New Furnace/AC System


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Old 04-06-09, 08:34 PM
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New Furnace/AC System

I am looking for a bit of guidance and recommendations for a new HVAC system. I have gotten several estimates from various companies and have narrowed down to the following:

Lennox: G71MPP + XC14 3 ton AC (15 SEER) + Healthy Climate HC10 Filter

Trane: XV95 + XL15i 3 ton AC (15 SEER) + Perfect Fit Media Filter

The estimates are very close and I expect both companies to do quality work. The Lennox dealer has been our service company for 12 yrs and the Trane dealer came highly recommended by several friends.

I have seen lot's of positive reviews of the XV95, but not so many on the G71 (probably cause it is new).

I would appreciate any comments regarding these systems to help in my decision.

Thanks!
 
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Old 04-06-09, 09:02 PM
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I can't find the manual on the Lennox.. I do recall that this furnace is not a true "variable stage" gas heat.

I recall something about after X amount of time, it will go into X-stage, and then locks into that stage. and so on.

The XV95 is a two stage furnace, and I'd suggest getting the Honeywell IAQ t-stat with this set up to get a full advantage of the system.

How big is your home and age?

How many BTU are they looking at for the furnace?
 
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Old 04-06-09, 09:14 PM
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Ok, I found it from one of my other post in the past.

"First stage calling, will run at 40%, and depends on t-stat cycle, it can fire from 40% to 90%.. If 2nd stage is called, then fires off 70% and do the % increeases untill stat is satisfied or reaches 100%. When demand is met at 2nd stage, and 1st stage is still called for, the furnace stays at it's fire rate till stat ends heat cycle.."
 
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Old 04-07-09, 06:01 AM
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Hi Jay,

The home is a split level built in the early 1960's with a new family room addition on the back. Total square footage is about 2000 sq. ft for this furnace/AC. The prior owners put an addition above the main living area about 17 yrs ago which is seviced by a separate furnace/AC. The only roof/attic area for the main part of the house that will be controlled by the new furnace/AC is above the bedrooms and the new family room.

While it likely isn't the most well insulated home, we did install new windows about 6 yrs ago (double pane w/ Kr gas) and this helped reduce the drafts significantly.

The Lennox furnace quoted was a 70,000 BTU, while the Trane was an 80,000 BTU.

BTW, we live in the suburbs of Chicago.

The Lennox G71 sounds interesting how it has different stages of burner operation, but since it is a new furnace I wonder about it's reliability. Don't believe that the Lennox dealer discussed the IAQ control...I will have to give him a call.

Thanks
 
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Old 04-07-09, 06:24 AM
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I don't advise putting a 90% furnace in the attic with our freezing winter weather. It just too risky for them to freeze up.

The new furnace is heating just the orginal part of the house, and that is 2,000 sq ft?
 
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Old 04-07-09, 07:23 AM
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Sorry...miscommunication.

I just pointed out the roof/attic to indicate potential heat loss (as I understand it).

The new furnace will be put in the basement utility/laundry room and will be responsible for heating/cooling approximately 2000 sq ft of living space.
 
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Old 04-07-09, 06:56 PM
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Has the dealer done a Manual-J (Load Calc) on your home?

With newer windows you may be able to use the 60K furnace from Trane.

Looked at Lennox, looks they don't go smaller than 70k.
 
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Old 04-10-09, 10:52 AM
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Smile

Jay,

Had 5 HVAC guys provide quotes (2 Lennox, Trane, Carrier and Bryant). Only the Carrier measured up the house, counted the windows and said he would do a heat load calc. I don't know what his numbers were and didn't expect him to provide them anyway. He didn't specify furnace size in his quote, only Carrier ICS furnace. Unfortunately, his quote was +25% higher than anyone elses. Not to mention he missed two appointments which were rescheduled after I called to find out where he was. Not a good first impression. Especially since I had taken off work one morning to meet with him! My wife said I should have kicked him immediately, but I like to give people second chances.

My current HVAC service provider (Lennox) and the Trane guy both measured up the house, calculated sq. footage, looked at existing ductwork, asked about the windows, discussed current heating issues (cold spots, temp swings, comfort, etc) and then estimated furnace size without looking at the existing furnace. However, no load calc was done. The other Lennox dealer and the Bryant dealer simply looked at existing furnace and based their estimates off of that...big turnoff!

I asked the Lennox dealer I liked about doing a Manual J and he told me that he doesn't do them. He did some several years ago and the outcome wasn't any different from his typical estimate. Therefore, he stopped doing them.

Incidently, the existing 25 yr old Carrier is 90,000 BTU and we added on about 450 sq feet to the home 2 yrs ago. So, I kind of feel that the 70K and 80K units are probably the right size. And as you pointed out, the 70K from Lennox is their smallest.

I am likely going to choose the Lennox system. I like the performance description of the G71MPP and he has been my HVAC service provider for 12+ yrs. He has always been responsive when my Carrier 58SSB was on the fritz...Beer 4U2
 
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Old 04-10-09, 02:26 PM
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Yeah, if you had good luck with the Lennox dealer over the years, then stick with him since you got a good relationship with them.

Did he say waht kind of t-stat they were plan on putting in?
 
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Old 04-10-09, 02:38 PM
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His first offer was a White Rogers 2-stage thermostat (Big Blue?), but after discussion agreed on Comfortsense 7000.
 
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Old 04-10-09, 07:47 PM
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From what I read, that t-stat is pretty close to the IAQ t-stat. (Not sure if I'd like how the screen is laid out on that)
 
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Old 04-10-09, 08:04 PM
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If your home is fairly typical of others in the general area that this guy services then his experience may indeed preclude the necessity of a heat loss calculation. I know that when I had my furnace replaced none of the five estimators wanted to do a heat loss calculation and when I asked the man that I was most impressed with he stated that was why he (and everyone else) asked about any new windows, weatherstripping, insulation and if I was comfortable with the existing furnace.

Furthermore, with the modulating function of the G71MPP you won't have a problem. The 70,000 BTU model will modulate down to about 28,000 BTUs per hour.
 
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Old 04-10-09, 09:26 PM
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Yep, that is what I figured as well.

The Lennox guy that I liked has been in the business for 31 yrs and he took over the company that his grandfather started 60 yrs ago. He has done quite a few furnace installs in those 31 yrs.

Although it would have been nice to have the heat loss calc, the variabilty of the G71 makes me feel pretty comfortable with the choice.
 
 

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