Help! I have no idea how to choose

[mwvt9]

I am moving into a 44 year old 2,200 sq foot place in SW PA. It is two story. It currently has only radiant baseboard heat. I am looking to put in AC with a heat pump (redundent?). It will be an attic install.

Contractor 1:
One (1) Trane XL15i, 15 SEER, 3.5 ton heat pump (410A Refrigerant)
One (1) Trane, 5 ton, Variable speed, Air Handler (410A Refrigerant)
One (1) Trane Digital Programmable Thermostat
Attic Fan
Duct to be sized, fabricated and installed per SHEET METAL & AIR CONDITIONING CONTRACTORS OF NORTH AMERICA (SMACNA) standards for our industry using 26 gauge sheet metal.

Contractor 2 (has won numerous local awards):
Carrier Perfermance 3 ton heat pump
Carrier 3 ton variable speed air handler
Programmable thermostat
Attic Fan
Ducts will be insulated heavy gauge flex duct

Contractor 2 says the tonage mismatch in contractor 1's quote could cause humidity problems and that the system as a whole is overkill. He was the only one (out of 6 quotes to go with a 3 ton system). After voiceing this concern he called back with a 3.5 ton system at the 3 ton price or a discount on the 3 tons.

Flex duct and smaller tonage has me worried about number 2, but they appear more knowledgable overall.

Any suggestions? Thanks!

[gary_g]

You need a Manual J heat gain/loss calc on the house to determine proper sizing.

Get the exact model numbers of the condenser (outdoor unit) and air handler (indoor unit).

Are you keeping the current baseboard heat?

The air handler will need electric resistance strips to temper the cold air during a heat pump defrost cycle. Are you getting these strips?

FYI: A heat pump is a central a/c condenser that reverses refrigerant flow to provide heat in the winter.

Good luck.

[BaldLoonie]

Trane calls for the 065 air handler for getting the tax credit. On high end Carrier, they've removed the size from the model number and Trane will be doing the same. If that's an approved match, no problem with it. Humidity removal capacity would be the same as the smaller air handler but the overall capacity is slightly higher.

Metal is a nicer duct system but pretty rare to have it in an attic. If sized, designed & installed right, flex will work fine. Trouble is it is usually undersized and usually poorly installed.

How did these guys arrive at sizing? Look through some of the threads, especially those complaining about short cycling, higher bills, higher humidity. All have an oversized unit in common. If 3 tons is what the house needs, that's what it should have. Obviously the Carrier guy thinks so. Most dealers would rather oversize than undersized. Rarely get a complaint that way but if the unit doesn't keep up on a super hot day, you never hear the end of it. Usually those quoting smaller have done the calcs to support their sizing.

[mwvt9]

Trane calls for the 065 air handler for getting the tax credit. On high end Carrier, they've removed the size from the model number and Trane will be doing the same. If that's an approved match, no problem with it. Humidity removal capacity would be the same as the smaller air handler but the overall capacity is slightly higher.

Metal is a nicer duct system but pretty rare to have it in an attic. If sized, designed & installed right, flex will work fine. Trouble is it is usually undersized and usually poorly installed.

How did these guys arrive at sizing? Look through some of the threads, especially those complaining about short cycling, higher bills, higher humidity. All have an oversized unit in common. If 3 tons is what the house needs, that's what it should have. Obviously the Carrier guy thinks so. Most dealers would rather oversize than undersized. Rarely get a complaint that way but if the unit doesn't keep up on a super hot day, you never hear the end of it. Usually those quoting smaller have done the calcs to support their sizing.

Both will qualify for the federal tax credit. Until a few days ago I would have also got a $500 credit from the state of PA, but the program was abubtly ended.

For sizing, both guys used blueprints for the house and a walkthough the carrier guy used standard form while the trane guy seems to be doing a more one off design.

[mwvt9]

You need a Manual J heat gain/loss calc on the house to determine proper sizing.

Get the exact model numbers of the condenser (outdoor unit) and air handler (indoor unit).

Are you keeping the current baseboard heat?

The air handler will need electric resistance strips to temper the cold air during a heat pump defrost cycle. Are you getting these strips?

FYI: A heat pump is a central a/c condenser that reverses refrigerant flow to provide heat in the winter.

Good luck.

I will keep the baseboard heat, but only run it when it gets pretty cold and the heat pump becomes less effective. I am also using the heat pump as insurance against people not liking the baseboard heat (the looks of it) in the event of resale.

[davefr]

Flex duct and smaller tonage has me worried about number 2, but they appear more knowledgable overall.



Go with tin. I hate saran wrap ducts:mad:

[man from trane]

2200 Sq. Ft. above ground? I can't see 3 tons working unless your house is a cave or has no windows. If it did it would amaze me. Manual J or not, there are just certain laws of physics that cannot be broken. In a 44 year old house, if I were the installing contractor I think I would lie awake most nights until the first week of 95 degree temps passed with no call backs. :( If it did work, heaven forbid you have friends over for dinner on a 95 degree day.

Many times I've seen homes with equipment that was literally double the size it required and the homeowner had no complaints at all. Half a ton over, or even a ton over on that house is not going to be noticed by even the most obsessive-compulsive person.

But I'm not there and did not do the calcs so don't pay much attention. :)

[mwvt9]

2200 Sq. Ft. above ground? I can't see 3 tons working unless your house is a cave or has no windows. If it did it would amaze me. Manual J or not, there are just certain laws of physics that cannot be broken. In a 44 year old house, if I were the installing contractor I think I would lie awake most nights until the first week of 95 degree temps passed with no call backs. :( If it did work, heaven forbid you have friends over for dinner on a 95 degree day.

Many times I've seen homes with equipment that was literally double the size it required and the homeowner had no complaints at all. Half a ton over, or even a ton over on that house is not going to be noticed by even the most obsessive-compulsive person.

But I'm not there and did not do the calcs so don't pay much attention. :)


I think the basement is in the 2200 square feet and it is below ground. I think I am going to go with the bigger system anyway.

Around here a 90 degree days is VERY rare.

[BaldLoonie]

Around here, 2200 sq ft would be sometimes 2.5 ton, usually 3 ton. Rare to be bigger. We get into the 90s each summer with some healthy humidity. Maybe we build our houses better here.

We have a customer with 3500+ house and 5 ton, they can keep it in the mid 60s!!! We had to put a freeze stat on it so it didn't freeze at night :eek:

[dash]

As mentioned,no one wants to undersize a system,so usually the one quoting the lower tonnage is correctly sizing it,and the others are guessing, that's been our experience here.

If you go with the 3 ton,I'd mention that everyone else was 5 tons,and ask if they are sure.

[heatpumpguru]

PA dropped $500 rebate because the state budget has not passed and the funding has been pulled as of 4 August

[mwvt9]

As mentioned,no one wants to undersize a system,so usually the one quoting the lower tonnage is correctly sizing it,and the others are guessing, that's been our experience here.

If you go with the 3 ton,I'd mention that everyone else was 5 tons,and ask if they are sure.

I asked the guy with the 3.5 ton (with 5 ton air handler) to recheck the manual J calculation. He said that with a certain insulation in the walls it was cominup up around 3.4, but if the insulation was better it was around 2.9. To this point nobody has been in the walls to take a look.