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A/c won't shut off unless we turn the system off - honeywell pc8900

A/c won't shut off unless we turn the system off - honeywell pc8900

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  #41  
Old 06-21-16, 05:34 PM
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Thanks. Based on my wiring do you think I got humidifier or not? Let me try to map the wiring and ask you, since I am not still sure what wires goes where on Prestige IAQ. Is my system conventional 1h/1c?
 
  #42  
Old 06-21-16, 09:49 PM
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No, you do not have a humidifier connected to this thermostatic control.
The EIM is wired to bring in cooling on demand for dehumidification.

The Honeywell TH8321R will accomplish everything that your 8900 is doing without the EIM.

Looks like you will also need 5 orange wire nuts where the EIM used to be...

Stat green to equipment green
stat red to equipment red
stat yellow to equipment yellow
stat white to equipment white
stat blue to equipment blue


At the thermostat connect...
green to G
blue to C
white to W1
yellow to Y1

When you get to dehumidify in the configuration select cool with high speed fan.
I usually select overcool up to 1 degree but your existing stat was probably 3 and the new stat will allow you to select 1, 2 or 3 degrees.

Remember to remove power to the furnace before replacing the stat or you can pop a fuse if one is present, or cook the transformer if a fuse is not present.
 
  #43  
Old 06-22-16, 11:45 AM
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Thanks. By equipment below you mean the zone 1 terminals at Mini-Zone panel. Is that correct? Zone 2 wirings at Mini-Zone are connected to tstat from zone 2. So, EIM does not control dampers in my case function without it?

If I am removing existing EIM completely why and where do I need wire nuts? I am just going to use five wires coming from the thermostat. Ain't I?

Where do I connect fresh air ventilation output if I ever decide to use one? There are two wires coming from it to EIM.
 
  #44  
Old 06-24-16, 08:57 AM
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This is my current wiring at Minizone panel. Please let me know. Thanks.

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  #45  
Old 06-24-16, 07:12 PM
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The wire nuts that I spoke of would have been at the EIM.
They would have connected the 1234 wires to the wires going to the minizone panel.

If your thermostat wires are long enough to reach the zone panel then wire nuts are not required.


If you want to control a fresh air damper with only 5 conductors to the stat you will need an EIM.
 
  #46  
Old 06-24-16, 09:14 PM
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Just to make sure I have understood the wiring. So five wires from thermostat will connect directly to Mini-Zone panel at zone 1. Correct? I don't plan to use fresh air ventilation system right now.

Stat green to green @ Mini-Zone panel zone 1
stat red to red @ Mini-Zone panel zone 1
stat yellow to yellow @ Mini-Zone panel zone 1
stat white to white @ Mini-Zone panel zone 1
stat blue to blue@ Mini-Zone panel zone 1

Yes, my 1234 wire is long enough to reach minizone panel.
 
  #47  
Old 06-25-16, 02:33 PM
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The terminals at the zone control board are labeled with letters not colors.

green to G
blue to C
white to W
yellow to Y
 
  #48  
Old 06-25-16, 02:57 PM
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So I do not need to connect the red wire from thermostat to Mini-Zone panel at zone 1, and the new thermostat wires will directly connect to Mini-Zone panel at Zone 1 terminals, is that correct?
 

Last edited by sghimire; 06-25-16 at 03:18 PM. Reason: More info
  #49  
Old 06-25-16, 04:04 PM
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Yes, red to R.

Are you getting the Prestige IAQ?
 
  #50  
Old 06-25-16, 04:12 PM
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Yes thought about the other cheaper one I saw at Costco today but changed my mind I guess to Prestige IAQ you suggested below, TH8321R.

Just the thermostat no EIM.

Seems like wiring is simple now.
 
  #51  
Old 06-25-16, 04:17 PM
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By the way my system would be defined as conventional with 1H/1C. Right?
 

Last edited by sghimire; 06-25-16 at 04:18 PM. Reason: Typo
  #52  
Old 06-25-16, 04:54 PM
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The TH8321R is not a Prestige IAQ. It is Redlink thermostat like the Prestige IAQ. It does not have a color screen.

The Prestige IAQ requires an EIM since it only has R and C terminals. It has a color screen and data logging.

The VisionPro TH8321R can work with or without an EIM.

The VisionPro TH8321 is the multistage Redlink pro model thermostat with humidity control support. The VisionPro is also available as a single stage heat/ single stage cool but without support for humidity control. The single stage TH8110R doesn't even display the humidity in the room.

The existing EIM is not connected to a humidifier. You posted that it is connected to the Y terminal. This tells me that it was wired to bring in cooling on demand for dehumidification. The TH8321R can do this as well. So can the Prestige IAQ.

You have a conventional 1 heat/ 1 cool system.
 
  #53  
Old 06-25-16, 09:44 PM
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Thanks. I got all mixed up

Okay, so for Prestige IAQ's EIM,

R and C from Thermostat Connects to R and C at EIM.
RH, RC and R will be Jumpered at EIM.
W from EIM connects to W at Zone1 at Minizone panel
G from EIM connects to G at Zone1 at Minizone panel
Y from EIM connects to Y at Zone1 at Minizone panel
C from EIM connects to C at Zone1 at Minizone panel

Is this correct?

Where should Fresh Air Ventilator two wires be connected at EIM?
 
  #54  
Old 06-26-16, 08:33 AM
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Connect the fresh air damper to the U1 terminals on the EIM.
 
  #55  
Old 06-27-16, 10:00 AM
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Thanks. Remaining wiring l wrote down below is correct?

Why do we need fresh air ventilation system by the way? What does it do?
 
  #56  
Old 06-27-16, 10:04 PM
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Yes, your wiring is correct.


If you ask a mechanical engineer they might tell you that a fresh air duct piped to the furnace will help keep the house under positive pressure and help replace any air discharged from kitchen or bathroom exhaust fans.

They might say that it is better for the outside air that would reenter the house through the chimney or travel backwards through unused exhaust fans, after a negative pressure condition was created, to enter the house in a location that it could be dehumidified and conditioned before it entered the living space.

The high humidity in Texas doesn't work well with outside air ducts.
The advantage of using a fresh air duct with a motorized damper that is controlled by the Honeywell Prestige IAQ is that you can lockout the outside air if the house is above your setting for the max humidity in the living space. You can also set it to only open the damper 20% of run time.
 
  #57  
Old 06-28-16, 11:22 AM
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Great info. Thanks a lot.

I have DATS currently connected to my minizone panel. Do I need separate DATS connection for my Prestige EIM. I think kit comes with DATS but if I don't need it I would buy and EIM only.

Also, one basic question - why is zone 1 tstat has to be connected to Mini-Zone via EIM and not Zone 2? In my current configuration EIM would control S1, S2 or U1, U2 ...etc based on Zone 1's tstat regardless of the condition of zone 2. Is that right?

If I decide to replace zone2 tstat with Prestige IAQ also, I need all five wires from tstat connected to zone 2 at minizone panel, correct? Assuming I am powering it using the C wire.
 
  #58  
Old 07-01-16, 01:47 PM
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Hi Houston204, would you please let me know.

Thanks.
 
  #59  
Old 07-01-16, 05:27 PM
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I would keep the existing DAT sensor connection to the zone control board. If a damper failed to open it would prevent ice or over heating.

I would also install the two duct sensors to the new EIM.
I run heat and cool for 5 minutes each then set the thermostat to let me know if my system is performing too far over or under these readings.

Since I also purchased the internet gateway it will send this message to my phone. I would then know to try to get home early enough to address the problem.

Would you feel more comfortable if zone 2 controlled the outside air damper? Not sure that I understand this question.
 
  #60  
Old 07-02-16, 06:12 PM
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My question was why would my zone 1 tstat connect to EIM and not zone 2 tstat (which connects to Mini-Zone panel only. Just curious. Sorry for the confusion.

Is there a particular location I need to install these duct sensors? Is it fairly easy?
 
  #61  
Old 07-02-16, 10:49 PM
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Does zone 2 stat even support a fresh air damper?

Would you like zone 2 to control the OA damper?

I drill a 3/8" hole about 18" after the evaporator coil (or air handler) for the 10K supply sensor and another just before the furnace for the 10K return air sensor.
 
  #62  
Old 07-03-16, 09:28 AM
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Thanks. Just to be sure let me send you pictures of the ducts because I am not sure about the location.

What do I use to seal if there is any air leak at the site after the installation?
 
  #63  
Old 07-03-16, 10:04 AM
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The sensors have a gasket. I never need to seal.
I actually use a $17 unibit the I picked up from Home Depot to drill the hole. I am not positive what size that I stop drilling with the step drill bit. The smallest size the fits the probe.

The thermostat will ask you if you have a 10k or a 20k sensor. It is 10k.
I always connect the return air sensor to the S1 terminals and the supply air sensor to the S2 terminals to make it easier to remember when the stat asks "What sensor is wired to the S1 terminals".

I also determine if the OA damper is normally closed or normally open.
Honeywell dampers usually come normally open. They spring open when 24 volts is not supplied. This seems backwards to me but I can see the value in this when the damper is for a supply air duct. If the control breaks you still have air.

You must create a bridge from the R terminals to a U1 terminal.
The remaining U1 terminal connects to one of the 2 damper wires.
The remaining damper wire connects to C.
 
  #64  
Old 07-03-16, 10:52 AM
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I apologize I do not understand this part. Currently my dampers are connected/controlled via Mini-Zone panel. I thought only fresh air ventilation would use U1 terminals and others would remain unused. Can you please elaborate? Thank you.

"....You must create a bridge from the R terminals to a U1 terminal.
The remaining U1 terminal connects to one of the 2 damper wires.
The remaining damper wire connects to C."
 
  #65  
Old 07-03-16, 11:56 AM
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I was referring to the OA damper.

This might help...




If you left click this image it gets bigger. If you then left click the magnifying glass on that page it will get even bigger.
 
  #66  
Old 07-03-16, 01:16 PM
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Thanks. Not sure if my system has this is damper currently installed? Can you tell from the wiring pictures I sent earlier?
 
  #67  
Old 07-03-16, 03:16 PM
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Where do I connect fresh air ventilation output if I ever decide to use one? There are two wires coming from it to EIM.

You posted that you have one....
 
  #68  
Old 07-03-16, 04:14 PM
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You do not have any wires connected to the VNT terminals on the existing EIM.
What were you referring to?
 
  #69  
Old 07-03-16, 09:35 PM
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Let me go to attic and confirm where those two wires coming from the ventilator are connected, or are just left open. So, OA damper means connection to ventilator, right?
 
  #70  
Old 07-05-16, 09:37 AM
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There are two wires coming from the fresh air ventilation system ( it is coming off of a small transformer looking black device on top of the unit). The white wire is connected to common (C) on the left side of the existing EIM and the red one is connected to Green (G) on the right side of the EIM.
As I mentioned earlier, ventilation system is currently turned off.
 
  #71  
Old 07-05-16, 12:25 PM
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Are you referring to an ERV or a damper?
 
  #72  
Old 07-05-16, 12:48 PM
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That's the only two wires that I see coming out of the Fresh air ventilation system to the EIM. What does ERV means? What is OA damper and where is it?
 
  #73  
Old 07-05-16, 01:26 PM
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Post a picture of your ventilation system. A make and model might also be of assistance.
 
  #74  
Old 07-07-16, 03:54 PM
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Meantime, in my current configuration, I noticed my ac is working fine sometimes and not other times these days. If I set humidity to 40, it ran until temp was 70 despite the fact that cool point was 79. The other day I set humidity to 45, it ran until temp was 76 or so. So does humidity setting impacting my ac to run all the time to reach the humidity level I set...more mysteries for me.

Please let me know your thoughts
 
  #75  
Old 07-07-16, 09:48 PM
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The Honeywell Prestige IAQ allows you to set max over cool for dehumidification to 1, 2, or 3 degrees.
 
  #76  
Old 07-11-16, 08:55 PM
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I thought PC8900 would only over-cool by 3 degrees max.
 
  #77  
Old 07-11-16, 10:04 PM
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https://customer.honeywell.com/resou...0s/68-0173.pdf

I don't see a limit to the overcool to dehumidify feature with that model.
 
  #78  
Old 07-12-16, 11:17 AM
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This explains my issue then. It seems to be humidity setting/control related. Thank you so much.

What would you recommend optimal indoor humidity for a house? Is 50% ok?
 
  #79  
Old 07-12-16, 07:32 PM
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I have my Prestige IAQ set at 50% RH but I would set it to 55% or higher with your existing thermostat since it has no max over cool setting.
 
  #80  
Old 07-19-16, 09:58 PM
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Thanks Houston. I think we identified the issue. It was the humidity setting, at least that is what it looks like. It is working as expected since couple days now. I set the humidity to 55%.

Regarding the ventilator system, I still have not gotten a chance to get the model and good picture of it. I will post it since I would still like to know how it will be connected to Prestige IAQ in case I decide to upgrade my EIM in the future.
 
 

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