To Zone or Return? Plus which Carrier system?

16 years ago

Hello! We've just received a few quotes to replace our 1984 Lennox Pulse furnace and 2001 Goodman AC (the compressor went, and we're hot hot hot!)

The house:

L shaped ranch, 1278 sq ft, built 1958. The leg is bedrooms, R35, basement underground. The corner of the L is living room/kitchen with cathedral ceiling (maybe R10, poorly vented), one wall all glass, plus another large double window. Basement of this area is daylight, same wall of windows. Windows are East facing, we have lots of shade trees so only an hour or so of sun load in the summer. Dining room is off the kitchen in an addition (the little leg!), also cathedral ceiling, but over a crawlspace (floor insulated).

Quoted systems (from most responsive, thorough, and respected contractor in the area, and they had done the furnace in our previous home. Quotes include rewiring, new plenum, brackets for outdoor unit, etc. All 10 yr parts, 5 yr labor.

Carrier Infinity 3 stage, 58MVC 76,000 Btuh

Carrier Performance 2 ton, 2 stage 24APA724 18/24,000 Btuh 16.00 SEER Infinity control included.

$7333 (after cool cash rebate)

Carrier Performance 2 stage, 58UVB 76,000 Btuh

Carrier Performance 2 ton, 1 stage 24APA524 24,000 Btuh 15.50 SEER

$6203

Carrier Performance 2 stage, 58UVB 76,000 Btuh

Carrier Comfort 2 ton, 1 stage, 24ACC624 24,000 Btuh 16.00 SEER

$6206

So first question.....which system. Is the extra stage on the furnace and air worth the extra $1000, or is it extra stuff that is going to break and be costly to repair? We plan to be here probably 10-15 years.

The second question......

We have a temperature imbalance that we made worse by insulating the bedroom portion of the house. Not to mention that the thermostat is there. Oh, and the ONLY return is in this portion. It is central to the house and directly over the furnace. It draws great from the bedrooms, and a bit from the living room, but not at all from the dining room. We get about a 3-4 degree difference in the living room, and up to 10 degrees in the dining room.

The basement family room ceiling is tile, and we are fine with removing it and reconfiguring soffits and such.

Options:

We were quoted $1500 - $1800 for Carrier zoning, $1300 for Dura Zone. 2 zones, bedrooms vs cathedral areas.

Not quoted (because the ceiling is still up), to put returns in the living room and dining room areas.

From what I've read here, I'm not sure zoning is the way to go.....these are pretty old ducts and surely this will harm the system, or end up dumping so much as to not save any money or increase comfort.

But will the returns create enough draw to balance the system?

Should we do manual dampering instead? How about a booster fan for the dining room? (my FIL has 2 to give us).

We cannot afford both return ducting and zoning, and probably not the Infinity system and zoning, but perhaps the Infinity and ducting.

Any help or suggestions would be greatly appreciated. Thanks!!

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Comments (5)

dyeing2knit
Original Author
16 years ago
Gah! Location....we're in Iowa, right between zone 4-5.
tigerdunes
16 years ago
dyeing

what size furnace and AC are you replacing?

your ductwork system needs a thorough evaluation and inspection. returns are best centrally located in an interior hallway. you definitely need another return.

what mdl evap coil was quoted? this makes a difference.

your dealer has verified that these furnaces qualify for tax credit?

I see nothing wrong with the Performance 96 furnace. not as nice as the Infinity but you have to decide about the $1K difference. what mdl stat was quoted? it must have two stg capability.

what about air filter cabinet?

the Performance 15 AC is preferred over the Comfort 16.

IMO
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dyeing2knit
Original Author
16 years ago
Hi Tiger, thanks for chiming in!

The current Lennox G-14 is a 80,000 Btuh (I think...from reading the model numbers in the cabinet G1403-80-03. Plus another company quoted us an 80)

The current AC is Goodman CKT30-1, which a quick google tells me it is 2.5 ton.

We do plan to seal the duct leaks in the accessible areas of the basement, have installed interior storm windows on our huge windows, and with the addition of the R35 in the back of the house, I feel it is reasonable to go down in size. We do have considerable humidity, so for the unit to be running longer is a good thing.

Returns: The current return is in the most central part of the house. There are no other hallways, so those returns will need to go on room walls.

The main question is.....should we do the zoning? There isn't much room to work with in the furnace room, and they would need to do that during the install. I suppose it depends on the ducts. There's 3 main trunks, one to the bedroom portion, and two for the cathedral portion. One of those wraps around the fireplace & water heater chimneys, he did mention that that isn't ideal. We can have them come look at the ducting next week once we get the ceiling tiles down.

The tax credit is listed on all three options. That does help the cost....but of course not up front.

Hmmm.....not sure on the coil. It says: "Coil Type: Cased" for all three. Anything I should ask specifically about that, or which type (Looks like N or A) is better?

The middle thermo is just listed as Programmable Thermostat, and is included. (quoted as $65)
We could get the Thermidistat for $115....would it make much difference with the 1 stage AC? We are having the humidifier removed, we haven't needed it.

It does not specifically mention the air filter cabinet, but on the last install they did for us, it was the 5 inch pleated. He did mention it when taking measurements for the quote.

Again, thanks for your thoughts. Definitely helpful and giving me fodder for the next conversation with the contractor.
tigerdunes
16 years ago
the evap coil model is important. there are only a few choices that AHRI Directory lists as matches. not an issue to overlook.

as far as stat, I would go for the thermidistat that has two stg capability for the furnace. why spend thousands of dollars for a cheap thermostat that cripples and does not take advantage of a new system's capability.

and I do recommend a 4-5" pleated filter MERV 10 air filter cabinet.

IMO
dyeing2knit
Original Author
16 years ago
Thanks, I will look more into what the Thermidistat is compared to the regular and Infinity controls. I'll also ask for model #'s for the coils.

I tore down half the ceiling today, and....OH MY! It will be interesting to see the surprises under the other half, too!