Replace/upgrade my system now or later?

[kropotkin]

I've the following system in a dormitory building in Austin Texas - the system runs a lot!

2x 5 Ton Bryant compressors no heat pump 10 SEER feeding into 1 Carrier 10 ton air blower/coil. (I think this has TXV valve(s).)

This complete system was installed in 2000.

In 2002, 2003 the original Millenium scrolls blew and were replaced by Copelands. The system has run fine since.

I've three thoughts I'd appreciate feedback on:

Replace the compressors with R-22 13 SEER units before January 2010 and keep the existing blower/coil. Reasoning: compressors are likely to die in the next 1-3 years anyway and I cannot buy new R-22 units after 1/2010. Energy savings from the 13 SEER would be nice.

Do I need to be concerned about a mismatch between 13 SEER units and the air handler/coil? In 2000, I believe I had the option of 13-14 SEER units so the system may be adequate in that regard (?)

If I want to install R-410A units would just the condenser coil need to be changed / re-designed? Or would the whole blower device (squirrel cage, motor, etc) need to go as well? If I were to go for R-410A, I would probably wait another couple of years to do so.


If there are any points you could suggest given my circumstance and that I'm over-looking, it'd help me.

[hvac Denny]

First of all I would call an HVAC company out, to better understand and serve what you're trying to accomplish.

But from a tech point of view, you've got to match the BTU Tonnage (5 with a 5, 6 with a 6, whatever the original one is.)

The SEER Rating is a good way to save money, and get the 1500$ tax credit. It won't play much of a role in the mechanics of fitting different parts of the system together. Again, it's all about matching the Tonnage!

And third, compressors shouldn't die in 3 years, that means your system definitely has some issues relating to liquid entering them, or improper ventilation of some sort. That NEEDS to be solved if they're dying that quickly.

Last, Refrigerant-22 equipment is about to become illegal to manufacture very soon. I recommend that you get a R-410a system or a R-407C system(407c being the close to drop in replacement for current R-22 systems).

hope this helps

[kropotkin]

My biggest concern I suppose is putting 13 SEER units on a coil designed for 10 SEER. These are 5 ton units and there are indeed TXVs on them.