I have an older home on the Virginia Eastern shore. The house is heated with oil fired boiler and cast iron radiators. It has 2 zones - 1 for main home 1st and 2nd flrs, and 1 for family room and kitchen addition. The furnace is older with a newer burner assembly.

The house also has 2 AC units - 1 for 1st floor and 1 for 2nd floor. The airhandler for 2nd floor is in the attic with ductwork and registers from above. The air handler for the 1st floor is in the basement with ductwork and registers from below. The AC units are less than 10 years old and the airhandlers are in very good condition.

I am considering changing the AC unit on the 1st floor to a heat pump. The floor mounted registers should make it a better system for heating than the second floor.

Can I keep the existing air handler and evaportor coils and just change the outdoor condensing unit to a heat pump of the appropriate size?

Can I uses the exsiting refrigerant lines? Any down side to trying to keep the existing equipment?

Also can I interface the hydronic heat with the heat pump contolrs in lieu of electric resistance heat? Not sure if this would be feasible based on oil costs.

This is our second home and we keep the temp set at 50 degrees when we are not there. Temps in Va peninsula are pretty mild in winter, so I think a heat pump would be more efficient to run when we are away. We would probably switch over to the hydronic heat when we occupy the home in colder months.

Any comments or ideas on how to proceed would be appreciated!!

Your best bet is to call for 2 or more estimates for what you want to do from local HVAC companys.

Can it be done yes BUT
Units sold today are 13 SEER ands above. It is not a good idea to use the old coils that you have one your system right now. It creates many problems ESPECIALLY on a heat pump conversion.

Existing air handler would work but here again it is better to get new since it might be a big labor problem to change the indoor coil on the old units to match the new outside heat pump.

All controls can be combined or just use a 2 stage heat thermostat like the honeywell 8000 series.

The heat pump would run down to the calculated expense/max low temp setting then the boiler would fire off and heat the home if necessary during colder weather.

You need to keep that boiler available just in case of a cold snap or if the heat pump breaks.

I also recommend that you get a phone dialer system to call you or the local HVAC company if the temp falls below a preset level. This will prevent the pipes from freezing and causing damage when you are not there.

I believe this is going to cost big $$$ to do and the recover on utilitys will take a very long time so from a savings point of view in your lifetime forget it. Just telling it like it is. The phone dialer I would do no matter what if you have feeezing weather there. My second home has a dialer and it has saved me on more than one occasion .