A/C sizing

[sd47]

From all I've been told, any house with less than 1600sq ft. would be unwise to use 2ton A/C as it will not properly remove humidity and result in a loss of the SEER value, due to constantly going on and off....any thoughts on this??

Also, rough rule of thumb is given as 1Ton per 1000sq ft??

[trane]

Somebody is telling you wrong.

[NormChris]

Guessing and/or using so called rules of thumb do not produce good results. Your need to read this.

http://www.hvac-talk.com/vbb/showthr...threadid=33866


A proper load calculation is the ONLY way to properly size a system!

[Mr Bill]

Originally posted by sd47
Also, rough rule of thumb is given as 1Ton per 1000sq ft??

I think that rule of thumb only applies in Alaska.

I would love to see you cool a 5000 sq.ft. home in Houston, Tx. with a 5-ton a/c.

[dan sw fl]

Originally posted by sd47
... any thoughts on this??

Also, rough rule of thumb is given as 1Ton per 1000sq ft??

This can almost be applied to homes With One 2' x 4' Window + maybe 1 Door__ Along with the ALASKA igloos.

[sd47]

Apparent I missed the obvious factors like direction of house facing, window area, shade factor, ceiling height, and a lot more, but what I was driving at was more todo with the SEER reduction than anything else??...or maybe I just answered myself...

[sd47]

I do appreciate the sarcasm however, although it wasn't particularly conducive to wanting to open my mouth again...lol

[dan sw fl]

Originally posted by sd47
Apparent I missed the obvious factors like direction of house facing, window area, shade factor, ceiling height, and a lot more, but what I was driving at was more todo with the SEER reduction than anything else??...or maybe I just answered myself...

...
1600 Sq. Ft may be well served by
a 2.5 or 3-ton, high SEER unit
with Variable Speed Air Handler.

[sd47]

I see you're in SWFlorida..so I guess I should have stated that I am in SW Ontario, Canada, where we get temps like 87 with humidex of 94 during our "heat waves"...and normal would be more like 82 with humidex of 88...much the same variance, but easier to live with the second set of numbers, if nothing else...

[dan sw fl]

Originally posted by sd47
I see you're in SWFlorida..so I guess I should have stated that I am in SW Ontario, Canada, where we get temps like 87 with humidex of 94 during our "heat waves

So perhaps, Igloos design rule may be Applied.

There might more than just a slight variation between the
Artic ( Ontario) and the Tropics (S. FL)

[sd47]

Assuming the Igloo rule is in effect,,what is the point behind using a 21/2Ton coil with a 2Ton unit??

[uktra]

Mrbillpro--If you look at some of the Building America homes by Pulte in Houston you will see about 1 ton per 1000 sq. ft. It's all in the way you build the home.

[faith]

sd47

"what is the point behind using a 21/2Ton coil with a 2Ton unit?"

The same physical coil element is rated at different capacities depending on the refrigerant control device supplying it. What this means is actual coil is a complex factor depending on more variables than mentioned thus far in this thread...

The only true authority on each unit is the vendor's rep that has to approve the replacement if there is a warranty claim (sad but true). Actually the engineers who design the Coils are totally aware of the performance curves from empirical testing data (which may differ from the original design data).

HVAC professionals have to go by the numbers and matching units provided be each vendor. There are times when "field modifications" are approved but they are the exception, not the rule.

What I’m attempting to say is do not focus on capacity numbers, but rather on compliance with the vendors specifications. Does this make sense?

[Panama]

Originally posted by uktra
Mrbillpro--If you look at some of the Building America homes by Pulte in Houston you will see about 1 ton per 1000 sq. ft. It's all in the way you build the home.

And design, install and commission the HVAC system.

[uktra]

Good job Panama--I should have included that!!

[sd47]

What I’m attempting to say is do not focus on capacity numbers, but rather on compliance with the vendors specifications. Does this make sense?

Absolutely, so the next question is where do you go to find the vendors specs without having to ask anyone...just trying to filter out diff opinions of diff HVAC contractors, so as not to confuse opinion with fact...thanks

[dan sw fl]

Originally posted by uktra
Mrbillpro--If you look at some of the

Building America homes by Pulte in Houston
you will see
about 1 ton per 1000 sq. ft.

It's all in the way you build the home.

UKTRA,

Please provide link to specifics like Floor Plan,
Window Area, S.H.G.C., U-value, Insulation values, ...

Now that's something WE Can ALL Learn from:
1,000 Sq. Ft./Ton

Does anyone else in Houston build to that level?

I'd like to know how to get just half way there...
800 S.F./Ton

[uktra]

Look up DOE's Building America site. Also [url]http://www.buildingscience .com

[dan sw fl]

I appreciate it