udarrell wrote:
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

Hi...

Yup, too late as the new unit is almost installed. Thanks for the
links, but they are quite over my head I guess. Everything I've read
or seen says 1 ton per 500sq is generally excepted. My house is
exactly 1660 square feet, and we will be adding roughly another 500sq
to this in 6-8 months. It made sence to upgrade from a 3 ton to 4 ton
unit if this is all true. I can see how there are other options, but
is the option I went with bad?

The garage room will be standard room, drywall, insulation, windows and
doors I guess as efficient as I can afford once we get to that point
(in the garage conversion). As for the rest of the house, it's a 23
year old house, and though probably not the most energy efficient house
out there, I think it holds its own.

My question though was more along the lines of the larger AC unit for
less square footage until we can convert the garage in, and how this
will effect humidity in the house or effect the AC unit itself.

Thanks for the info though... and I do want to read through it further.
If I didn't make the best choice then I'm probably not the only one
out there who's done the same thing. As with any market where I'm no
expert I can only go by the guidance of others in the field, and the
route I took was suggested by many, including those not involved with
the company I bought the AC from.

Take care --

Alex