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  1. #1
    Join Date
    Jul 2006
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    613

    IAQ Tstat question

    BeenThere recommended the

    IAQ YTH9421 Tstat

    I asked the contractor for BT's recomended model. He delivered a VisionPro 8000 TH8320U1008.

    Did I get screwed?

    Will this lower the fan speed in a VS AHU?

  2. #2
    Join Date
    Jan 2004
    Location
    PA
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    68,797
    Not only won't it slow the blower.
    It also can't do cool to dehumidify.
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  3. #3
    Join Date
    Jul 2006
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    613

    Talking

    Quote Originally Posted by beenthere View Post
    Not only won't it slow the blower.
    It also can't do cool to dehumidify.

    I knew that upgraded Amana OD unit could not be free He stated I needed a module for the IAQ, that it controlled other options that I will not have installed with my system, and that it (the 8000) has the dehudification feature. Everything I need.

    I hope you are right, the man will be here in the morning for the install, it will be an interesting, But NICE conversation. Can I show him your responce?

    Sometimes the HVAC industry hidden prices can be hard on a HO. I was quoted a price for a complete system, I gave the contractor the things I wanted based on info from here. I got a quote from several.

    Today, the condenser unit changed. Based on info here, it's an upgrade. The Tstat changed. The contracter said the supplier was out of both items and he UPgraded me for no additional charge.

    How does one know? Short of calling off the install and getting another HVAC company.......and hoping the supplier has the parts....etc, etc

    I'm stuck, the job is scheduled for this weekend and I'm headed out of town next week. I cant leave the family cold. GRR

  4. #4
    Join Date
    Jun 2007
    Location
    Fort Wayne Indiana
    Posts
    46
    Think the deal is with the IAQ you only need three wires to thermostat to operate everything. So you don't have to try and run new stat wire. Most digital stats for heat and cool require 4 wires . Heat pumps take 6 wire.

  5. #5
    Join Date
    Jan 2004
    Location
    PA
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    The IAQ(YTH9421) is the thermostat, and equipment interface module.

    It all comes in one package.

    It can control many things.
    Slow the VS blower, dehumidify on demand, over cool by up to 3 if need be, control a humidifier, control a fresh air vent, fan circ(TH8320 can do fan circ also). Control up to 4 stages of heat, and 2 stages of cool.

    The TH8320, does NOT do on demand dehumidify, it does NOT slow the blower down.

    While the IAQ is a thermostat.
    It is more of a system enhancement, then just a thermostat.

    By using the IAQ, VS blowers can be set to nominal air flow and standard ramp up.
    Instead of setting them to low CFMs and or ramp up slow to dehumidify and waste time at slow speeds when the humidity is low.
    Why wait 8 minutes for full cooling speed when its 90F outside, and the indoor humidity is already low. None, its a waste of electric.

    With the IAQ thermostat. Set the blower to the CFM the home needs, and let it decide when and if the blower needs to slow down, or run at 400CFM per ton.
    If the humidity were to increase while its calling for cooling it will slow the blower.
    If the humidity is low during the entire call for cooling, it will leave the blower run at normal speed.

    Some contractors are leary of it, simply because they haven't installed one yet.
    Others because they are afraid of the wiring.

    You can show him anything I post.
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  6. #6
    Join Date
    Sep 2002
    Location
    Northeast Ohio
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    4,855
    Not too much to add to BT's responce. Be nice but educate your installer. The 3 wire hook up to the stat is what we really like especially when going with an add on HP.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  7. #7
    Join Date
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    PA
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    How is the install going?
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  8. #8
    Join Date
    Jul 2006
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    613

    Smile

    Quote Originally Posted by beenthere View Post
    How is the install going?
    Well, they left, but will be back tomorrow. The physical install looks GREAT, so far. One phsysical install question: The AHU is above the condensor about 10-12 ft. The AHU is mounted on the floor of the attic, with the refrigerant lines running along the floor and conectiong to the evap coil. No loop higher that the AHU coil. Not sure if this is an issue or not.

    One issue to note. the AHU would not fit in my attic access. The guy's had to remove everything from the AHU, bracing brackets and all, to collapse the AHU shell to gain access. We had a real warm day today, the attic was hot, I kept them plenty of cold bottled water and tipped them well at the end of the day.

    The unit is runing in AC mode now, seems OK, but the air volume from the supplies "feel" about the same as the old 2.5 ton unit. There is a 19 degree split right now. COLD air from the supplies.

    They did NOT install the 8000. They left my old one instaled for now. Trust me when I say it was a bit ticklish when I showed him this thread with all of your responces. I kinda regretted it after, the contractor/customer tone came after that.

    I dont think they are comfortable with the Goodman VS electronics and Vision IAQ wiring. I asked them questions about various things about the Tsat interface and stated that when they got the Tstat, they would read the instructions and figure it out, and that AS/Trane was their specialty.

    I have no problem with that, however,

    The condensor contactor chatters when the Tstat is in the heat mode. They trouble shot for a while and said they would bring a new contactor in the morning.

    I just read the instruction booklet and believe I figured out the problem. Without saying much here, there is a paragraph in BOLD that describes this issue. Should be an easy fix. I'll show them the paragraph in the morning.

    Due to scheduling conflicts, they will bring and install the IAQ next weekend. I'm sure I'l be back with more questions about the IAQ interface. They seem to be not familiar at all with this setup.

    Last question, how does this VS work in the factory mode with the dip switches set correctly? No complaints with the VS as of now. It seems NICE.

    Sorry for the winded responce.

  9. #9
    Join Date
    Jul 2006
    Posts
    613

    Hmm

    OK, forget about my last post.....sorta. Due to a warm day, The HP was left in the AC mode. No apparant problem. It got to cold in the house, 69 degrees. The wife got a shower and wanted it warm. Since this is a new install, I dont mind playing AC/heatmode/emergency heat game in one day.

    She switched it to heat. After 15 min, the indoor temp dropped to 68. I went outside and the condensor was running, but the suction line was COLD and sweaty, as one would expect in the AC mode. Turned the heat up 5 degrees, the aux heat LED came on the tstat. Still had 49 degree air from the supply.

    Switched to emergency heat. The condensor shut down. The VS apears to be on full speed, by that I mean it is blowing harder than when it was in the AC mode. You can hear the airflow through my returns, they sound like supplies. The old system never did that. I hope that is not a bad thing. The supply temp after running for 15 min is 79 degrees. The outside ambiant is about 65 degres. My old system, same KW heat strips, read over 100 degrees in the farthest supply.

    I know that he tested the 10K electric strips earlier, you could smell the burn and it took the house up to 81 degrees in about 10 -15 min, that's is why I turned the AC on.

    The installers did trouble shoot the contactor chattering noise after the heat strip test, so who know's what changed. They'll be back in the morning. Did I say they' didnt seem to be sharp on the electronic/electricle side of your buisness.

  10. #10
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    Jan 2004
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    PA
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    There is a factory jumper in the air handler that has to be removed for the heat pump to work in heat mode.

    I'm guessing they don't quite have the indoor unit wired right, since you said it blows more when just in emergency heat mode.

    The lower discharge temp is most likely because the CFM is greater.

    Someone will need to read the install instructions.
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  11. #11
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    Jul 2006
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    613
    Quote Originally Posted by beenthere View Post
    There is a factory jumper in the air handler that has to be removed for the heat pump to work in heat mode.

    I'm guessing they don't quite have the indoor unit wired right, since you said it blows more when just in emergency heat mode.

    The lower discharge temp is most likely because the CFM is greater.

    Someone will need to read the install instructions.

    I have to Agree with you. Look at the time. I've been up close to 24 hrs. I leave for a job trip Monday AM for a week. My family may be left with a mess.
    Yea, I'm loosing sleep over it.

  12. #12
    Join Date
    Jul 2006
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    613
    [QUOTE=beenthere;2723372]There is a factory jumper in the air handler that has to be removed for the heat pump to work in heat mode.

    Thanks BT, I'll pass that on to him in a couple hours.

  13. #13
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    A little reading should provide them with the info they need to correct things.
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