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Trane XV80 and Honeywell IAQ setup

Posted by greenjp (My Page) on
Tue, Jul 10, 12 at 7:41

Had our system replaced last week with a 3.5 ton XR13 AC, 80k XV80 furnace, and Honeywell IAQ stat. I was reading the various manuals and looking at the settings (I am a nerd mechanical engineer and like to know how things work) and found a few things that seemed off, wanted to get some insight before the tech comes back later this week for a checkup (the furnace makes a rattling/clunking noise at fan start up). System maintained temp at 75 deg and humidity ~50% during our ridiculous heat of the past few days FWIW.

Dip switches S4-1 and 2 are both set to On and it seems the ComfortR profile is active whenever a cooling call is made.

The IAQ is set up for dehumidify with AC (379=1). The system definitely turns on the AC if the measured humidity goes 5% higher than the setting. Overcooling limit is set to 3 deg (383=3) and this seems to work correctly too. What is not clear is if the wiring is set up correctly to run the blower at the reduced speed for dehumidification. Here's what I see inside the EIM:
From IAQ:
1 - red
2 - white
3 - blue

From EIM:
C - white to compressor, blue to furnace
R (hard jumpered to RC and RH) - red to furnace
W1 - white to furnace
W2 - black to furnace
Y - red to compressor, yellow to furnace
G - green to furnace

All other terminals are unused. At the furnace I see the following:
Y - yellow
W - white
W2 - black
R - red
G - green
C - blue
Neither O or BK are connected, nor are there any jumpers. Based on my research here and elsehwere there should probably be some additional wiring. Per the IAQ manual, in the EIM it seems that R should be jumped to DHM1, which should then be wired to BK in the furnance (also see references in other docs to jumpering R and BK in the furnace which I believe would net the same result). Then per the furnace install guide note 10, "A jumper must be placed between 'R' & 'O' to enable the 'BK' circuit or enhanced mode (ComfortR). This 'R' to 'O' jumper must be in place for humidistat dehumidification and proper blower operation with a two step scroll compressor." Don't have a two step compressor but the note about ComfortR is confusing because it seems to be working without this one. Then per the ComfortR pocket guide (note 2 under "Air Conditioner with Gas Furnace") there should be a jumper between Y and O. Apparently different instructions have me confused

Additionally, some of the dip switches are confusing. Note 9 in the furnace install guide states "...S5-2 switch must be set in the 'Off' position if humidistat is used. The 'S5-2' switch must also be turned to 'Off' when applying an airflow command signal to 'BK'." The S5-2 switch is actually set to On. I guess since the wiring described above isn't there this is "correct" for the time being?

Last, for 2 stage heating - the wiring looks correct per the manuals (EIM W1 and W2 wired to furnace W and W2). Dip switches S7-4 are all Off, so I think that means no 2nd stage heat delay (correct for stat control of this feature?) and the default 90 second heat off delay. But then in the stat, it appears to be set for 1 stage heating - 176=1 and option 250 (CPH for 2nd stage heat) does not appear.

So, it appears that both the dehumidification and 2-stage heating features are setup sorta half correctly, and that while ComfortR is definitely working I saw a few references to jumpers that should be in place that aren't. Any thoughts would be greatly appreciated, want to make sure this thing is set up correctly.

jeff


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