Installing central ac unit with current heating furnance

11 years ago

Hey all,

I am looking to install a central ac unit, I already have forced air heat in the house with duck work already in place. I have a furnace in the basement.

I have been hearing different things for installation of ac.
Home depot tell me i need a unit in the attic and new duck work because the old ductwork might night be big enough.
Sears tells me they can put the unit on top of my existing furnace and it will be able to push the air up.
a private contract guys tells me what home depot told me

What do you guys think what should I go with, sears gave me the best possible price because there is no new duct work. They give me a price for 5K and home depot for 11k private guy for 10k.

Thank you for your help.

Featured Answer

snoopdoggydoug43

11 years ago

Your situation was the same as mine when we had our home built in 1977, heat but no AC. Had a unit installed the following summer, (we moved in Oct, and house is 1800 sq ft). We had a 3 1/2 ton put in, which lasted until 2010, when we had a new furnace and AC system installed. Our furnace is also in the basement, and there is NO, problem moving the air, although we do change vent position for summer and winter, as cold air drops, and heat rises. At 1500 sq ft, you would most likely need a 3 ton unit, a 13, 14 seer would probably work, BUT, if the humidity is high, I would check a higher seer, 2 stage unit, as the first stage runs on low, keeping humidity down, and when cooling is called for, the second stage takes over, this is probably the only mistake I made living in Chicago, when it is humid in the summer. If you subscribe to something like Angie's list, they can direct you to a good installer, friends of mine got a great installer from Costco, and it did not cost $5000, more like half that amount.

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Comments (12)

tigerdunes
11 years ago
All I can say is never ever purchase HVAC from a big box store like HD or Sears.

Look for a reputable dealer in your area.

What is location?

What is size of your home?

You will need outside condenser, matching inside evap coil, and new and correctly sized refrigerant lineset.

Ductwork should be inspected possibly with some modifications but I see no reason to replace it.

I would add a media filter cabinet at return end of furnace if you don't already have one in place.

IMO
nycnhp
Original Author
11 years ago
Thanks tigerdunes,

I am located in new hyde park, ny. The house is about 1500 SQ foot.
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mike_home
11 years ago
Do you know the size of your current furnace? The brand and model number would be helpful.

Do you get good air flow to all the air registers? Is the duct work accessible in the basement? What type of house do you have? Do any of your neighbors have a similar model house with the AC integrated with their furnace?

Get more quotes from HVAC contractors. This is the best time of the year to get their attention. You should be able to add a coil onto your furnace. I would avoid installing an air handler in the attic.
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handy-man
11 years ago
nychnp,

If your house has heat only, then 98% that your ducts are for heat only and not A/C. You might want to replace/enlarge the ducts for more efficiency. You can add in A/C without replacing the ducts, but be prepare to have problems later. As for furnace, depending on what type of furnace. Older furnace don't have the capable to deliver the right CFM. What is the age of your furnace? Just a gut feeling, I think that home depot and the private contractor are right.
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mike_home
11 years ago
The duct work has to be sized properly for the required air flow. In the New York area the air flow requirements for heating and cooling are about the same for a typical house. Just because a furnace is older does not mean it can't deliver the required air flow for AC. Older furnaces tend to be over sized so it is likely the blower is large enough. Some furnaces will have heating and cooling settings for air flow.

Is this a one story or two story house? Are you including the basement area in the 1500 sq. ft? If yes, what is the area of the first and second floors?

My recommendation is to find a good HVAC contractor who will spend the time to review you duct work and furnace, and sit down with you to review the options. I have to think there are some good companies in Nassau County. Please stay away from Sears, Home Depot, and Lowes.
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southerncanuck
11 years ago
DISREGARD POST

This post was edited by SouthernCanuck on Wed, Apr 3, 13 at 11:12
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stoveguyy
11 years ago
I like the last post. Might cost 5k but should only cost 2500! Sure the parts are 2500 and install is free. U price out a new furnace and ac and it's always around 7500. Or closer to 10k for really good stuff.
snoopdoggydoug43
11 years ago
I agree with you cavell, replacing an entire system, furnace and AC, will cost anywhere from $6, to 8000, as it cost me that much to do. But I do not recall, the poster, saying he was replacing the entire system, only adding AC, to his exsisting furnace system. So, is he replacing the entire system ????, or just the AC, and if it is JUST, the AC, it should not cost 7 to 10K. A 13/14 seer, 3 ton unit should be somewhere in the area of 1300, to 1500, with install around 1000, as long as it is a std install, without a ton of extra sheet metal work.
tigerdunes
11 years ago
For OP's location and decent home insulation properties, I would think a 2 1/2 ton size, 13 SEER with matching coil.

IMO
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mike_home
11 years ago
" A 13/14 seer, 3 ton unit should be somewhere in the area of 1300, to 1500, with install around 1000, as long as it is a std install, without a ton of extra sheet metal work."

I would think it would take two people most of a day to install an AC condenser, coil, line set, and modify the duct work to accommodate the new coil. A $1000 in labor and materials in not going to cover the costs and profits in most parts of the country.

You may be able to find a builder's grade 3 ton AC condenser for $1300 - $1500, but your are over looking the cost of the coil, line set, sheet metal, wiring, switches, and all the other parts needed to complete in installation.

I would be curious to know what AC condenser and installation your friends got from Costco for $2500.
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Isabel Stone
6 years ago
Oooo these are all great tips! Thank you this is actually incredibly useful! The thing is I’m looking for an A/C unit for the office I run (basically the temperature is so up and down that we basically NEED one to just keep things acclimatised). It’s not a huge office perse but it’s also not huge. I also really don’t want to get a measly little thing that doesn't make any difference, I’d rather just invest in a solid product. So I was wondering really what people’s preferred A/C unit is? Or if not that, which one their office uses and if it’s good or bad or not? Also where is the best place to buy A/C units? (I literally have no clue), I came across this retailer which is near to the office, has anyone used them or heard of them before? (this is them: http://www.easyairconditioning.com/). I am surprisingly (or not) not exactly an air conditioning expert so any advice or recommendations would be much appreciated!
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Installing central ac unit with current heating furnance

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Installing central ac unit with current heating furnance

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