New AC Furnace

CopFiveOApril 15, 2014

I have a question concerning thermostat selection. Installers are here installing a new
Trane XL18i AC unit 4TTX8036 A1000A
Trane coil 4NXCB032 AC3HCA
Trane XV95 furnace TUH2B080A9V3VB
Trane Humidifier THUMD200
TRANE TCONT602AF22MAA THERMOSTAT

CAan someone explain why they are installing the 602 and not the 803 thermostat??

What are the differences and pros vs cons. Not understanding the dealers explanation.

I read that the 602 controls stages off the furnace board and the 803 controls off the thermostat?

Help...

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CopFiveO

1532 square feet 2 story with unfinished basement built in 1996

    Bookmark   April 15, 2014 at 10:12AM
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tigerdunes

What is your location?

Single family home?

Crawl space?

Where is existing furnace located?

Looks to me that you are being oversized.

If you are going with 2 stage furnace, you want a true two stage thermostat that controls the staging, not the timer on control board that will always put you in high stage whether needed or not.

What size furnace and condenser are you replacing?

Post back.

IMO

    Bookmark   April 15, 2014 at 10:23AM
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CopFiveO

Columbus Ohio
Unfinished basement
Furnace is in basement
Ac outside
Replacing
Trane XB80 furnace TUD060C936H1 60,000 BTU
Trane XB1000 TTB024C100A0 not sure how many tons

Can you help me explain to installer why I don't want a 602 thermostat. I'm a cop not an HVAC guy and I'm at a loss on how to explain it.

I am also installing a whole home humidifier if that helps or matters. I don't need internet connectivity and dealer is trying to upscale home automation.

    Bookmark   April 15, 2014 at 11:02AM
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CopFiveO

Just remembered old Ac was 2.5 ton new Ac is 3 ton

    Bookmark   April 15, 2014 at 11:17AM
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tigerdunes

You are being oversized.

I did explain about the thermostat. Quite direct and simple.

If you are going with 2 stage furnace, you want a true two stage thermostat that controls the staging based on demand, not the timer on control board at furnace that will always put you in high stage whether needed or not.

IMO

This post was edited by tigerdunes on Tue, Apr 15, 14 at 11:56

    Bookmark   April 15, 2014 at 11:22AM
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CopFiveO

Thank you for your help. Should there be any testing of flow rates thru the system after the install? It's frustrating to pay thousands of dollars and having zero knowledge on the subject at hand. Let alone how the install should be done correctly. Again, thank you so much for the info.

    Bookmark   April 15, 2014 at 11:26AM
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mike_home

I am going to speculate the reason you are getting the 602 vs. the 803 is that you don't have enough wires to control the 2-stage AC and 2-stage furnace. The 802 will need two wires each to control the two stage. The installer may not want to pull the additional wires. If there are extra wires, then there he is just being lazy and not wanting to bother to connect the two extra wires at each end.

Your old AC is 2 tons. The "24" in the model number means 24,000 BTUs which equals 2 tons. Your old furnace was 60K BTU at 80% efficiency. This means the output was about 48,000 BTU. Your new furnace is 80K BTU at 95% efficiency for an output of about 76,000 BTU.

Low humidity in the house usually means the house has air leakage problems. I would try to tighten up the house before installing a humidifier.

You are being over sized on both furnace and AC. You are paying more money of a system that will not work as well as your old system. Right now the thermostat is the least of your problems.

    Bookmark   April 15, 2014 at 11:31AM
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CopFiveO

Awesome... Looks like I've been screwed by my own ignorance. My fault entirely. Awesome

    Bookmark   April 15, 2014 at 11:36AM
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CopFiveO

We'll it looks like it's to late now to fix any of this mess. Guess I just learned an $8400 lesson. I should have known better and done my due dillegence.

    Bookmark   April 15, 2014 at 11:44AM
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CopFiveO

Any recommendations on fixing this mess. Probably just suck it up I suppose

    Bookmark   April 15, 2014 at 11:59AM
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saltidawg

If the installers are still there... you should discuss these issues with the supervisor and also head of the outfit. Get a thermostat that will properly control your HP and Furnace NOW, rather than fighting down the road about replacing it.

Just a homeowner's thoughts.

    Bookmark   April 15, 2014 at 11:59AM
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CopFiveO

Any recommendations on fixing this mess. Probably just suck it up I suppose

    Bookmark   April 15, 2014 at 12:00PM
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mike_home

Did the HVAC contractor do a heating and cooling load calculation? Did you discuss about increasing the size of the furnace and AC? Did the old equipment have difficult maintaining temperatures in the hottest days of the summer and the coldest days of the winter?

    Bookmark   April 15, 2014 at 12:22PM
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CopFiveO

They did not and that is my fault for not researching this stuff enough. The old system did have issues maintaining heat and cooling. But... Again I should have done my due diligence and not made such an expensive mistake.

    Bookmark   April 15, 2014 at 12:40PM
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tigerdunes

If this is already installed and there is no chance of swapping out for correct size, this is my recommendation.

1. Have the 803 thermostat installed.

2. Have high stage of furnace disabled. You won't ever need it.

What if anything are you doing about a filter cabinet for return air?

I'll have to look it up but not sure that's even the correct coil, model and size.

Don't pay dealer any money until this is sorted out.

IMO

    Bookmark   April 15, 2014 at 12:40PM
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CopFiveO

Tigerdunes I'm looking into not paying until my concerns are taken care of to my satisfaction. Just a standard 1" filter for return air.

    Bookmark   April 15, 2014 at 12:45PM
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mike_home

I think the 2 ton AC was probably marginal for your size house. A 2.5 ton should be the right size. However 2-stage condensers only come in whole ton sizes. This may be the reason you got the 3 ton unit. It will operate mostly on the low stages except when you have a very hot day with a lot of guests in your house. The installer should have verified your duct work could handle the air flow required for 3 tons.

I know Columbus has had usually low temperatures this winter due to the polar vortex. I still think the 60K furnace at 95% efficiency would be adequate for house built in 1996. The fact that it is a 2-stage furnace will help keep it for short cycling. You don't want to make matters worse with the furnace by not getting a true 2-stage thermostat.

Don't be too hard on yourself. A good HVAC contractor should discuss all of these items with you and make good recommendations. What you described is what keeps this forum busy with posters.

    Bookmark   April 15, 2014 at 1:06PM
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CopFiveO

Thanks so much for all the help! I know where to go for HVAC questions now... LOL. Now comes the push for the right thermostat. Wish me luck. I'm getting the runaround that "Trane doesn't carry an 803 thermostat. All the numbers are changing". Pushing me towards an expensive upgrade to the XL900 or some new XL624. Thoughts?

    Bookmark   April 15, 2014 at 1:54PM
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mike_home

Here is a link to help you educate your contractor.

Here is a link that might be useful: Trane XL803 Digital Thermostat

    Bookmark   April 15, 2014 at 2:05PM
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tigerdunes

Nonsense. See link.

And just for your info, Trane 803 is a rebadged HW Mdl 8321.

Your dealer is either dumb or just a dealer who is not interesed in his customer.

IMO

Here is a link that might be useful: Trane XL803 Thermostat

    Bookmark   April 15, 2014 at 2:11PM
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CopFiveO

Unfortunately it was our hurry to replace without researching all the options and understanding just how in depth this whole area is. I have newfound respect for HVAC... I think it's more along the lines of, we've got you to make stupid decisions so far what's one more... At this point with so much $ invested and getting hosed on my lack of research and knowledge, I'm standing firm in the whole thermostat thing. It may be stupid on my part after messing the expensive stuff up but it's where I'm at... Guess I have to call Trane because the installer & contractor are not hearing my concerns. They seem to think that the 603 is the appropriate thermostat for this system. I am tending to side with you guys. You have no skin in this game, so to speak. Interested in whether they are gonna control the stages from the board or the 603. I'll see what kind of answer I get.
What about the ComfortR feature? Does that have to be set for the type of AC system installed, via the dip switches? Not just using the factory defaults, correct? I'm getting just enough knowledge to be dangerous I guess.

Thanks very much guys

    Bookmark   April 15, 2014 at 2:50PM
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tigerdunes

Yes, comfort R dip switches have to be set correctly. Factory default will not do.

Quite easy to do if you can read and know what you are doing. Takes about 5 minutes. This is your installer's job, not yours.

And BTW, since you went up in size on your outside condenser, did dealer install new and properly sized refrigerant lineset? I bet I know the answer already.

IMO

    Bookmark   April 15, 2014 at 3:21PM
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CopFiveO

anew line set installed. Seems visually larger.

    Bookmark   April 15, 2014 at 3:35PM
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tigerdunes

Good...but shocked!

    Bookmark   April 15, 2014 at 3:40PM
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CopFiveO

At this point me too... They are cleaning up so I will ask about the Comfort R setting and wether the furnace stages are off the thermostat or off the board on the furnace. I'm betting he will act like he doesn't know what I'm talking about...

    Bookmark   April 15, 2014 at 3:45PM
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