is inefficient use of resources. The current used by my 2 cooling fans is nominal but in the very hot weather in 2020 south of France 35c + it had a noticeable effect on the efficiency of the fridge, as does winter covers during low temperatures. The temperature of the air passing over the rear pipes of your fridge freezer has a marked effect on the performance on it. In very hot weather actually turning the gas down lower and the use of cooling fans is better. There is a maximum temperature the chemical reaction of the mixture of gases in the system to produce the best process and very hot weather and a hot flame raise it above that, as does too lower temp in the winter.

 

[Richard n Ann]

Mine are on the van so I can remove the grille...

I also put a series/parallel swich on for fast/slow modes

 

[Chrisvh]

A very neat piece of work.
i have a kit to install but am struggling to find a 12v connection. I have a Dometic RMD 8555 fridge freezer. Has anyone connected a fan kit to this model?

 

[Bessy765]

At the rear of the fridge you will have a light wired 12 volt supply permanently live and a heavier 12 volt that supplies the 12 volt power when the engine running.

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[WildBunch]

I've really checked with the external fans as the first thing I do to a new van is fit external fans as the fridge is useless without them. I too have an 8505 so did my last van.
What I have noticed that after fitting an internal fan the gas consumption is about 10% higher but a small price for cold beer.

Hi.
The higher gas consumption with a fan fitted is surprising. Do you have an explanation as to why this is so ?

 

[MattR]

I don't know about gas use but have found that our fan helps the fridge get down to safe temperature for food storage faster and keeps the fridge from warming up much when the sun hits the side of our camper where the fridge is.

 

[Jimbohorlicks]

Hi.
The higher gas consumption with a fan fitted is surprising. Do you have an explanation as to why this is so ?

Because the fan is circulating cold air from the cooling fins to other parts of the relatively warmer fridge,thus requiring more power, ie gas.

 

[Bessy765]

I think you will. Find the reference is to cooling fans mounted outside of the fridge to direct more airflow over the external pipe work.

 

[Jimbohorlicks]

I think you will. Find the reference is to cooling fans mounted outside of the fridge to direct more airflow over the external pipe work.

No the reference from Lenny HB was to an internal fan , to cool his beer. ,post#5

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[Richard n Ann]

Hi.
The higher gas consumption with a fan fitted is surprising. Do you have an explanation as to why this is so ?

Yes, the thermostats are very similar to domestic fridges and are made to be fastened on a static evaporator. The cut out temperature range is something like -3c to -11c on maximum. If you fit a fan sucking all the internal air past it, it will never get to the cut out temperature and the fridge will run continuously.

When fitting a fan in a domestic fridge, the thermostat is changed to a VB7 bottle cooler type that has a cut out range more like -5c to +10c

 

[Lenny HB]

Hi.
The higher gas consumption with a fan fitted is surprising. Do you have an explanation as to why this is so ?

I have external fans but this is the one I'm talking about.

 

[Richard n Ann]

I like the fridge cooler in the bottom. Beers in the bottom, butter in the top

 

[TheBig1]

At the rear of the fridge you will have a light wired 12 volt supply permanently live and a heavier 12 volt that supplies the 12 volt power when the engine running.

down at the bottom of the fridge, behind the bottom vent is the 12v connection. Ground, engine running from a relay and a permanent live for the control board and light

 

[Chrisvh]

Thanks for the info. Need to fit it before heading to Spain in April.

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[Lenny HB]

I like the fridge cooler in the bottom. Beers in the bottom, butter in the top

Trouble with Dometic fridges they are always colder at the top.

 

[Jimbohorlicks]

Thanks for the info. Need to fit it before heading to Spain in April.

If you are parked up on a site you can always take the top vent off to allow more airflow.

 

[mikecambrai]

The type of fridge is so important when using them in hot climates. The only fridge likely to cool your beers at 30C will be a compressor fridge and Dometic does have a very good series of these models, but they are very expensive. Any fridge which works on the old Electrolux ammonia heating system (one that can use gas, 12v or 220) just cannot work well at high ambient temperatures. Now with a compressor fridge, adding fans to the rear of the unit passing cool air over the condenser will make the fridge more efficient at high ambient temperatures.

 

[Oisin]

Hi

Sorry if this sounds stupid..
Do you suck warm/hot air out from the rear of fridge OR blow air into the rear of fridge??
Thanks

 

[Lenny HB]

Hi

Sorry if this sounds stupid..
Do you suck warm/hot air out from the rear of fridge OR blow air into the rear of fridge??
Thanks

Suck it out you want to draw the hot air out of the top vents, also those type of fans are more efficient extracting.

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