Originally Posted by Stefandmissy
"What is the harm in buying a three way, It will only afford me yet one more option and how can that be bad?" I subsequently spoke to a fellow who said that a friend of his had one and it gave him nothing but grief. Do you think that it was an isolated incident or are they inherently problematic?
3 way fridges are just 2 way fridges with an extra heating element and the controls for it. No difference in reliability. The disadvantages are:
1) purchase price, typically $100-$200 more
2) complexity of installation, since heavy cable has to be run to the batteries for the 12v
section unless it is already present.
Originally Posted by idroba
The heating element on the 12 volt side of the 3 way is generally in the range of 240 watts or it takes 20 amps at 12 volts. That is a lot. However the 120 volt heater is usually about 300 watts so you can see that in hot weather, the 12 volt element is not going to do as good a job at cooling as the 120 volt element would because of it's lower output.
In general the 12v
and 120v elements are designed to have the same wattage under actual operating conditions. How many watts this is will vary depending on the size of the fridge. The larger 8 cf and up fridges would have elements approaching 300 watts while smaller fridges typical of the OP's situation will have 100-150 watts.
The actual watts is proportional to the square of the voltage, so a 10% voltage change will lead to a 20% change (approximately) in wattage.
Usually 3 way fridges that don't cool well on 12v
are adversely affected by undersized wiring or loose connections.
I have had several 3 way refrigerators in trailers, and find them to be a solution looking for a problem to solve. Understand, like all opinions voiced here, this is mine. About 90% of my travels are with the refrigerator on propane, as I almost exclusively boondock and don't have power available to even use the 120 volt side of the refrigerator.
I agree. They have a place in boats, B vans, and truck campers, where a solid connection to the 12v supply from the alternator is more readily achieved and where there are more difficulties filling the propane tank.