What i've found is the colder it is outside, obviously I have to build a fire more often. In the shoulder season the boiler room stays above freezing, on one fire every two or three days. But my house is not super insulated. R-19 walls and R30 ceilings, so my house calls for heat pretty often. I always figured if i needed xtra heat in the boiler room I would run a small pex line thru my PVC conduit from house to boiler room. Put in a radiator of some sort with a TRV for control. Hook that little rad right into the house system. Even if i was off line with the wood boiler for a long time in the winter, the oil system would keep that warm.