Alex wrote:

Hello, My wife and I are planning on enclosing our garage next summer, and
this will bring our 1600 sq house up to about 2100 sq. We planned on
upgrading the 23 year old central air/heat system in the house then,
but a couple of weeks ago the unit died and needs replacing now.

We currently have a 3 ton system but in anticipation of convering the
garage in we're upgrading to a 4 ton, 15 SEER system. I know if the
system is too large it won't remove enough humidity from the house and
mold can set in, plus shutting on and off alot is bad for the system,
however will us having the system in place for 6-8 months hurt it like
this? Winter is here, and I doubt we'll be using the air conditioner
much until next March or April, just the heat if that, but just curious
of what we need to look out for.

We live in Central Texas where the humidity generally stays around 50%
or lower, and only rarely jumps up to 65% or higher. I figure worst
case we can get a stand alone dehumidifier if humidity does become a
problem. Will this help? Alex


You should have posted here before making a decision, it's probably too
late now to use other options.

You are adding 500-sq. ft., if you know the materials that will be used
windows, insulation, etc., you should be able to do a heat-load calc.
How much airflow will your ductwork & airhandler produce, perhaps only
enough for the existing 3-ton condensing unit.
The 4-ton will only deliver what the airflow will permit! Read the
linked pages below. - udarrell

Perhaps you could have bought a small "mini ductless system"- Soleus-air
units have adequate airflow & eliminate adding ductwork.
Then you could have stayed with the 3-ton set-up.

--
PROPER A/C UNIT & DUCTWORK Sizing is over 70% of Operating Efficiency
http://www.udarrell.com/proper_cfm_b...syste ms.html
Solving - External Static Pressure (ESP)
http://www.udarrell.com/udarrell-air-conditioning.html