I presume the colder a fridge or freezer is the more efficiently it runs right.

Has anyone ever thought of creating a special ventilation void behind a fridge that either ventilates passively to the outside or hooks into mechanical ventilation system with heat recovery?

Many domestic fridges and freezers may work *less* effectively or even be damaged AFAIK if the ambient temperature is much cooler than a typical indoors temperature, eg due to the nature of the working fluids which may become too viscous at low temperatures.

You'd have to read the operating manual or tech specs.

Rgds

Damon

Posted By: DamonHDMany domestic fridges and freezers may work *less* effectively or even be damaged AFAIK if the ambient temperature is much cooler than a typical indoors temperature, eg due to the nature of the working fluids which may become too viscous at low temperatures.

You'd have to read the operating manual or tech specs.

I wondered whether this might be the case.

There are also many, many, fridges and freezers that work just fine when outside. Like many thousands of others across the country, I've had a chest freezer in the garage for decades. The current model uses exactly the same refrigerant (R134a, or tetraflouroethane) as large numbers of modern fridges and this, like virtually all refrigerants in common use, doesn't "get too viscous" over the range of temperatures likely to be experienced outside, or in an unheated room, in the UK (if you've "seen" the stuff you'll see why!).

The newer refrigerants, like R410A, are equally unaffected, as the boiling and freezing points show (-48 deg C and -155 deg C respectively.) A fridge condenser will always be a few degrees above ambient, as it will be transferring heat, so will always be operating at well over the boiling point of the refrigerant.

Cold rooms and refrigerated trucks bear witness to this fitness for use in cold outside conditions, they have their condenser units, or even the entire pump/condenser unit, out in the open and work just fine and they use the same range of refrigerants used in domestic appliances.

It's true that moving refrigerators or freezers can cause them to stop working for a while. The cause is two fold, either liquefied refrigerant getting where it shouldn't, into the "wrong" side of the system as a result of the fridge being tipped up to move it, or oil from the compressor getting into the narrow bore pipework for the same reason. The cure is to follow the instructions from most (all?) manufacturers and leave the fridge unplugged in it's new location for a few hours for everything to settle and drain back before turning the power back on.

Generally, allowing cool air to circulate around a fridge will improve the efficiency slightly, although, as discussed on another thread here, adding extra insulation around the cabinet may give better results. If it were me then I'd design an insulated box in an outside wall into which the fridge fits tightly, and then have a couple of external vents to allow cool outside air to circulate over the condenser.

JSH: I was objecting to the "presume" without looking at the specs of the appliance. It's good to know that it often won't be a problem, but presuming seems unwise nonetheless.

Rgds

Damon

If you're having weather that requires heating the house then venting the fridge to outside will waste heat that would otherwise be helpful.

If you're not in a heating weather regime then venting to outside won't help much, if at all, and is quite likely more hassle than it's worth.

<blockquote><cite>Posted By: Ed Davies</cite>If you're having weather that requires heating the house then venting the fridge to outside will waste heat that would otherwise be helpful.</blockquote>

True.

<blockquote><cite>Posted By: Ed Davies</cite>If you're not in a heating weather regime then venting to outside won't help much, if at all, and is quite likely more hassle than it's worth.</blockquote>

Not necessarily. The fridge COP will improve as the temperature at the condenser drops, so as long as the outside air cooling the condenser is lower than room temperature then the fridge COP will be better, so the fridge will use less energy. As long as the vents can supply air that's cooler than the room temperature, which is likely to be the case for the majority of the non-heating season (assuming a well-insulated house).

The hassle factor depends on whether it's a retro fit to an existing building, or a new build. There's little hassle or additional cost from building in cool air ducting to a new build, or adding heat recovery for use in winter, come to that.

One major issue is that the trend for built-in fridges and freezers is creating efficiency problems and energy wastage in many cases. We stayed in a holiday let recently with built-in appliances, and the temperature of the air coming from the (small) vents for the fridge and freezer was surprisingly high, far higher than that at the rear of our free standing fridge. There has to be merit in looking to reduce that temperature and make use of the waste heat.

Posted By: Shevek

Posted By: Ed DaviesIf you're having weather that requires heating the house then venting the fridge to outside will waste heat that would otherwise be helpful.

Unless you vent it via heat recovery.

By a strange and magical coincidence, the quantity of heat available at the back of the fridge is almost the same as the quantity of heat needed to reheat the room because of the heat that has leaked from the room into the fridge (think about it). So piping that heat away just increases the heat you need to supply.

Edit deleted as found a more suitable thread on my subject, sorry!

what about in summer if we get one?

The heat output from a fridge is hardly likely to overheat a house, just looking to stop wastage. Also I would guess that 99% of fridges are in houses anyway, I am just putting the "body" of the fridge in a cool envoironment so it has less work to do, Also if I put the complete fridge in the larder the heat output would raise the temp which I do not want in a larder.

When they say a 'months worth of rain in 2 hours' or similar, I hope they mean the month they are referring to, so a months of June's rain in 2 hours, rather than the wettest month.
Seems I have just mossed all this really heavy rain where I am, seems to have gone a bit further ENE and dumped on Devon
Not that I am suggesting that caravans should come down as magically all campsites are water logged.
Some historic data:

Posted By: RobLThis thread persuaded me to try putting a little 1W computer fan around the back of our fridge/freezer

I tried that with two fans, made no real difference. I think you would need to control the direction and turbulence better, or go for a bigger fan and just rely on massive bulk air movement. You also need to wire it in so that it is only on when the compressor is on.

Hi,

Is the fan wired to the motor? so as per above so only on when the motor is running.
Are you pushing warm air from around the motor over the condensor? Ideally cool air from outside, then could run over the motor through and out of front base of fridge. This would cool the condensor and move warm air into the room and prevent the motor generated warmth from drifting up onto the cold box.
Cheers, Mike up north

Posted By: RobLI left it on for 24 hours,

I think that's far too short a period of time for an experiment like this. You need to do it for a few weeks and note the temperatures in the room as you go along (e.g., record hourly) and the same for a similar length control period without the fan.

The difference between those readings is only 80 Wh which corresponds to perhaps 40 minutes run time - say two cycles. You might have just been unlucky with the exact time of starting and stopping the measurement.