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  1. #1
    Join Date
    May 2007
    Northern Virginia
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    Need Help w/New Trane Install questions

    Last week we replaced our 23 year old carrier furnace (125K BTU input ~65% efficiency) and 16 year old 2.5 ton Kenmore A/C with the following in our 3400 sq ft house (main level and basement):

    1) TUD100R9V3K - Trane 80% 2 stage furnace (variable speed)
    2) 4TWX6036B100A - Trane XL16i Heat Pump (w/RXC036S3HPD coil)
    3) TCONT803 - Trane Thermostat
    4) Aprilaire M-700 Poweer Humidifier
    5) Aprilaire 2200 - Media Filter

    I really wish I had found this site prior to making our decision on equipment and install. We didn't get a formal load calculation but I did get several quotes and hope I picked an appropriately sized system (furnace may be a bit oversized) and reputable installer. I'm a bit worried about our install, especially the heat pump, controls, and making sure we get the full capability out of a system that was pretty expensive. In retrospect, I don't think my installer had much experience with this specific setup. He was not in favor of the Trane Fossil Fuel Kit and thought he had previously used 2 outdoor thermostats to control the heat pump and gas furnace.

    I really want to get full use out of at least the most important capabilities of this new system. Any thougths on the following would be greatly appreciated:

    1) Can the TCONT803 really provide good/reasonable control of this system and capabilities?

    2) The TCONT803 allows me to set a balance point for using the heat pump versus gas furnace. We've initially set it to 40 degrees but the T-stat only allows 7 settings (15,20,25,30,35,40,45 degrees). Is not being able to set this more finely a real problem?

    3) The oudoor temp sensor used for determining when to use heat pump/gas furnace seems to be a problem. It is sometimes in direct sunlight and close to brick exterior which also affects temp accuracy (higher and lower at times). Is there a typically good place to locate this sensor? Can/should it be located inside heat pump panel? Or is just out of any sun OK?

    4) How does the TCONT803 control the 2 stage gas furnace? Does it just run the 1st stage for 10 minutes and then kick to 2nd stage? Is this a significant limitation?

    Any thoughts on my current system/install and if I need to change any setup would be much appreciated. Thanks in advance.

  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
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    1. No. Have them install the Vision Pro IAQ. It stages the gas furnace in cold weather and also does dehumidify on demand along with the XV furnace. I just installed it on mine, neat!

    2. You need the 5 degree spread to avoid constant on & off between gas and heat pump. If you set to 40, it waits til 45 to go back to heat pump. On the IAQ, if between the aux lockout and the heat pump lockout, the control will allow gas to come on if temp drops 2 degrees below setpoint. You can set your HP cutout lower.

    3. Have it put on the shady side of the house. I don't like it in the HP control panel, don't think it is as accurate there.

    4. See #1. All the 803 will do is use the timer. I personally think this is quite a limitation on the comfort a 2 stage furnace can provide.

  3. #3
    Join Date
    May 2007
    Northern Virginia
    Post Likes
    Thread Starter
    Thanks for the great info.

    I thought that setting the balance point on the TCONT803 to 40 degrees meant that if the temp was 40 or above, only the heat pump would heat our house. If temp below 40, only the gas furnace would be used. Is that wrong? What exactly does my current 40 degree setting do?

    After reading, am I correct that the Vision Pro IAQ will give the following advantages?:

    1) run my 2 stage gas furnace in a better way (longer time on 1st stage??)

    2) give me more and better control of my heat pump operation/dual fuel operation (does it have a finer balance point setting than 5 degree increments?).

    3) give me a better dehumidification process/control. Does it allow me to set the humidity level and then it will run in some efficient mode to lower humidity without just cooling the house to a lower than set temp?

    We're in the Washington D.C. area. Are the advantages of the Vision Pro IAQ ones that I will definitely notice in efficiency/comfort with my new system? Would you recommend I have my contractor just take out the new TCONT803 and replace it with the Vision Pro IAQ? Will that be very expensive and is it a justifiable expense to get the added capabilities of the Vision Pro IAQ?

    My contractor ran an extra 4 wires (in addition to my original 4 wires) for the TCONT803 install. Is there anything unusual about the Vision Pro IAQ install that would make it difficult for my installer since he may not have installed this setup before? Any specific setup info I could provide him would helpful.

    Thanks in advance for the great help.

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