OK, I have seen this on here before but I cannot find the answer. How many degrees each direction can your fridge be off and still be safe? I think it's 3 degrees one direction but I don't know which ...
Do yourself a favor and install the ARP protector and don't worry about level. The ARP pays attention to what really matters- boiler temperature. As long as the boiler has enough liquid, level doesn't matter, as the solution is circulating.