THX9000 Prestige / Dehumidify Help
#1
10-06-09, 03:54 AM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
THX9000 Prestige / Dehumidify Help
I have installed this new fine thermostat to my Goodman Model # AEPT060-00C-1A air handler last weekend. This replaced an old manual thermostat.
I added the common wire from the air handler to the thermostat that was required to make this work.
It seems to be working, but I am unclear how the dehumidification works. I assume this is a 1H/1C system, and I believe that is how I hooked it up using the instruction in the Honeywell manual.
A couple of facts first.
When cooling is activated, the air handler starts up with a slow fan speed.. (In other words this has variable fan speed) I believe this is automated inside the furnace as if I only apply power to Y (compressor contactor), the compressor engages and the fan comes on low speed and eventually to high speed without ever applying power to G (fan relay)
When Y power is removed, compressor does disengage and the fan speed stays up for a few seconds and then slows down and eventually shuts down.
The thermostat is set for dehumidification using AC unit.
So I need to understand how the dehumidification works.. Is it perhaps by varying the fan speed so that the air flow is reduced thus giving a better opportunity to remove humidity?
I assume this is all within a close range of target temperature only?
If my assumption is correct, then I think I may need one more connection and or wiring change and perhaps even a dipswitch setting in the air handler to allow for this operation.
Also, just as a side note the CPH setting of 3 seems to have no effect.. I get several more cycles per hour. I wonder if this might lead to my problem as well?
I will provide more wiring details, photos etc upon request.
Thanks very much in advance.
I added the common wire from the air handler to the thermostat that was required to make this work.
It seems to be working, but I am unclear how the dehumidification works. I assume this is a 1H/1C system, and I believe that is how I hooked it up using the instruction in the Honeywell manual.
A couple of facts first.
When cooling is activated, the air handler starts up with a slow fan speed.. (In other words this has variable fan speed) I believe this is automated inside the furnace as if I only apply power to Y (compressor contactor), the compressor engages and the fan comes on low speed and eventually to high speed without ever applying power to G (fan relay)
When Y power is removed, compressor does disengage and the fan speed stays up for a few seconds and then slows down and eventually shuts down.
The thermostat is set for dehumidification using AC unit.
So I need to understand how the dehumidification works.. Is it perhaps by varying the fan speed so that the air flow is reduced thus giving a better opportunity to remove humidity?
I assume this is all within a close range of target temperature only?
If my assumption is correct, then I think I may need one more connection and or wiring change and perhaps even a dipswitch setting in the air handler to allow for this operation.
Also, just as a side note the CPH setting of 3 seems to have no effect.. I get several more cycles per hour. I wonder if this might lead to my problem as well?
I will provide more wiring details, photos etc upon request.
Thanks very much in advance.
#2
10-06-09, 05:13 PM
Forum Topic Moderator
The humidistat can adjust the cooling airflow to 85%.
Note 5 states: When humidistat is provided cut PJ6. Thermostat opens on humidity rise.
It appears that you will use DHM terminals on your stat and the Hum terminal at your air handler. Jumer R to one DHM terminal and connect the other DHM terminal to HUM.
Note 5 states: When humidistat is provided cut PJ6. Thermostat opens on humidity rise.
It appears that you will use DHM terminals on your stat and the Hum terminal at your air handler. Jumer R to one DHM terminal and connect the other DHM terminal to HUM.
#3
10-06-09, 06:24 PM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
#4
10-06-09, 08:20 PM
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Originally Posted by djmegahertz
I am unclear how the dehumidification works.
If you didn't, then you can add the wire to the board's DHUM from the t-stat DHUM2. And you have to cut a jumper on the board.
So I need to understand how the dehumidification works.. Is it perhaps by varying the fan speed so that the air flow is reduced thus giving a better opportunity to remove humidity?
I assume this is all within a close range of target temperature only?
Also, just as a side note the CPH setting of 3 seems to have no effect.. I get several more cycles per hour. I wonder if this might lead to my problem as well?
What is the model # on the unit? how big is your home, and where are you from?
#5
10-07-09, 03:58 PM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Jay,
Thanks for the reply.
I have not yet hooked up DHUM2 to the air handler. Just doing the research.
I have Model # AEPT060-00C-1A air handler. I am in South Florida (Deerfield Beach) and have a 2000 sq foot home.. I do have some heat load to consider though. 5 computers, three large flat screens, two persons, two cats, two refrigerators in the house. So this is a 5 ton air handler, but a 4 ton outside compressor.
There really is not real humidity problem, today it is 53% inside the home, but I would like to take advantage of humidity control since I have put some $$ into this THX9000 Honeywell thermostat.
As for the CPH, what I am noticing is that the temperature say set at 77 will always stay at 77. Never goes up or down, therefore the system seems to cycle more often.
Unless this thermostat is faking me out somehow.. It seems as it is maintaining a +/- 1 degree max.
So unlike my last thermostat, where it would go up and down 2-3 degrees, it just seems to cycle too much.
I am just concerned that these 6-8 cycles per hour I am seeing will cause premature damage..
I would have thought that this high tech thermostat would have had a setting to allow a little wiggleroom.
It is a scroll compressor, so I think it can take it, but just a thought.
Thanks for the reply.
I have not yet hooked up DHUM2 to the air handler. Just doing the research.
I have Model # AEPT060-00C-1A air handler. I am in South Florida (Deerfield Beach) and have a 2000 sq foot home.. I do have some heat load to consider though. 5 computers, three large flat screens, two persons, two cats, two refrigerators in the house. So this is a 5 ton air handler, but a 4 ton outside compressor.
There really is not real humidity problem, today it is 53% inside the home, but I would like to take advantage of humidity control since I have put some $$ into this THX9000 Honeywell thermostat.
As for the CPH, what I am noticing is that the temperature say set at 77 will always stay at 77. Never goes up or down, therefore the system seems to cycle more often.
Unless this thermostat is faking me out somehow.. It seems as it is maintaining a +/- 1 degree max.
So unlike my last thermostat, where it would go up and down 2-3 degrees, it just seems to cycle too much.
I am just concerned that these 6-8 cycles per hour I am seeing will cause premature damage..
I would have thought that this high tech thermostat would have had a setting to allow a little wiggleroom.
It is a scroll compressor, so I think it can take it, but just a thought.
#6
10-07-09, 07:42 PM
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Originally Posted by djmegahertz
As for the CPH, what I am noticing is that the temperature say set at 77 will always stay at 77. Never goes up or down, therefore the system seems to cycle more often.
Is there a vent near the t-stat?
Unless this thermostat is faking me out somehow.. It seems as it is maintaining a +/- 1 degree max.
#7
10-07-09, 07:53 PM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Good point, and yes, I did have a vent near the TStat at one time, also next to the air intake, never understood that one.. I have since closed that vent off as it served no purpose. So that concern is no longer an issue.
I moved the CPH from 3 to 1.. I will let that run till the weekend and will report back the findings.
Thanks again..
DJ
I moved the CPH from 3 to 1.. I will let that run till the weekend and will report back the findings.
Thanks again..
DJ
#8
10-07-09, 08:01 PM
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Yeah, if you have a vent blowing on/near the t-stat, it going to throw it off on you.
Will be waiting to hear back from you later on..
Have a great week!
Will be waiting to hear back from you later on..
Have a great week!
#9
10-08-09, 06:14 PM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
I got home early today and decided to try this now.
I cut the jumper and added the NC relay contact from R to HUM on the fan control board in the air handler.
Works perfectly! When I trigger the humidity, the fan does slow down. And once it gets above 5% threshold, it then returns to normal speed. Thanks to all that helped guide me to this proper hookup.
The only issue left is the too many cycles per hour. I still see the thermostat staying exactly to the temperature I set it to. Example if it is set to 77, it will never go to 76 or 78. The system is making sure it will stay at 77..
My old thermostat would go to 76, cut off, and then move up to 78 and as it reached 79, it would come back on..
Any ideas what might be wrong with this one? I would find it hard to believe that this only has a 1 degree variable?
I cut the jumper and added the NC relay contact from R to HUM on the fan control board in the air handler.
Works perfectly! When I trigger the humidity, the fan does slow down. And once it gets above 5% threshold, it then returns to normal speed. Thanks to all that helped guide me to this proper hookup.
The only issue left is the too many cycles per hour. I still see the thermostat staying exactly to the temperature I set it to. Example if it is set to 77, it will never go to 76 or 78. The system is making sure it will stay at 77..
My old thermostat would go to 76, cut off, and then move up to 78 and as it reached 79, it would come back on..
Any ideas what might be wrong with this one? I would find it hard to believe that this only has a 1 degree variable?
#10
10-08-09, 06:17 PM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Oh, I just recalled the mention of setting it and leaving it for a few days.. I will do that and see if this corrects itself later.
#11
10-08-09, 07:46 PM
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Originally Posted by djmegahertz
Example if it is set to 77, it will never go to 76 or 78. The system is making sure it will stay at 77..
My Honeywell is 5 years old, and been very pleased with it, and I don't feel the "Swing" in temp changes as I had in the past with the old t-stat that did swing.
#12
10-10-09, 05:33 AM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
So am I just being too concerned then? Is this normal operation or perhaps in the next few days, the stat will make adjusments to the run times?
Thanks again
Thanks again
#13
10-10-09, 05:44 AM
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes
on
0 Posts
You may be over concern, but if the system is still cycling on and off often (6 to 8 times), can be a couple of things.
-System over sized
-Low load
-False reading from near by vent
You said earlier there was a vent blowing on it, and closed that off.
-System over sized
-Low load
-False reading from near by vent
You said earlier there was a vent blowing on it, and closed that off.
#14
10-10-09, 12:13 PM
Join Date: Oct 2009
Location: Florida
Posts: 11
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Yes, there was once a problem with a nearby vent, I closed that off completely a few years ago, and that stopped my excessive cycling issue I had with the last thermostat..
I even had another odd issue that I finally figured out around the same time..
The vent caused the thermostat to get cool readings and shut off too soon.
Then once it did shut off, some airflow from the garage was making to the stat from the rear as there was a hole where the stat wire was coming through. The hole was about 3 inches in diameter.. I sealed that off and all was finally good..
Now with this new thermostat, I seem to have the cycling too much again..
Today is a hot day, so it is not doing so bad.. About 2 cycles in the last hour.
But in the evening after the sun goes down, that is when I notice it more. I get up to about 5-6 cycles an hour.
So you might say that I maybe a little oversized, that was my choice as I needed the system to work with my heat load requirements, but in the evening, I perhaps need only 3 ton..
My next unit will be a two stage, and that should fix the problem all together.. I plan to hang on to this one for another 3-4 years (it is coming up to 5 years old now) and then upgrade to a new 2 stage system.
I even had another odd issue that I finally figured out around the same time..
The vent caused the thermostat to get cool readings and shut off too soon.
Then once it did shut off, some airflow from the garage was making to the stat from the rear as there was a hole where the stat wire was coming through. The hole was about 3 inches in diameter.. I sealed that off and all was finally good..
Now with this new thermostat, I seem to have the cycling too much again..
Today is a hot day, so it is not doing so bad.. About 2 cycles in the last hour.
But in the evening after the sun goes down, that is when I notice it more. I get up to about 5-6 cycles an hour.
So you might say that I maybe a little oversized, that was my choice as I needed the system to work with my heat load requirements, but in the evening, I perhaps need only 3 ton..
My next unit will be a two stage, and that should fix the problem all together.. I plan to hang on to this one for another 3-4 years (it is coming up to 5 years old now) and then upgrade to a new 2 stage system.
#15
10-10-09, 06:25 PM
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes
on
0 Posts
yeah, a two stage would be an ideal system for you.
I have a two stage gas furnace, and LOVE it.. The house is comfortable on cool days like to day (35˚) it runs on first stage, and when it gets down to 0˚, it runs almost non-stop on first stage, then when it below -10˚ then 2nd stage starts cycling on and off. The coldest I've seen is -20˚, and I am guessing when it's -25˚, then 2nd stage would stay on all time.
I have a two stage gas furnace, and LOVE it.. The house is comfortable on cool days like to day (35˚) it runs on first stage, and when it gets down to 0˚, it runs almost non-stop on first stage, then when it below -10˚ then 2nd stage starts cycling on and off. The coldest I've seen is -20˚, and I am guessing when it's -25˚, then 2nd stage would stay on all time.
