captain

what is mdl of existing furnace? conventional blower motor or vs blower motor? it is always best to have a "matched" HP condenser and evap coil. and if you stick with Carrier, you definitely want the tin plated evap coil.

IMO

No.

The newer coils are larger than the old 10 SEER coils. If you keep the old indoor coil and connect it to a new 13 SEER condenser, you will get less than 10 SEER efficiency and reduced btu performance. Because it is a heat pump, refrigerant charge is critical and it will not be correct with a mismatched coil (even if a TXV is used at the indoor coil). This has been discussed often at www.HVAC-Talk.com.

The indoor coil must be a certified ARI (American Refrigeration Institute) match with the condenser unit to achieve rated SEER/EER/HSPF and btu output.

Good luck.

(Happy New Year TD)

It sounds like you are wanting to do a dual fuel system, but if you keep that evaporator coil, not only will the system not run at the 13 seer rating, but you will have problems with the refrigerant charge. Because the 10 Seer evap. coil is smaller than the 13 Seer evap. coil, you will end up having to take refrigerant out in the winter and add it back during the summer. Every time I go to a call where a company has mismatched the equipment like that on a heat pump, the high/ head pressure switch has tripped because the coil inside is too small and not enough air can get across that 10 seer coil with a smaller surface area than the 13 Seer.

That evaporator coil is really not that expensive compared to the outdoor unit. The evap. coil will probably be about 25% of the cost on a total job with a heat pump and dual fuel controls set up.

Good Luck

Need to replace the coil too, especially if using the new refrigerant. As said above the coil cost is not large in comparison to the complete installation.