Hey guys the question on temp for water depends first on do you have a tankless coil within your oil boiler or an indirect tank, either way the low setting on the aquastat is for domestic water temp protection.We could get into a whole conversation about controls but there is a very simple and inexpensive way to do what you are trying to accomplish without adjusting anything on your boilers and they will talk to each other to determine where the heat comes from and the temp will be constant. This can be accomplished using a simple honeywell strap on aquastat attatched to the incoming wood boiler line, the R and B terminals will break on rise and this gets wired to interupt power to B-1 on the oil boiler, by doing this the added aquastat will interupt power to the burner any time that the wood boiler is up to temp and when it is not the oil boiler will kick on with a call for heat and run up to the oil boiler aquastat setpoint, by turning down the oil boiler aquastat to say 140 during the winter months to keep the oil boiler from coming on you may need to readjust it to supply enough heat if your wood boiler goes out. If you need help with part numbers or wiring diagrams PM me with your contact info and I will try to help.
Richard @ PM