Urgent A/C and furnace replacement questions

10 years ago

Hi, IÃ¢ÂÂm going to replace the original builder A/C and the furnace that are over 20 years old because of refrigerant leakage. My situation is as follows:
Ã¢ÂÂ¢ Baltimore area
Ã¢ÂÂ¢ Built in 1992
Ã¢ÂÂ¢ 2-story, 2,600 sq ft, plus 800-1000 sqft finished basement
Ã¢ÂÂ¢ Summer thermo set at 77 degrees, winter thermo set at 67 degrees
Ã¢ÂÂ¢ Natural gas furnace and indoor coil installed in basement
Ã¢ÂÂ¢ Current (builder) system: outside unit HEIL CA5042VKA1 (3.5 ton?), inside unit NUGE100BG01 by Inter-City Products.

IÃ¢ÂÂm quoted a few Trane systems (mostly 4-ton). The one IÃ¢ÂÂm leaning towards is:
TRANE 4TTR6042B XR16, 3.5 Ton; XV80 TUD2C080B9V4, 80%, Two stage, Variable speed. Matching coil to achieve SEER 16.0, EER 13.0. Honeywell 8000 series thermostat. Price installed is in the ballpark of $6K.

Is this a reasonable system? And specifically:

1. The contractor had not done a Manual J calculation when I asked him. He said the ductwork is good to handle even a 4-ton system. I asked him whether 4-ton would be too big, and he answered 3.5 ton would be okay but too few models to choose from in the 3.5 ton category.

2. In terms of extracting moisture for better comfort, is the single-stage XR-16 good when pairing up with the variable-speed blower? Or should I pay $1.5K more for a 2-stage XR17?

3. Is it okay to replace the current 100K input BTUH furnace with the 80K BTUH XV80? With the 2-stage, variable-speed, will the house get enough heat in winter?

4. Is the Honeywell 8000 series thermostat good enough? IÃ¢ÂÂve seen a lot of posts advocating for Ã¢ÂÂVisionPro IAQÃ¢ÂÂ; should I upgrade?

As the temperature is rising in the next couple days, I really need to make a decision as soon as possible. Greatly appreciate any feedback from the pros here!

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Comments (6)

mike_home
10 years ago
Just because your duct work can handle a bigger condenser is not a good reason to increase the size. Your contractor should spend the time doing a load calculation. If the 3.5 ton condenser cool the house well in the past then there is no reason to increase the size. Single stage condensers are available in half ton sizes, while 2-stage condensers are only available in whole ton sizes.

I recommend you get a quote on a 95%+ efficiency furnace. You will save money on fuel and you may qualify for local rebates and tax credits. An 95% 80K BTU would be adequate, I am not sure about an 80% model.

A 2-stage AC should do a better job of humidity control. How as the humidity control with your old AC?

The Honeywell 8000 is fine. I would get the version which has the cool to dehumdify function.
tigerdunes
10 years ago
An 80% eff furnace for Baltimore is a dinosaur.

Go with 80 K XV95 and HW VP IAQ thermostat.

I would want a system that qualified for Fed Tax Credit.

IMO
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seansean
Original Author
10 years ago
Thank you both for the replies!

@mike_home: Perhaps because I usually set the AC temperature to be 77-78F, at times I do feel a bit uncomfortable on the 2nd floor when the outside is only moderately hot. The 2nd floor doesn't go below 80F. Therefore I can't be sure whether humidity contributes to the stickiness on the 2nd floor. Maybe a little bit.
But I'm hoping the variable-speed blower can help and I don't have to pay more for the 2-stage AC.

@tigerdunes: The contractor's proposal says the systems qualify for federal tax rebate of 10% of the total cost up to $500.

I'll be sure to get a thermostat with the cool to dehumdify function.

The contractor said 95% furnace would need PVC flue piping. I'm not sure what that meant, but I guess I should just get a quote for XV95 with the PVC flue piping done.
mike_home
10 years ago
A variable speed furnace may help the second floor cooling issues. More than likely you may need to increase the duct work to the second floor. It may also be possible to add manual dampers in the duct work to help balance the first and second floors.

A high efficiency furnace needs to vent through PVC piping out the side of the house. This adds to the cost of the installation.

I don't understand how you can get a tax credit with an 80% AFUE furnace. The credit is $150 for a 95%+ furnace, and $300 for a 16 SEER and 13 EER AC.
seansean
Original Author
10 years ago
Hmm...I'll ask the contractor about the tax credit qualification!

I'll check with the treasurer on the additional 2nd floor ductwork. :) We'll see.
weedmeister
10 years ago
A variable speed blower will do a good job removing humidity. though a 2-stage condenser will do better. $1500 better? I can't say.