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Thread: changing orfice
02-11-2008, 01:19 AM #14
02-11-2008, 01:22 AM #15
02-11-2008, 06:04 PM #16
Since the 13 SEER condenser typically runs a much lower head presssure than the old condenser, you'd have to increase the piston size in order to get the same rate of refrigerant flow as before.
Carrier allows matching 13 SEER condensers to preexisting piston metered coils. They provided dealers with a piston selection chart for that purpose.
If you don't have something from the condenser manufucturer that tells you what size indoor piston to use, then a TXV is the best option. Also, depending upon the situation, it can be as cost effective or more cost effective to simply replace the coil. I won't say that coil replacement is absolutely necessary, because it isn't, unless your local or state codes require it.
If replacing the piston is the only option given you, then the correct piston size can be found by trial and error. The correct piston is the one that provides the recommended subcooling for the condenser, and simultaneously provides a superheat value that corresponds to a standard superheat charging chart. Perfection isn't going to happen, it just needs to be in that ballpark as close as possible.
Piston sizes marked on evaporator coil cases or in evaporator coil literature are immaterial, these are usually just telling you what piston the coil shipped with. But the piston must match the condenser, and should be resized accordingly for liquid line diameter, length, and rise. Indoor air volume should also be checked beforehand.
A successful upgrade to a 13 SEER condenser on an old evap coil isn't out of the question, but it can take a bit of doing sometimes even when you know how to go about it.
IMO, this should never be attempted on a heat pump system, straight cool only.
Last edited by hvacrmedic; 02-11-2008 at 07:44 PM.
02-11-2008, 06:12 PM #17
02-11-2008, 06:14 PM #18
I'd be concerned about liquid reaching the compressor. Can the evaporator boil off all the excess refrigerant when you upsize the orfice? You might want to ask the apartmentment manager this question. I'm sure he'll know what you're talking about.
02-11-2008, 06:20 PM #19
02-11-2008, 07:45 PM #20Professional Member
- Join Date
- Dec 2007
Find Another Co To Work For. Poor Customer Satisfaction!