Why does levelling the RV affect the life of the fridge?
In an absorption fridge the flow is by gravity; parked out of level, liquid ammonia collects, cooling stops and, if repeated, the unit is permanently damaged.
In absorption (ammonia) caravan refrigerators the evaporator tubes are made with a slope so that the liquid flows by gravity. If the vehicle is standing still and the fridge is run while out of level, liquid ammonia collects in sections of the evaporator tube and the cooling stops. Compressor fridges do not have this mechanism; their tolerances are markedly wider.
Why the absorption circuit is sensitive to tilt
There is no pump in an absorption cooling circuit; the flow depends entirely on gravity. That is why the evaporator pipework is made at the factory with a particular slope. When the caravan is not level that slope is upset, liquid ammonia collects in sections of the pipe and the circulation of the circuit is broken. The result is first a weakening of the cooling and, if it is repeated continuously, permanent damage to the cooling unit.
The manuals of absorption fridge manufacturers therefore ask for the fridge to be run level after the vehicle has been parked. The tolerance value varies with the model; take the value in the manual of your own appliance as the basis - it would not be right to give a single angle that holds for all. For the definition of the concept you can look at the entry on absorption refrigerator tilt tolerance.
The difference between travelling and standing
- While the vehicle is moving the sloshing keeps the flow going, so tilt causes no problem; the risk arises while standing.
- On short breaks, keeping the fridge switched off is safer than running it on sloping ground.
- If the vehicle has pulled onto a sloping verge for a long lunch break, switch the fridge off; even a few hours of running out of level affects the circuit.
- When the cooling stops the fridge does not recover at once; after it has been brought level, getting the cold back takes time, and during that time do not open the door often.
- The cooling unit contains ammonia under pressure; if you smell ammonia, switch the fridge off and go to a service agent, and do not open the circuit.
The decision by type of fridge
| Type of fridge | Sensitivity to tilt | Behaviour after parking |
|---|---|---|
| Absorption (ammonia) | High | Level first, then switch on |
| Compressor | Low | Levelling is for comfort |
| Thermoelectric | Almost none | Tilt is not a selection criterion |
If you do not know the type of your fridge, the label on the rear grille and the presence of a gas operating option will guide you: a fridge that can also run on gas is in all likelihood an absorption one.
What levelling does not solve
Tilt is not the only cause. If the ventilation grilles behind the cooling unit are blocked, or the vehicle takes the sun on that side all day, the fridge cannot cool even when it is level. As the ambient temperature rises the capacity of an absorption fridge falls; that is not a fault. Levelling will not bring back a unit that has been run at a heavy tilt for a long time and has developed a blockage inside it - beyond that point it is a job for a service agent. If the gas flame or the electric element of the fridge is not working properly the symptom is again a failure to cool; confirm that the energy source is working before arguing about tilt. In short, levelling prevents damage, it does not repair damage already done.
What to do in practice
As soon as you park, set the order like this: position the vehicle, complete the levelling, then switch the fridge on. Since a system like the KTS200 does the levelling after parking at one button and to an accuracy of 0.025 degrees, in caravans with an absorption fridge levelling is a matter of equipment life rather than comfort. The same dual axis measurement puts the grey water drainage right as well; the relation between drainage and tilt is solved in the same operation. The most frequent mistake on a campsite is to switch the fridge on as soon as the vehicle is in place and leave the levelling for later; reversing that order costs nothing, but in the long run it decides the life of the cooling unit.
The full topic: RV automatic levelling guide