RE: [GBlist] oversz air/heat unit?

[laura.aune@dfait-maeci.gc.ca]

Hello,

I spent some five years as the corporate controller for a large mechanical
contractor in the Dallas area and eventually became general manager when the
owner was out of town (or gone fishin'). We offered new and retrofit
installation and service of residential, commercial and industrial HVAC
systems among other things so I think I have a good handle on your question.

First, it goes without saying that you should take care that you are dealing
with a bona fide licensed contractor with a solid reputation and years of
experience and who stocks quality equipment such as Lennox, Trane, Ruud,
etc.    

Second, if you are having the full system installed, i.e. ductwork, etc. and
not just replacement equipment, the contractor should actually do a duct
lay-out (nothing highly elaborate like a blueprint, but at least a schematic
that shows some thought has been actually applied to your floorplan) that he
should be willing to show you. 

Third, if the contractor is truly a professional and deals in high quality
equipment such as Lennox, he should have ready access to at least one
computer program that models the structure, including r-values of the
windows and insulation (if known), window sizes and directional orientation,
average heating/cooling days for your local area, foundation and wall
structure types, roof type, etc. Lennox pioneered this approach in the 1980s
with its proprietary Lennox LOGIC system. Not only will the program select
the optimum unit size, it can analyze and compare estimated energy costs
(using the local average residential gas and electric prices per btu kw
hour) vs. installation costs for equipment with different SEER ratings
(measures of energy efficiency).

All that said, I wouldn't immediately dismiss the fellow out of hand for
simply giving you a ballpark size estimate. A seasoned, experienced
contractor can make a pretty good educated guess based upon his knowledge of
the local climate and square footage. In fact, his assessment that you might
need a 2 OR a 2.5 ton system shows that he is including some flexibility in
his thinking. 

One last thing on SEER ratings and equipment dealers - you may find that
your contractor/dealer offers manufacturer's financing such as Lennox at
competitive interest rates. Again, Lennox was a pioneer years ago in
developing computer programs that compare the monthly energy savings, both
in kw hours/BTUs and actual dollars, with the incremental monthly payment
for opting for higher SEER rating equipment (including interest costs).
Often the incremental energy savings exceed the incremental monthly payment,
so the payback was immediate. I have no doubt that these programs have been
even more improved and placed into much more widespread use, so I would ask
for such analysis from any prospective contractor.

I hope this is helpful and good luck!

Laura Aune
Business Development Officer
Canadian Consulate General - Dallas
750 N. St. Paul Street Suite 1700
Dallas, Texas USA 75201
voice: 214/922-9812 ext. 3357
fax: 214/922-9815
mailto:laura.aune@dfait-maeci.gc.ca
http://www.canada-dallas.org
  

-----Original Message-----
From: J Frost [mailto:jsf3018@neo.tamu.edu]
Sent: July 30, 2001 12:48 PM
To: greenbuilding@crest.org
Subject: [GBlist] oversz air/heat unit?


Just got off the phone with a  aircondition/heat contractor to set up
     an appt. for an estimate  to install  air/heat.
He said off the top of his head that  I would need a   2 or 2.5 ton 
unit.

Alarms went off in my head cause i know  you are suppose to put 
some effort into   " sizing" the unit correctly;  especially in my 	
	
humid climate.

 My question is,  how  can I make sure he is selling me the correct 
size unit?     any advice would be helpful.

Thanks in advance
jfrost

______________________________________________________________________
This greenbuilding dialogue is sponsored by REPP/CREST, creator of
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______________________________________________________________________

______________________________________________________________________
This greenbuilding dialogue is sponsored by REPP/CREST, creator of
Solstice http://www.crest.org, and BuildingGreen, Inc., publisher of
Environmental Building News and GreenSpec http://www.BuildingGreen.com
______________________________________________________________________