Old 01-13-2008, 05:31 AM
Senior MemberCaptains Club Member
Join Date: Jan 2002
Location: Theodore Al
Posts: 116
Default RE: Mis-matching HVAC system (replacing outside unit without touching inside)

You can replace the outdoor unit without replacing the indoor, but as they said it is not recommended and
most companies will not do it. Here in Alabama you could not get it permitted or inspected. The problem is
not the heater but the cooling coil, but it is probably a single unit and not a separate heater and coil.
The new units have thermostatic expansion valves on the indoor coils as opposed to a fixed orifice on
the older units. This helps to obtain the efficiency for the unit and also keeps the correct superheat to
the compressor which lets it live a long time. One of the dangers of not replacing the coil is that the
superheat is not correct and refrigerant floods back to the compressor which can damage or destroy
it. Then you have the issue of R-22 being fazed out, and replaced with r-410A or Puron as carrier calls
it. If you replace the indoor equipment you may consider going with the new refrigerant. I would say
replace the compressor if the rest of the outdoor unit is in good shape, or go ahead and replace
everything with the new refrigerant. They will also have to replace the line set again if you go with
the new refrigerant. The oils are not compatible. But I have heard of companies doing it without
replacing the lines, just flushing them out. I hope this helps.
N D H is offline