Collyn Rivers looks at simple ways to improve the performance of fridges in caravans—particularly important when they’re running off batteries.
The energy use and cooling performance of fridges installed in caravans and motor homes is related more to installation than technical differences between the fridges. Few are fitted as makers advise, leading to increased energy draw and hence cost; this also applies to domestic fridges, many of which are enclosed on three sides and inadequately ventilated.
Fridges are simply boxes from which heat is removed from inside the cabinet and dumped outside. It is vital this dumped heat is removed effectively. Owners, many builders, carpenters and even some electricians perceive fridges as ‘back to front’ ovens that generate cold. This approach often leads to ventilation being ignored, resulting in poor installation—the bane of fridge makers.
All fridges require adequate ventilation spaces at their rear. However, that alone is not enough. Cool air must be routed to flow unhindered over the cooling coils (also called fins) and the heated rising air must be routed to where it cannot heat the fridge again. With caravans, this is outside the van, and for homes, it is also preferably outside. This is often poorly done in RVs, and all but ignored for self-installed domestic fridges.
Most caravan/motor-home fridges have rear-coil cooling. For this to work, cool air at the fridge base must be directed to flow over the coils. This is assisted by baffles (flat plates inserted into the airflow to change its direction and make it more effective); even baffles made from cardboard will work well. A high exit for the warmed air provides enough suction to draw in cool air.
With such fridges, adding more insulation on their sides, top and (if feasible) to the door also helps hugely. Even 100 mm is not overkill.
Some caravan and domestic fridges dissipate heat from their outer skin; these fridges have an enclosed back without cooling coils. These need a 50 mm side gap and ideally the top area should be vented to the outside. Cool air needs to be directed to the base of their sides, and back if it is used for heat dissipation (you can tell which sides are used for heat dissipation as they will get warm when running). Obviously, you must not insulate the sides and/or back of this type of fridge!
Chest fridges need provision for cool air entry, and ideally nothing located above them to roof or domestic ceiling height. Some have a fan that draws cool air in via vents in their sides and over the compressor’s associated cooling fins.
Chest fridges with coil cooling are aided by adding insulation. However, a few (such as the Indel and Ozefridge) dissipate heat from their side walls and so need a minimum 50 mm gap around the walls.
Collyn Rivers has published several books on solar electrical systems and caravanning. Visit Caravan and Motorhome Books.
Read the full article in ReNew 129.
This entry was posted on Wednesday, September 10th, 2014 at 9:54 pm