Yes, discuss with a Contractor your question, hopefully it would be a matched system for optimal performance. If you have a piston metering device you may or may not have to change it. If you have a TEV/TXV you would have to change it to a Heat Pump rated Duty or it may already be rated for HP duty. You would have to install a bi flow drier and remove the one way drier. If the new outdoor unit has a drier in there already, then you would have to remove the existing one way drier if you have one.

Your thermostat may need to be replaced if not rated for HP duty.

You also may have to run extra low voltage wire from the indoor unit to the outdoor unit, and even the T-Stat if you use hard wire.

May need to elevate outdoor unit a few inches off the ground for the water to drain more freely after coming out of defrost.



You can operate the HP above a certain OD temperature then have it switch automatically to furnace when the OD temperature goes below the balance point.

Warranty of OD unit may be cut in half as your only replacing the outdoor unit instead of both matching pieces.

Your better off having the Contractor replacing both indoor coil and OD unit thou, at the very least of getting the full manufacture warranty.

The supply air temperature with a HP will be much lower than your gas/oil furnace ( if that is the type of furnace you have )

Your indoor coil should be rated for HP duty.

 

Depends on what you have inside.

 

As Joey said, you will be fine. If you spend the money on the heat pump, do all that has been said above.

 

Thanks guys, kinda what I thought. Im a GC, my goto HVAC guy told me it cant be done, I was surprised. I'll need to find out why, may just be cost and practicality? Maybe it's just best to replace everything? My thinking is the furnace efficiency becomes far less interesting once the furnace is primarily an air handler.
I'm in Northern California, on the border of CA climate zones 3 and 12, so heating and cooling days are pretty well even, but... we rarely run the AC. I would imagine I can run my old furnace for ever, replace the motor when and if? FAU is only 6 or 7 years old so should have lots of years left in it. I'm inclined to add solar to the house, thus the interest in electric heat. I suppose another alternative is a dual fuel combined Hydronic radiant system?
Would I want to add MERV11 (or higher?) if I do the herat pump? Wife complains of dust in the house so I wouldn't mind that anyway.
I'd assume we have a TXV, I think CEC sort of require one the past ten years or so?
Just out of curiosity, is it worth considering a pair of mini splits? house is 1800 Sq Ft, I could create sleeping and living zones, just leave the existing system alone for backup on those few cold days?
So much knowledge to be had, so little room in my tired old brain

 

It would not be hard to slide out existing A coil and install a new HP ready one whether it's a cased or uncased coil IMO ( assuming you have a coil directly tied downstream of the furnace whether horizontal/vertical ) At least it would be matched. I would not go any higher than a OD unit rated for up to 15 SEER such as a 14 SEER that say up to 15 SEER as anything higher than that the furnace comes into play to get the 16 + SEER. Even trying to get 15 SEER may not be possible with your existing furnace.

Maybe your HVAC Contractor said it could not be done due to configuration of furnace? Downflow as an example.

At least you don't have to worry about registering the equiptment in order to get the maximum manufacturer as registration is not required in Quebec and California....

The rest of your questions someone here can help you.

 

My son built additions on both ends of his house and put ductless systems in both additions. BTW, one end is the master bedroom, the other end is a large kitchen with 12' walls and a vaulted ceiling plus half a level up is a family room that is 24'x24'. He said the heat pump for the old house in between the additions rarely runs.

 

Some heat pumps, especially higher efficiencies require an ECM blower or a variable speed blower to produce their rated efficiency. You probably can swap a heat pump for your condenser but a matching indoor coil will serve you best.

 

TY Dean and Joey - I suppose operating efficiency is less critical on solar? I'll have to compare panel costs to HVAC equipment costs to see which nets out cheaper.
No surprise the middle of the house needs little heat, it's indirectly conditioned by the adjacent spaces AND has less exterior surface per CF of conditioned volume.
I suppose it would be interesting to model my house with dual fuel domestic hot ( I already have a gas tankless) vs dual fuel radiant, vs dual fuel combined hydronic vs dual fuel 14SEER HP on existing vs 16+ SEER HP on new interior equipment.
It will take me some time just to list all the options and variables lol.