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  1. #1
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411

    Confused VisionPro IAQ Tstat versus 2-Stage Compressor/VS Furnace

    I have a new York 2-stage YZH DFHP with VS, modulating furnace and a Honeywell VisionPro IAQ tstat with a remote EIM at the furnace.

    The contractor asked me how I want the tstat set up. Haven't a very good idea on that. Not sure he does either since he hasn't installed an IAQ tstat before. The IAQ install manual seems to pretty much list a bunch of options and the choices. Doesn't spend a lot of time giving an overview of the whole process and interactions.

    As background, the York diagram in the install manual for a VS or PSC modulating furnace with 2-stage HP says to set up the York tstat to be 3 Heat/2 Heat Pump (don't know what tstat that is but mentions options that sound like an IAQ derivative).

    The contractor initially turned on the AC for a few days with no furnace yet and without much programming. After the initial hours where the DFHP caught up with the 90+ temps in the house due to no installed system, it has basically been running at low blower and stage 1 HP - been cooler since install. It did seem initially that it short cycled in less than 5 minutes but seems to be running much longer now once in a while. Also seems to be dehumidifying to the 50% humidity level that is set. I think this thing is too smart for me even without full programming.

    The IAQ has a lot of "E", for "Auto Discover", option choices. Is that a reliable way to set up the IAQ tstat so it can figure out the best way to control the HP and the VS furnace?

    Here are a couple of questions on some IAQ options:

    0174 "Cooling compressor stages" - "E" OK or tell it "2"?
    0176 "Heat or Heat Pump Aux stages" - "E" OK?
    0200 "Backup heat" - "1" for Fossil fuel?

    0220, 0230, 0240, 0250, 0260 options all have to do with cycles/hour on compressor and heat stages - "E" OK? I don't want short cycles or continuous running.

    Although I couldn't wade through much of the extraneous stuff in the ones I found, maybe there some good threads or links that you guys can suggest to help on setting up these units.

  2. #2
    If I remember this thread over the weekend I will tell you what mine is set to.

    And I am going to talk to the installer about some of the options.

    I have really know thought about the AC option, but on the dual fuel I am going to talk to him about the different fan speeds for stage two.

    I think that the slower is for higher air temps, but lower COP. Being cheap I want to start with the high speed if that is true. Might tweak it later.

    And for the switch over my guesstimate puts it at 35, But I am going to start at 30 see how it works.

    And 3 stage is right. You want 2 stage of HP and the 3rd is the furnace. Don't know you can set the bottom end of the modulating furnace or if it start at the minimum and then ramps up as needed.

  3. #3
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411

    Question No IAQ hints?

    I am really surprised for how many recommendations I have read for the IAQ tstat, that I haven't had any helpful posts. I misstate something?

    This whole CPH thing, especially with multiple stages, seems to be black magic from the threads I have read. Aren't there any definitive threads or links that can be recommended?

  4. #4
    Join Date
    Apr 2008
    Location
    Northwest Arkansas via Chicago Area via Straight Up from There on Lake Superior
    Posts
    1,411

    Better IAQ Manual

    Did a Google search and came up with a much more informative manual written in 2006 for an IAQ with EIM. It is not as abbreviated as those that shipped with my unit. No multiple language stuff, all English. It covers the whole spectrum of wiring, placement, etc. The biggy for me is that the option definitions are better with interactions between different options. And it covers recommended cycles per hour. But maybe not good enough for the HVAC non-wannabe.

    Understand the 2 stages of cooling but still don't understand what the 3 stages of heat are that York recommends. Thought that it might mean compressor stage 1, compressor stage 2 and backup NG VS modulating furnace. But haven't found any explanation that confirms this. Any ideas?

    If interested, see: http://www.forwardthinking.honeywell...ll/68_0287.pdf

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