Upgrading AC/furnace system


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Old 10-13-21, 06:45 AM
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Upgrading AC/furnace system

Looking at installing 2 new AC/furnaces. Looking at 16 SEER with 2 stages. Current systems are 10SEER installed in 2002. Installer indicated that I might need new thermostat wiring to and from thermostat, condenser and furnace/air handler. That could be a little challenging since my home is finished on all three floors. Do I need anything more than 5 wire thermostat wiring? Perhaps he is referring to something different.
Ian
 
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Old 10-13-21, 08:51 AM
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Yes, some two stage systems require six conductors but I think some furnaces can use a two wire digital system or even wirelessly communicate between the thermostat and furnace. Of course the non-standard systems have an extra cost.
 
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Old 10-13-21, 09:27 AM
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Is it ok to ask equipment/brand specific questions wrt to requirements? Installer doesn't want to quote a 2 stage AC since he doesn't want to have to run new wiring. What I proposed was that I would handle making sure the wiring was where it needed to be. I will check the wiring when I get home. I think I already have 5 or 6 wire conductor thermostat wiring going everywhere but would like to confirm what is going to be needed for these AC/furnace/air hander systems.
Ian
 
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Old 10-13-21, 10:44 AM
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Gas furnace with split A/C ?
5 - 6 wires needed.

R - 24v
G - blower
W - heat
Y - cool
Y2 - second stage cooling

If you go wifi stats....
C - common
 
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Old 10-14-21, 05:43 AM
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Turns out I had 6 wires. so not a problem. Installer I am hoping to use doesn't want to install split AC system. He claims the effort and cost are not worth it. Does that opinion make sense.
 
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Old 10-14-21, 07:11 AM
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Previously you said the contractor didn't want to install a two stage system. Now you say he doesn't want to install a split system. Aside from the HVAC person not wanting to do several things, what are YOU calling a "split system"? Are you referring to mini-split or an exterior condenser with an interior coil & furnace?
 
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Old 10-14-21, 09:09 AM
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That is my fault using the wrong terms. I was thinking I wanted a 2-stage AC for both systems I am replacing. I was surprised when he indicated that it was more work and cost and didn't want to do it. I did understand that the system would be more expensive but I didn't expect the installation to be more complicated.

I have a meeting on Friday afternoon to finalize scope on the 2 system replacements so we are both talking apples and apples. Based on his comments, I am now looking at a 2Ton 16SEER and and 2.5Ton 16SEER with new furnaces.
As always I appreciate everyone's comments.
 
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Old 10-14-21, 09:43 AM
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What reasons is the installer giving for not doing a two stage? Just saying "it's more work" would not satisfy me. Are their reasons reasonable to you and do you want to stick with this installer? If you are doubtful about anything I would talk with some other HVAC contractors.

I have rental property and buy several+ systems a year and my installer is up front when I ask about different levels available, their cost and pro's and con's. These days you also need to ask about what is available in a reasonable timeframe.
 
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Old 10-14-21, 10:17 AM
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I will find out more on Friday when we meet in person to go over scope. I guess a question is "Is 2 stage worth the extra cost?" It gets you to 17SEER but would I actually notice that? I am guessing that 2-stage would last longer? Less noisy?
I am in Atlanta to summer heat/humidity is pretty bad
 
 

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