AC Sizing and compatability

[John]

My son and I bought a foreclosure for he and his wife to live in. We are having Gas heat and electric AC put in. My son is in construction and was given the name of an HVAC company who gave us a great price. They are recommending a carrier 120k BTU Gas furance and a 5 ton carrier AC (where the evaporator mounts on top of furnace). The house is about 1750 SF but we plan to expand ti to about 2300. Some folks are telling us these units are too big. and particularly with the AC too big is not good. (they say it will cool too quick and not remove the moisture)

By the way - the installer has already installed the 5 ton evaporator over the furnace. he claims he can still add a 4 ton compressor and "slow down the fan". Is this viable?

1) What would be the right size AC for this house? 2) can I have an evaporator and compressor taht are different sizes?

[Bubba]

Construction? What does he do? Hold a wooden handle and dig holes?

Good. A great price and a shitty install. What more could you ask for?

Sounds like you have the cart before the horse?

That would depend on what the load calculation says. What does it say?

You can have whatever you want. First I would look for a clue. Bubba

[Noon-Air]

Shopping for a comfort system by price only is about the most idiotic thing you can do.

Even at 2300 sqft, I can't feature that any home would need more than about

3 tons, unless it has 12ft high ceilings throughout the house and half the windows are busted out. Size the system for the *existing* structure. The only time to upsize the equipment is if the walls for the addition are already blacked in... otherwise its only a pipedream.

Listen to them, they are correct.

Make him take it all out, do Manual J, and Manual D calculations to correctly size the equipment and ductwork for the home.

Can't say without doing the calculations.

Do you want it to work as it was designed to??

Personally, it sounds like suspiciously like there is no licensed contractor and that you bought the equipment over the internet, now you have the wrong size, and don't have a clue how to install it, or what to do with it. Quit throwing good money after bad, and get it done right.

BTW... did anybody bother to tell you that equipment bought over the internet voids the warranty???

[Stormin Mormon]

So, where are you? Florida, or Dakotas, or what?

I have a hard time lining up 120K heat, and 5 tons of cooling. Something sounds a bit much.

So you got the furnace and the evaporator in. And now it occurs to you to ask if it's the right size? We are not encouraged.

[Bubba]

Where the hell is this "we" crap Mormon? You stand alone you idiot. You wouldnt konw if a 5 ton and 120K were a match if you had the load calcs on paper in front of you. Go get your pet bioulder and bash you head in with it, Stormy. Bubba

[John]

Thanks to all who tried to help me. And to those who felt they need to reap abuse on me - I have no idea what warranted it

To be clear - this is NOT an internet deal - I would never try to do something as complex as this a homeowner- I went out to 4 licensed contractors - all they were told is we want to convert to gas heat (it was oil hot air but unit was and ADD AC in a 1750 SF house we planned to grow to 2400 SF. All sizings and costs were left to them. The house is in Connecticut, was built in 1942 and in the woods - fair amount of shade. The selected contractor is licensed in the State of NY and has done many installations - his price was the best but there was no indication whatsoever there was any issue. Were it not for a person making a casual comment about the size of the units - I wouldn't even have been asking these questions. I made every effort to be legit and this is what I get - an oversized system and abuse from some of you? Thanks to those who tried to help. I will get with the contractor and try to get it downsized.

[Steve]

Thanks to all who tried to help me. And to those who felt they need to reap abuse on me - I have no idea what warranted it

To be clear - this is NOT an internet deal - I would never try to do something as complex as this a homeowner- I went out to 4 licensed contractors - all they were told is we want to convert to gas heat (it was oil hot air but unit was and ADD AC in a 1750 SF house we planned to grow to 2400 SF. All sizings and costs were left to them. The house is in Connecticut, was built in 1942 and in the woods - fair amount of shade. The selected contractor is licensed in the State of NY and has done many installations - his price was the best but there was no indication whatsoever there was any issue. Were it not for a person making a casual comment about the size of the units - I wouldn't even have been asking these questions. I made every effort to be legit and this is what I get - an oversized system and abuse from some of you? Thanks to those who tried to help. I will get with the contractor and try to get it downsized.

Demand a Manual J and Manual D calculation for your home....that will tell you *EXACTLY* what size of equipment you need. Unless you do the math, your only guessing. Our trade is based on math and science.... if the contractor doesn't understand this, and doesn't know what these calcs are, or how to do them, then find somebody else. Remember...You will have to live with the results for the next 15 - 20 years.

[Old and Grunpy]

John: I am not in HVAC business so I am not trying to sale anything If you need new furnace I would definitely replace old one with gas type burner it is chipper and far more cleaner. As to the size all it is need to know size of old one which it should be some place on name tag or label and get new one same size or little bigger because some time you are unable to get exact match. AC unit using thumb rule If you are living southern part of NY go with 5 ton up states use 4 ton should work however not to well Mix match is never good policy however you can use 4 ton on 5 ton Evaporator in northern parts of country but not in southern because of higher humidties it would not be taking it out as much as it should Tony

[warmairbob]

If you want the equipment and the duct sized correctly you have to do what is called a Manual J. In Michigan a 3 ton sounds right. In Florida or Arizona a 5 ton may be necessary. Downsizing equipment to evaporator coil is never the best option. A Thermostatic Expansion Valve (TXV) should be installed. Sounds like you have contractor will little experience, doesn't know how to size. A 90,000 BTU input furnace at 92% or higher would be OK.

[PaxPerPoten]

Did you look at the very old date on this posting from Noon-Aire?