back up heat question -- again.
I'm still trying to get a handle on the best way to replace the heating systems on my fire damaged house -- I have asked questions before on this project and others and I appreciate the input. The house is a small converted church with a smaller attached wood building - all about 4k square feet. Previous two oil furnaces --- one 80k and the other 120k with AC. Both structures were spray foamed and will be after the retrofit. The wood structure needs to be demolished and this is where both units lived - basically a big kitchen with mudroom and utility room under it. I don't have natural gas and no one recommends putting oil back --- and with electric going for > .18 kilowatt in SE PA it looks like heat pumps and Propane with the units now separated into the respective buildings. I just learned from this forum that HP's don't like indoor temps bellow 60! I currently don't live permanently at this house and we normally set the temp to 58 when we leave -- often for over a week. With the oil units and oil HW -- we had a toasty house in less than an hour after we got there. So how fast does a HP heat from 60?
I still don't know how best to do the back-up heat. I like the idea and simplicity of having two propane Carrier Infinity furnace HPs for the heat modulation vs a boiler and two fan coils --- but ... I think my logic may be wrong. Since the HP's will be working most of the time .....when I need the back-up (propane) on cold days or when I first get to the house -- I'm not going to be needing the modulation of the furnace anyway. So what is the need for an expensive modulating furnace when you have a heat pump?
The house still may have a boiler: I'm thinking possible supplemental radiant heat in some open areas (kitchen/ bath floor) and heating an outbuilding about 20' away currently heated with one electric 20 amp 240 wall heater and 30k btu forced air wall mount forced air propane rather then installing a separate new unit in that building for a new radiant floor - plus I could do my domestic hot water. This fire has created opportunities to do some things that I would never have been able to do and I only have one shot at it -- like the possible radiant floors. I'm never going to be selling this place. Do you think trying to pump hot water 20' through insulated pipe is crazy? I have a neighbor doing it and it seems to work and you see this with wood boilers -- don't know the energy loss.
Any thoughts would be helpful -- it is difficult to get information as most local HVAC contractors don't often do this kind of complex system and I think most are afraid to do anything other than install basic systems.