New Install Question / VisionPro IAQ Wiring

[Weaselboy]

http://www.hvac-talk.com/vbb/showthread.php?t=175023

Had my new HVAC system installed Thursday and I have a question about the install of the IAQ. System is Lennox XC16-048 with Lennox G60UHV-60C-090X a five-ton Aspen coil and IAQ t-stat (based on suggestions from above linked thread).

The installer had never put in an IAQ before and spent quite some time perusing the install manual and calling his shop as he wired it up. I see he put in the R > DHM1 jumper like the manual says, but there is no wire from the IAQ module DHM2 connection to the furnace and it looks to me in the manual like there should be one. Figure 16 in the IAQ manual says DHM2 wire goes to "low speed fan" on the furnace, but the installer could not find a connection on the furnace for "low speed fan." From the way I read the furnace install manual it looks like the "DS" connection on the furnace is where the IAQ DHM2 wire should go... is this correct?

Also, shouldn't jumper W914 on the furnace board be cut to allow the IAQ to run things?

I called the company yesterday and they are sending a senior tech out Monday to take a look, but given the company's unfamiliarity with this t-stat I was hoping to help point him in the right direction. The tech on Monday is also supposed to go through all the IAQ installer setup to make sure it is correct (I already checked and it is not).

Would it be best to disable all the ramping profiles in the furnace dips and just let the IAQ handle all this?

The install company has been very responsive and is eager to try out this t-stat and make things right, but I am a little frustrated that the initial install tech just left all the furnace and IAQ settings at default and hit the road. For example, I see the W915 jumper on the furnace board was not cut, so the system is operating only on second stage. Also, I see a 5-4 trouble code flashing in the furnace that indicates reversed polarity and the heater does not work (I assume because of the reversed polarity).

Appreciate any advice.

[RyanHughes]

Would it be best to disable all the ramping profiles in the furnace dips and just let the IAQ handle all this?

That wouldn't be a bad idea so you get maximum airflow on hot days with not so much humidity. When you have days with high humidity, the IAQ will just slow down the blower. Not much sense in slowing down the blower if the humidity isn't high unless you want a quiet startup, which some do. Lennox has several ramping profiles. Do you know what one yours is running?

[Weaselboy]

That wouldn't be a bad idea so you get maximum airflow on hot days with not so much humidity. When you have days with high humidity, the IAQ will just slow down the blower. Not much sense in slowing down the blower if the humidity isn't high unless you want a quiet startup, which some do. Lennox has several ramping profiles. Do you know what one yours is running?

Yes... it is at the default... 30 second ramp up... 7 minutes at 80%... then to 100% if setpoint is not yet met.

[BaldLoonie]

My personal view is let the IAQ handle it. Much of the time you don't need the slow ramp. Why not get full cooling right away then. I know the distant rooms in my house are cooler with the ramp off.

If dhum2 doesn't run to the furnace, he's got it wrong. Not sure what you need to do with any jumpers.

[t527ed]

don't mess with anything and let the lead tech set it up for you.

iaq will not control any ramping profile, it will only slow blower down to control humidity once it is set up right.

i leave the ramping profile controlled by the furnace and dehumidification when needed to be controlled by the iaq.

[beenthere]

I do the same as Baldie does.
Set the blower to stabdard ramp profile, and let the IAQ determine if the blower needs slowed down or not.

First time installing an IAQ can be intimidating for some techs/installers.

Some installers only know how to set up the furnaces/blowers one way because they were never taught other ways.

They're learning, give them a chance.

[bmathews]

Let the senior guy take care of it. A lot of times, install people are just that and can wire basic systems up, but when things get complicated they get in over their head quickly. Not a lot of people buy the nicer stuff, so its a rarity. Don't freak out if the senior guy reads the manual as well. I always read the manual on thermostats, even if I set the same thing up the day before, otherwise you might forget something. Its an outline to follow. Why didn't you buy the Lennox stat designed for your system? I believe it is now the Touchsense stat since the Signature has been discontinued. It does the same thing as the IAQ and is designed for your equipment.

[Weaselboy]

don't mess with anything and let the lead tech set it up for you.

Let the senior guy take care of it. A lot of times, install people are just that and can wire basic systems up, but when things get complicated they get in over their head quickly. Not a lot of people buy the nicer stuff, so its a rarity. Don't freak out if the senior guy reads the manual as well. I always read the manual on thermostats, even if I set the same thing up the day before, otherwise you might forget something. Its an outline to follow. Why didn't you buy the Lennox stat designed for your system? I believe it is now the Touchsense stat since the Signature has been discontinued. It does the same thing as the IAQ and is designed for your equipment.

Thanks guys. Believe me, I have no intention of messing with this myself. I had just hoped to make things easier when the tech gets here Monday. My fear is since this company says they have never used an IAQ before, the senior tech will not know how to wire it up either. I was hoping someone on here with some Lennox expertise could confirm the DHM2 connection from the IAQ goes to DS connection on the furnace? The IAQ manual says to wire DHM2 to "low speed fan" on the furnace, and it is not stated on the furnace board or the furnace manual which connection this is (although I believe it is DS), so I can understand the first tech's confusion.

I went with IAQ based on recommendations here. The latest Lennox t-stat is the Comfortsense 7000 and nobody seemed to know if it had the dehumidify features the IAQ does. On top of that, the install company called me and explained the 7000 came out the beginning of this year and they have already had to replace two... so there are concerns about reliability. They gave me the IAQ at no extra charge, so that coupled with the strong rec. here for the IAQ pushed me to the IAQ.

[catmanacman]

yes dmh2 goes to ds thats what slowes down the blower when in duhumitify and there is a jumper that should be cut by the installer

[Weaselboy]

yes dmh2 goes to ds thats what slowes down the blower when in duhumitify and there is a jumper that should be cut by the installer

Thanks so much for the help. I will let him know.

[Airmechanical]

first thing is first, it needs to be wired properly, that being said;

if it was my system, i would leave the ramping program on, let the IAQ dehumidify when needed

this way you get a nice cold coil on start-up

as well as gaining a little efficiency when compressor cycles off due to the ramp down program!

it ends up being an end user preference issue whether you leave the ramp program abled or disabled!

i live in a semi dry area here in Tennessee, and i still use the ramp program!

i don't have the IAQ, i have the 8000 t-stat coupled with a humidistat

the humidistat slows the v.s. blower down 20% when humidity goes to high for my liking



.

[Weaselboy]

The senior tech just left here and everything now appears to be as it should.

He spent a few minutes reading over the IAQ install manual and the furnace manual, then about 20 minutes tinkering with the wires to make sure he understood what the signals from the IAQ were telling the furnace to do. When he was done he had all the jumpers and wires set correctly and did a full system test as well as verified charge levels.

Once the house cools down and this system drops to first stage, you can hardly hear the blower fan. Exactly what I was after.

Thanks to all here who offered assistance.

[beenthere]

No problem.
Just send $29.95 to each of us.

[Weaselboy]

Rofl :d