ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
Recent Posts
600 KW 120/208 3 Phase Y protection
by Yooperup. 07/24/17 12:20 PM
1913 American Electrician's Handbook
by gfretwell. 07/20/17 01:08 PM
Green House wiring
by ghost307. 07/20/17 09:10 AM
Permit Snafus...AHJs and Contractors Jump in
by HotLine1. 07/18/17 08:06 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
239,333 Are you busy
174,807 Re: Forum
167,184 Need opinion
Who's Online Now
0 registered members (), 55 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#19696 - 01/01/03 01:52 PM Rule of thumb for A/C  
wocolt  Offline
Joined: Dec 2002
Posts: 110
A family member is having there house sized for air-conditioning, and the HVAC guy is telling them they need a 7-ton unit.
the house is 2800 sq.ft.
This comes out to about 24500 VA just for the A/C.
Does this sound high to anyone else ???????


Work Gear for Electricians and the Trades

#19697 - 01/01/03 02:28 PM Re: Rule of thumb for A/C  
spyder  Offline
Joined: Oct 2002
Posts: 210
I am not an HVAC specialist, but 7 tons sounds like alot, but like anything else there are a lot of variables..such as high ceilings..etc...

#19698 - 01/01/03 02:44 PM Re: Rule of thumb for A/C  
Wirenuttt  Offline
Joined: Nov 2002
Posts: 267
Had an hvac specialist size up my home which was built in 95 for central AC. He said 3 tons would be plenty. It's a colonial with 1450 sq ft. this was not including the basement, stays cool enough down stairs. Duct work is insulated. We have 2 returns one on 1st and 2nd fl., which I understand is ok for heat, but a/c should really have a return in each room. There's thermal pane windows, an a high r value of insulation. They told me I can save $300 on installation if I do the wiring, the price was $2400., that's the condensor, A-coil and AC lines.
They told me a house like mine is basically 1 ton per 500 sq ft of floor space.

[This message has been edited by Wirenuttt (edited 01-01-2003).]

#19699 - 01/01/03 03:00 PM Re: Rule of thumb for A/C  
go-go  Offline
Joined: Aug 2002
Posts: 42

#19700 - 01/01/03 09:12 PM Re: Rule of thumb for A/C  
wolfdog  Offline
Joined: Oct 2001
Posts: 135
Rules of thumb are riddled with qualifiers.

Here in Dallas,Texas residential a/c is going to be 400- 500 ft² per ton.

How well insulated,how much glass, the exposures, the outside design temp. all figure in.

The link given above offers a heat/cool load calculation software package for homeowners at a very reasonable price and Don supports it well.

If in doubt, run the numbers and see what comes up. Too much a/c can be worse than too little.

[This message has been edited by wolfdog (edited 01-01-2003).]

#19701 - 01/02/03 10:47 AM Re: Rule of thumb for A/C  
wocolt  Offline
Joined: Dec 2002
Posts: 110
Thanks to everyone who replied. It is my sisters house and she and her husband are doing some remodelling, and the HVAC guys are installing the A/C 7 tons of it. and that comes out to 24500 VA or 102 amps of load since its A/C it has to be taken at 100 %, and the EC wants to put in a 300 amp service, and ironically enough they do live in Texas.
In light of that it looks correct. I understand that there are variables, and just wanted a ballpark to see if she was getting what she needed or getting ripped off.
So thanks again.

#19702 - 01/02/03 06:23 PM Re: Rule of thumb for A/C  
WARREN1  Offline
Joined: May 2001
Posts: 176
Greenville, SC, USA
I wonder if she considered other types of Heat/cooling? Such as geothermal? It has a lot of advantages and saves a lot of money in the long haul of things.

Member Spotlight
L.I. New York
Posts: 95
Joined: August 2003
Show All Member Profiles 

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.015s Queries: 14 (0.002s) Memory: 0.7839 MB (Peak: 0.9356 MB) Zlib enabled. Server Time: 2017-07-26 02:37:55 UTC