Return to the Heating & Air Conditioning Forum | Post a Follow-Up

 o
Central A/C Proposal - Seem undersized?

Posted by stuntmanmike (My Page) on
Sun, Jan 29, 12 at 23:06

Hi HVAC experts.
I recently got a quote for a new a/c install, 1750 sq ft house with radiators, so would involve running new ducts and such. A 2 Ton Airease 13 SEER system was quoted. Think that's enough horsepower? House is circa 1840 and has relatively low ceilings, but single pane glass with some insulation.

Please let me know if this seems woefully underpowered or if you think it could work. It was also suggested that we only put in one zone, with the thermostat on the 2nd floor.


Follow-Up Postings:

 o
RE: Central A/C Proposal - Seem undersized?

Mike

What is your location?

What is your fuel for the radiators-nat gas, oil, propane?

What eff is your boiler?

Yes, I would say a two ton is probably undersized by up to one ton? You will only know for certain by getting a man J load calc for correct sizing. Keep in mind ductwork has to be sized correctly as well including adequate return for best airflow and overall comfort.

New ductwork should be insulated min R8.

I might even consider a HP depending on your location to handle heating needs for above freezing temps. Of course, I would want to know your electric rate and the cost of fuel for your boiler and its efficiency.

IMO


 o
RE: Central A/C Proposal - Seem undersized?

Can you provide some more details? Are you keeping the existing heating system and adding central AC only? How and where are the new ducts and returns being installed? Why only one zone if the house has two floors? Where will the air handler be installed?

It is difficult the tell if the size is too small. It would seem it would be undersized based on the house probably does not have much insulation. You need to have the contractor explain the reasoning behind his recommendations.


 o
RE: Central A/C Proposal - Seem undersized?

Hey guys, the house is in the hudson valley, ny. Keeping the hot water system but good call on adding heat pump for above freezing days.
Installer came back and recalculated, suggesting a 2.5 ton system (3 ton air handler.).
Airease equipment ok? Seems like a builders grade lennox and that it may share coil and internals with other premium brands?

Thanks


 o
RE: Central A/C Proposal - Seem undersized?

Airease is mediocre HVAC.

I would want to see the load calculation in writing. Not convinced that 2 1/2 ton might also be undersized for an old home with questionable insulation and building envelope properties.

Where will ductwork be placed? Crawlspace or attic? Ductwork insulation should be minimum R8 if not higher.

What is your fuel for the boiler and it's cost? What is boiler efficiency?

IMO


 o
RE: Central A/C Proposal - Seem undersized?

Hi guys, oil fired boiler is circa 2007, not sure of it's exact efficiency.
Ductwork to be run from air handler in attic and will be insulated.


 o
RE: Central A/C Proposal - Seem undersized?

stuntmanmike

Since your fuel is oil, your boiler is probably around 80-85% efficient.

What is your electric rate?

I would look into installing a good quality HP instead of straight AC. HP should have electronic demand defrost. I would not have an Airease.

IMO


 o
RE: Central A/C Proposal - Seem undersized?

I agree with Tiger completely, if your heating with oil, and planning on getting central a/c, spend a little more and updagrade to a heatpump. I'm assuming you don't have crazy expensive electric ofcourse.

I would probably go with 3 tons. That might be sized better since that house is so old and the sq. footage. Where are the vents being retro-fitted into? Basement or attic?


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Heating & Air Conditioning Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here