So our central air system died, home warranty replacing it, we’re paying extra for upgrade. Going from 4 ton system to 5 ton, replacing furnace, ducts, etc. Figure while they’re paying for part, we’ll pay for rest and get a badly needed upgraded system.
Trying to find reviews out there, so hard getting real info. Not sure I can get better here. =)
Consumer reports says all Carrier is pretty much in line with other systems, but some sites tear Carriers apart, say go with Lennox. Other sites say Lennox is junk, go with carrier. LOL. Are they basically the same? Carrier is what the guy we’re talking to is trying to get us to buy, I like him, like the install company, but want to check my info before I buy Carrier brand.
Also, what is best way to determine if I really need 4 ton or 5 ton sys? House is 1800 sq feet, very poorly insulated, lots of direct sunlight, so I think 5 is the way to go.
Any info at all would be useful for a total neophyte like myself. Thanks!
A heat load program should be run before installling a new system. You contractor should have access to a program.
For home units Carrier are fair units. I am not sure which is the best unit, it will be different with each teck.
If you live is a hot area over sizing a unit can cause some humity problems. But an over sized unit has other advantages. I have my stat turned up durring the day turning it down from 79 degrees to 74 30 minutes before I get home. When I get home the house is 74 and the unit is normally not running.
making a good heat load calculation is the important step. Any major manufacturer will be a good choice-a reputable installer is your best resource there. Just make it clear to him that cost isn’t the only factor, you want a unit that will be reliable and maintain it’s efficiency after years of use. Pay the extra $ for the unit he recommends. Of course the key is reputable installer.
The load calculation is the critical part. Since you are replacing a unit, that is you are already living there, you can help. You want a unit that maxes out (runs maybe 1/3 the time) on the hottest days, and runs frequently on a normal cooling/heating day. Remember, drying the air during the cooling season is very important to a successful A/C (this assumes you are in humid area. If you live in a place like Arizona then you have some natural advantages that can help). The only way it can do that is to run so bigger is definitely not better. If you can get by with a good 4 ton unit, it is a far better choice than 5 ton. What we did when we replaced our unit is remember what it was like in the kitchen on a July afternoon-and worked with the installer to size a unit to just barely handle that.
There is a $1500 federal tax credit for AC units. To get that you must have a unit that qualifies based on the SEER rating. Any good contractor can make sure the unit qualifies.
A heat load analysis is the way to go, but you also have experience with a 4 ton unit. DId the 4 ton keep the house cool? If it did, don’t go bigger.
If you live in a humid area, then as stated by others, this is important. You don’t want an oversized unit that is going to only run a short period of time (because it can cool the house so quickly), you want a unit that will run more often and for longer periods of time to dehumidify the air.
So have had lots of contractors give bids now. We had 3 1/2 ton, not 4, and house is so poorly insulated (built in the 50’s) that the 3 1/2 ton was awful. But I think I’ve got this covered, having had several a/c guys do a serious walkthrough.
Great. I hope it works out. Heres something to think about, however. Most homes will require **1 ton of cooling per 500-1000 per sf.
**
That’s a wide range because your cooling is a function of the quality of the envelope. A modern house with very high efficiency windows, door walls etc may get 1000 sf/ton, while an exceptionally poor envelope may only get 500 sf/ton.
You’re proposing a 5 ton unit for 1800 sf. That’s a ratio of 360 sf/ton. By way of comparison, we just did an 1800 sf house, built in 1915, wooden clapboard exterior with plaster/lathe interior, balloon frame with zero insulation in the walls, ceilings and roof. Zero insulation. The windows were the original single pane double hung windows that were so loose in the frame that the rattled against each other in the wind. We put in a 3.5 ton unit and they are thrilled with it’s performance.
My advice should be taken with a grain of salt, but my [20 year experience] hunch is that there is a different reason that the existing 3.5 ton didn’t work. It is logical and common for homeowners (and lazy contractors) to conclude that the problem is one of size, when often it is a maintenance issue.
Your unit may have a bad compressor, or expansion valve, or low on Freon or undersized duct work, or leaks in the duct work (particularly if it runs through an attic) or, or, or…
I haven’t seen your house, so maybe 5 tons is right. But I can’t think of any '50s era house we’ve done that had an envelope that required 1 ton/ 360sf.
If your [new] unit is oversized, it may have problems with humidity. An oversized unit will reduce sensible heat (temperature) so rapidly that it doesn’t run long enough to remove sufficient latent heat (humidity). So…you’re cool sure enough, but clammy.
Technically I think it’s a 30%-of-cost credit, maxing out at $1500 for any qualifying energy-enhancing improvements within the 2009-10 period. But good on you for pointing it out – the OP picked a good time to have the AC pack it in, if it had to at all.
Yeah the first contractor we spoke with was all about a 5 ton unit. Said we had a 4 in place. Never mentioned having to adjust duct work size, or redo electrical hookup, or seal existing ducts, etc. So he’s now out of the picture.
Have 2 other contractors giving real bids now. Both of them are saying they can install a 5 ton unit but that sealing the ducts and doing a 4 ton unit instead would be all we need, and they’d set it up so we could add zoning down the road if required.
We also have zero insulation in walls, and lots of large picture windows for a great view. All single pane, low efficiency windows. No attic. Roof is dark and flat, with about 1/2" insulation in roof. I’m tempted to buy white reflective paint and cover roof with it. =)
