New HVAC system install - humidity question


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Old 09-22-08, 07:05 PM
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New HVAC system install - humidity question

I just got a new Lennox system installed today. I got G60UHV furnace (dual stage, variable speed), XC14 A/C, and Honeywell IAQ thermostat. The install went pretty smoothly, but I'm not 100% sure if the techs hooked up the thermostat correctly as I saw them studying the installation manuals for a little too long.

I've had the A/C running for about 3 hours after they left and while the temperature has reached the set 74F, the system is off but the humidity is showing as 49% while it's set to 45%. Isn't the IAQ thermostat supposed to run the A/C at lowest speed blower setting until the desired humidity level is reached?

I haven't gone through the thermostat settings myself yet, but I'm wondering at this point if it's the wiring or the programming issue.

Thanks!

--Rob in VA
 
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Old 09-22-08, 07:20 PM
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it can be either or.

First for starter, pop the cover off the EIM (equipment interface modular) and see if there is any wire hooked up on the left side that has DHUM1 and DHUM2.

If nothing is hooked up to that, then he did not wire it up.
 
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Old 09-22-08, 07:46 PM
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Aha! Nothing is hooked up to the D1/M2 terminals on the H (middle) terminal leads. According to the EIM installation manual D1 is supposed to be jumpered to R and M2 is supposed to be connected to the Low Speed Fan. I also noticed that he only connected W1 (Heat stage 1). Am I only running in 1 stage heat mode, or does the furnace logic determines if the 2nd stage should kick in?

Thanks,

Rob
 
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Old 09-22-08, 08:01 PM
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*eyes rolls* You get a very nice IAQ stat, and the dealer didn't wire it up to get full use out of it?

I'd be making a phone call to get them back.

The furnace may be very well be running 2nd stage from the board (timer), and that not not the best comfort..

W2 should be wired up and board should be set to run on a two stage stat.

Do you have a humidifer?
 
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Old 09-22-08, 08:50 PM
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Originally Posted by Jay11J
Do you have a humidifer?
Yes I do - an existing Aprilaire 400A that I installed last winter. And that's another issue. They hooked it up as a non-powered unit, so I don't think it's gonna ever turn on. They removed the existing Aprilaire controller, 24V transformer, and the outdoor temp sensor. I noticed something was up when they run a drain line to it even though it doesn't need the drain line. When I tried to explain to them that this one doesn't continuously run on water they looked at me funny. Anyway, They did a pretty good install otherwise. The wiring and integration with the existing ductwork seems pretty decent. They definitely did not rush and took their time. I'm very happy how the system looks - just not so sure that's it's been optimized to its full potential. And that's why I'm here so I can ask intelligent questions when I call them up tomorrow am.

Thanks!

--Rob
 
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Old 09-22-08, 09:59 PM
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Originally Posted by Puchatek
They hooked it up as a non-powered unit, so I don't think it's gonna ever turn on.
The 400 is a non-powered unit.. Did they run a wire from one of the R's down to HUM1, and then HUM2 to the humidifier? (other humidifier wire to COM)

They removed the existing Aprilaire controller, 24V transformer, and the outdoor temp sensor.
The IAQ can provide power if it's wired up as above. Did they add an outdoor senor to the IAQ? (Don't have to have it, but it's nice to have... I have it on mine)
 
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Old 09-23-08, 10:00 AM
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Side question.

With the variable speed motor running low to get rid of humidity faster, how does it run the fan slow enough to not get the a-coil freezing up?
 
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Old 09-23-08, 10:09 AM
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Ideal to have a TXV valve on the A/C coil to help prevent that from happening.

The blower speed on most brand drops down to 80% speed vs 100% speed.
 
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Old 09-23-08, 10:30 AM
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Originally Posted by Jay11J
Ideal to have a TXV valve on the A/C coil to help prevent that from happening.

The blower speed on most brand drops down to 80% speed vs 100% speed.
Ah, that makes sense now. So the condenser (compressor) keeps pumping the same, but the expansion valves only releases correct amount of liquid.

So are systems with the TXV valve less efficient? It sounds as if they are wasting energy in order to not freeze up the coil.
 
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Old 09-23-08, 11:12 AM
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Originally Posted by joe1234
Ah, that makes sense now. So the condenser (compressor) keeps pumping the same, but the expansion valves only releases correct amount of liquid.
Correct.


So are systems with the TXV valve less efficient? It sounds as if they are wasting energy in order to not freeze up the coil.
No, it increase efficiency and performance. How or why?

A fixed metering device has no control, and on a high load, the coil may not have enough liquid to boil off to remove the heat, and then the superheat is higher, and the compressor is running hotter, and working harder to run.

TXV controls the superheat allowing the coil to do it's full job with the right amount of liquid into the coil to remove the heat, and the cool gas is able to help cool the compressor and longer life and better efficiency.
 
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Old 09-23-08, 12:09 PM
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Originally Posted by Jay11J
The 400 is a non-powered unit.. Did they run a wire from one of the R's down to HUM1, and then HUM2 to the humidifier? (other humidifier wire to COM)
I'll have to check tonight. Busy day at the office...

Originally Posted by Jay11J
The IAQ can provide power if it's wired up as above. Did they add an outdoor senor to the IAQ? (Don't have to have it, but it's nice to have... I have it on mine)
Yes, they used my existing outdoor temp sensor.

Returning to the W1/W2 issue... How exactly does the thermostat determine when Heat2 is needed? Why is it better than the timing algorithm that the furnace employs?

--Rob
 
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Old 09-23-08, 08:43 PM
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Sorry for not getting back to you right away, a day off today, and been out and about doing things before the storm came in tonight.

Originally Posted by Puchatek
Yes, they used my existing outdoor temp sensor.
Are you getting outdoor temp reading on the stat? From what I understand, the outdoor sensor has to be a Honeywell matching sensor, not another brand, otherwise, the reading is off.

Returning to the W1/W2 issue... How exactly does the thermostat determine when Heat2 is needed?
On the IAQ there is 2 ways the stat will decide if 2nd stage is needed.

-Room temp is lower than set point.
-When first stage has reach it's 80% capacity.


Why is it better than the timing algorithm that the furnace employs?
This furnace has no algorithm at all, just a timer... It's a fixed 10 minutes (or 15).

Give you this ideal here..

Timer;

You come home to a cold house, and you calls for heat. The furnace fires off in 1st stage, and you are wanting heat "now", and you have to wait 10 minutes for it go into 2nd stage.

Two stage stat.

The furnace will fire off right away in 2nd stage and you are getting your extra warmth right away.


or

Timer;

A cold winter night, the furnace runs 2nd stage after the timer has run out, and then the temp has met it set point and shuts down... Could lead to cool spot some where in the house.

Two stage;

Furnace run 1st stage majority of the time, and if the stat sees that 1st stage can't keep up, it will fire off 2nd stage to help out, and runs that 2nd stage long enough to help out, and drops back to 1st stage providing soft even heat all over the house.



My parents has a two stage furnace, and had a single stage stat and furnace ran on a timer... The furnace didn't run long enough to really warm up the basement family room.. (cycle on and off) and I upgraded them into the 2 stage stat, and now the furnace runs much longer in 1st stage allowing the basement to warm up to more comfortable temps.

I have a split level house, and all the rooms up and down are with in =/-1˚ from each other with a nice long run time in our cold -20 winter nights.


Oh I was going to ask, where are you out of?
 
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Old 09-23-08, 09:52 PM
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Thank you for explaining that, it is very helpful.

I have a 2 stage Trane Furnace, but a single stage thermostat.

What is a good 2 stage thermostat - bang for the buck - I don't want to buy one of those that look like a computer
 
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Old 09-23-08, 10:01 PM
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Originally Posted by joe1234
What is a good 2 stage thermostat - bang for the buck - I don't want to buy one of those that look like a computer
Don't want a t-stat to look like a computer?? I am not sure what you mean by that? The VisionPro/IAQ is very easy to program.

Play with this..

In the past when my parents had a programable t-stat, they could never figure it out how to program it, and I upgraded them to the VisionPro, and now mom is able to program it!

Retail model, I suggest the Honeywell RTH7400.

Pro model, Honeywell VisionPro TH8320, or top of the line IAQ YTH9320.

I used to have the VisionPro, and upgraded to the IAQ to control my fresh air damper, humidifier, and dehumidify in the summer.
 
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Old 09-24-08, 05:49 AM
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Jay,

Not trying to hijack this thread but would you be able to help me with my IAQ, DHUM wiring, and an Amana AMV80 furnace? I want to wire up the furnace for dehumidification, but I'm a bit concerned over where the control signal power would be provided from. I know that I will also need to cut a jumper on the furnace board when I wire up DHUM.
 
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Old 09-24-08, 06:34 AM
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Originally Posted by badtlc
I want to wire up the furnace for dehumidification, but I'm a bit concerned over where the control signal power would be provided from.
On the IAQ's EIM (Equipment Interface Moduler) You want to add a jumper wire on one of the R's and bring it down to DHUM1.

Then another wire from DHUM2 on down to the furnace's DHUM/TWIN terminal.

And then cut the "CUT FOR DHUM" wire.

Be sure the advance set up menu is set for dehumdity control up on the IAQ

-----

Be sure to set the jumper to "2 stage thermostat" since the IAQ is a two stage control.. (W2 hooked up)
 
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Old 09-24-08, 07:49 AM
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Originally Posted by Jay11J
On the IAQ's EIM (Equipment Interface Moduler) You want to add a jumper wire on one of the R's and bring it down to DHUM1.

Then another wire from DHUM2 on down to the furnace's DHUM/TWIN terminal.

And then cut the "CUT FOR DHUM" wire.

Be sure the advance set up menu is set for dehumdity control up on the IAQ

-----

Be sure to set the jumper to "2 stage thermostat" since the IAQ is a two stage control.. (W2 hooked up)
I have already done all the other stuff you mentioned for 2-stage t-stat. Is wiring for the DHUM really that easy? I'm scared to death I'm missing something. My contractor had never wired up a system with an IAQ before, let alone for DHUM so I'm really on my own for this.

By the way, what does cutting the jumper do? Does it eliminate the ramping profiles?

Thanks for the help.

EDIT: For the IAQ settings. Is this considered a whole house dehumidifier or just dehumidification through overcooling?
 
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Old 09-24-08, 08:38 AM
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Originally Posted by badtlc
Is wiring for the DHUM really that easy? I'm scared to death I'm missing something.
Yes, it's really that easy. Lot of people make easy thing hard to do! hehe

By the way, what does cutting the jumper do? Does it eliminate the ramping profiles?
I am not sure about Goodman/Amana what that does, all I know it says in the book that it lets the board know you have this control hooked up... Maybe it allows it to ramp up and down as needed than just ramping up to full speed after 8 min.


EDIT: For the IAQ settings. Is this considered a whole house dehumidifier or just dehumidification through overcooling?
In advance set up #379, you want it at 1 "Dehumidify with whole house A/C."

While we are in the menu, go to 220 set it to 2, 240 and 250 set them at 3
 
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Old 09-24-08, 10:06 AM
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Originally Posted by Jay11J
Sorry for not getting back to you right away, a day off today, and been out and about doing things before the storm came in tonight.
No prob. I've had a busy day as well. I have the HVAC tech coming in today to rewire my t-stat. I'll have him check everything. Hopefully he's been trained on the IAQ.

Originally Posted by Jay11J
Are you getting outdoor temp reading on the stat? From what I understand, the outdoor sensor has to be a Honeywell matching sensor, not another brand, otherwise, the reading is off.
Yes, the existing sensor was from my old VisionPro 8000 t-stat, so it's reading correctly.

Originally Posted by Jay11J
Oh I was going to ask, where are you out of?
Vienna, VA (DC suburb) Thanks for your help, I really appreciate it!!!

PS. Last night I also checked the dip switches on the Furnace board, and noticed some interesting settings that are different from the factory default. They have reduced the cooling mode blower speed from High to medium low, and advanced the speed by 10%. (This makes little sense to me) I also noticed the H terminal that provides 24VAC to humidifier was not connected to the EIM. I also wonder if jumper W914 should be cut, as the t-stat is humidity controlling. I'll ask the tech what he thinks about all these settings.

On a side note, do you know anyone who tried replacing the green LED's on the t-stat with blue LEDs?
 
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Old 09-24-08, 10:14 AM
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[QUOTE=Jay11J;

While we are in the menu, go to 220 set it to 2, 240 and 250 set them at 3[/QUOTE]

If it is OK with you, i'll post all my settings in a new thread when I get it done to verify with you.

Thanks again for the help.
 
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Old 10-15-08, 05:14 AM
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Originally Posted by Jay11J
In advance set up #379, you want it at 1 "Dehumidify with whole house A/C."

While we are in the menu, go to 220 set it to 2, 240 and 250 set them at 3
What does setting 220 to 2 do? I know it is first stage CPH, but what is the reasoning? Just to insure longer run times? Should I also set 230 to 2 or leave at 3?

Thanks again. You have been a ton of help.
 
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Old 10-15-08, 06:05 AM
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Originally Posted by badtlc
What does setting 220 to 2 do? I know it is first stage CPH, but what is the reasoning? Just to insure longer run times? Should I also set 230 to 2 or leave at 3?

Thanks again. You have been a ton of help.
Yes, it will provide longer run time if you find that the unit cycle on and off often. My A/C is half ton oversized, and I got mine at 2.
 
 

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