Old conderser unit replacement?

[wubsel]

Hello! My home was originally equipped with two Tappan model CM 36-41 C three ton AC condensers (1975) on its two split systems, one serving the downstairs, the other upstairs. Both are combination gas fired furnace/AC systems.

12 years ago the downstairs unit condenser gave up the ghost and was replaced by a Rheem model RAKA-042JAZ 42,000 btu 10 SEER 3 1/2 ton R-22 condenser unit. The original inside natural gas heater and A coil unit was left intact and unmodified. This combination has worked perfectly for the past 12 years and continues to do so today.

Now the 37 year old Tappan CM 36-41 C condenser for my upstairs AC/heater has finally bitten the dust (grounded compressor) and needs to be replaced. I would like to do the same thing as before and replace with a 10 SEER Rheem R-22 unit but they now have only 13 SEER R-22 condenser units. My question for you experts is would it be ok to install a new 13 SEER R-22 3 or 3 1/2 ton Condenser leaving old upstairs A coil intact as before?

[BaldLoonie]

You are lucky that the 10 SEER Rheem functioned on the old coil. At what efficiency & capacity, who knows. But you'll be less lucky that a 13 SEER dry unit will work on the antique coil since the 13 SEER runs MUCH lower head pressures than the old CM. It would have to be way overcharged in order to function which means more electric usage and strain on the compressor. New coils aren't that much money in the grand scheme of things, do it right.

[wubsel]

Thanks, baldLoonie!

I was afraid of that. Guess I'll bite the bullet and have the A-coil replaced also!

[wubsel]

Hey, Mario!
I have been told that if I go to a R-410 solution that I will have to change out the copper lines between the condenser and evaporator coil. Replacing these lines is a virtual impossibility the way this house is constructed. Is it possible to have these flushed out so they can be used with R-410 or am I stuck with having to stay with
R-22?

[wubsel]

Thanks, Mario! You guys are a big help!!!!!!

Wubsel

[beshvac]

Or just use Nitrogen on existing linesets. You can do a search on this site for the comments.