Installing humidifier on a Bryant 373 LAV Downflow System
#1
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Installing humidifier on a Bryant 373 LAV Downflow System
Hello everybody. Great forum you have here. Glad Yahoo led me to it. I want to install a humidifier on my furnace, since the winter here in Boie Idaho has been pretty cold this year, and the lack of humidity is killing my sinuses. I bought an HE260 from Home Depot. But when I went to install it, I found out it was too large.
Here are a few pictures of my furnace:


If you look at the top of the furnace where the plenum connects, you can see I only have a small amount of space available to mount the humidifier. Specifically I have a space that is only 13" high x 18" wide. And the Honeywell HE260 is taller than that.
So here are my questions:
1. Am I mounting this in the correct place?
2. If so, are there other humidifiers that will fit here instead?
3. Can I power and control the humidifier off of the furnace (Bryant 373 LAV) itself? Or do I need a seperate transformer and sail switch?
4. Do they make a combo thermistat/humidistat? Or do I have to add seperate control unit?
Finally, there is also a piece of duct that runs into the return, but I don't know what it is. You can see it here:

I saw a post about a fresh air intake. And I thought maybe this is what this was? But I also see there is a damper to close it, so I wasn't sure. Any help would be appreciated.
Here are a few pictures of my furnace:


If you look at the top of the furnace where the plenum connects, you can see I only have a small amount of space available to mount the humidifier. Specifically I have a space that is only 13" high x 18" wide. And the Honeywell HE260 is taller than that.
So here are my questions:
1. Am I mounting this in the correct place?
2. If so, are there other humidifiers that will fit here instead?
3. Can I power and control the humidifier off of the furnace (Bryant 373 LAV) itself? Or do I need a seperate transformer and sail switch?
4. Do they make a combo thermistat/humidistat? Or do I have to add seperate control unit?
Finally, there is also a piece of duct that runs into the return, but I don't know what it is. You can see it here:

I saw a post about a fresh air intake. And I thought maybe this is what this was? But I also see there is a damper to close it, so I wasn't sure. Any help would be appreciated.
#2
Thanks for the great photos.
Yes. how much room do you have down below the A/C coil?
Steam. Honeywell is coming out with a new steam model that is going to be great, but may not get out till Feb. or March....
Yes, you can control it off the furnace's board.
Yes, Honeywell IAQ t-stat. but it may be an overkill for your set up being that you habe a single stage system.
It could be? I see it going up into the attic.... Have you gone up and see where it went to??
2. If so, are there other humidifiers that will fit here instead?
3. Can I power and control the humidifier off of the furnace (Bryant 373 LAV) itself? Or do I need a seperate transformer and sail switch?
4. Do they make a combo thermistat/humidistat?
Finally, there is also a piece of duct that runs into the return, but I don't know what it is. You can see it here:

I saw a post about a fresh air intake. And I thought maybe this is what this was? But I also see there is a damper to close it, so I wasn't sure. Any help would be appreciated.

I saw a post about a fresh air intake. And I thought maybe this is what this was? But I also see there is a damper to close it, so I wasn't sure. Any help would be appreciated.
#3
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Jay,
Thank you for the quick response. To answer your questions and add a few more of my own:
If the A/C coil is that big silver box directly under the furnace, then I have even less room there than on top of the unit. The duct work I have access too on the bottom is only 11" tall at that point.
But I thought I'd seen posts on here that say the steam systems will rust out a furnace very quickly. I keep seeing that a bypass system is the best option. Is that not the case? Or is this new system different? How much would it cost for a system sized for a 2100 sqft house in a climate like Boise ID? We're pretty hot in the summer, but dry. It's high desert here. During the winter it can get down in the teens, but not much worse. The house is only five years old.
Ok, how would I do that? Is there a diagram somewhere you could refer me to?
Please forgive my complete ignorance, but I know nothing about HVAC systems. What is a single stage system and why would this be overkill? What other options are there?
It's very difficult to get up that area, so I haven't looked. Honestly I didn't even notice the duct work until I was taking the pictures. So I thought someone would just look at it and say "Oh yea, that's a such and such."
Thank you for the quick response. To answer your questions and add a few more of my own:
If the A/C coil is that big silver box directly under the furnace, then I have even less room there than on top of the unit. The duct work I have access too on the bottom is only 11" tall at that point.
Ok, how would I do that? Is there a diagram somewhere you could refer me to?

#4
But I thought I'd seen posts on here that say the steam systems will rust out a furnace very quickly. I keep seeing that a bypass system is the best option. Is that not the case? Or is this new system different?
Honeywell TrueSTEAM is something new, and can order them online.
How much would it cost for a system sized for a 2100 sqft house in a climate like Boise ID?
Ok, how would I do that? Is there a diagram somewhere you could refer me to?
Please forgive my complete ignorance, but I know nothing about HVAC systems. What is a single stage system and why would this be overkill? What other options are there?
My furnace, it's a two stage furnace, at first stage it runs at at 37,000 BTU for mild days, and temp maintance in the winter.. RIght now, we are at about -5, furnace ran pretty much steady to provide the warmth and comfort, every room is even in temps, and blower is running very quiet. The furnace is about 6' away from be down here in the family room, and I don't hear it running. As the temp dropped over night down to -20, the 2nd stage(Full amout of BTU) kicks in every now and then to help out 1st stage. OTherwise, from temp set back, 2nd stage kicks in to help recover, once it get nears set point ti go back into 1st stage.
So ideal behind two stage heating with a two stage t-stat is quietness, and COMFORT.
The Honeywell IAQ t-stat does the following things.
-Can control up to 4 stage of heating (Use two on mine)
-Can control up to 2 stage of cooling (Use one on mine)
-Can control humidififer. (Have it on mine)
-Can control humidity in summer to help dry out air.(Our summer is humid, and my blower is variable speed and the IAQ can tell the blower to slow down to dry out the air)
-USe of outdoor sensor to control back up heat in heat pump, control humidity level in the winter, or just to see how cold it is outside)
-Can contro fresh air damper, or air exchanger system (Have damper system on my fresh air)...
It's very difficult to get up that area, so I haven't looked. Honestly I didn't even notice the duct work until I was taking the pictures. So I thought someone would just look at it and say "Oh yea, that's a such and such."

#5
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Is this the item you mentioned earlier that will be available in a month or two?
What are the major differences between the TrueIAQ and the Vision Pro IAQ?
But how does eveything tie together?
How do I know if my blower is variable speed?
And what would the fresh air damper do for me?
Thanks again for all of your help.
The Honeywell IAQ t-stat does the following things.
-Can control humidity in summer to help dry out air.(Our summer is humid, and my blower is variable speed and the IAQ can tell the blower to slow down to dry out the air)
-USe of outdoor sensor to control back up heat in heat pump, control humidity level in the winter, or just to see how cold it is outside)
-Can contro fresh air damper, or air exchanger system (Have damper system on my fresh air)...
IF it turns out that is fresh air, you could add the fresh air damper can use the IAQ t-stat, or the control that comes with the damper system.
-Can control humidity in summer to help dry out air.(Our summer is humid, and my blower is variable speed and the IAQ can tell the blower to slow down to dry out the air)
-USe of outdoor sensor to control back up heat in heat pump, control humidity level in the winter, or just to see how cold it is outside)
-Can contro fresh air damper, or air exchanger system (Have damper system on my fresh air)...
IF it turns out that is fresh air, you could add the fresh air damper can use the IAQ t-stat, or the control that comes with the damper system.
And what would the fresh air damper do for me?
Thanks again for all of your help.
#6
What are the major differences between the TrueIAQ and the Vision Pro IAQ?
But how does eveything tie together?
How do I know if my blower is variable speed?
And what would the fresh air damper do for me?
#7
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Jay,
Thanks for all your help a while back. It's been a while, but I'm finally getting back into this project. I've done a lot of research and I just wanted to make sure I'm getting what I need to make this work.
I'm starting with the 9 gallon TrueSTEAM Humidification System, which looks like it comes with the Vision Pro IAQ thermostat (model #YTH9421C1002). Then since I can't mount it right on the duct work, I was going to get the TrueSTEAM 10-Foot Remote Mount Kit. I also want to bring in fresh outside air occaisionally, so I was looking at the EARD6 Economizer Automatic Round Damper. Will all of this work ok in conjunction with my current system above?
If so, what outdoor sensor do I need to make the system automatically adjust for temperature and humidity changes?
And am I correct in understanding that all of the controlled equipment connects to the Equipment Interface Module, and the thermostat and module connect via just a few wires?
I know the Vision Pro IAQ is a little overkill since I just have a single speed and single zone system, but I like the ability to have everything run from one control unit.
Thanks Jay!
Thanks for all your help a while back. It's been a while, but I'm finally getting back into this project. I've done a lot of research and I just wanted to make sure I'm getting what I need to make this work.
I'm starting with the 9 gallon TrueSTEAM Humidification System, which looks like it comes with the Vision Pro IAQ thermostat (model #YTH9421C1002). Then since I can't mount it right on the duct work, I was going to get the TrueSTEAM 10-Foot Remote Mount Kit. I also want to bring in fresh outside air occaisionally, so I was looking at the EARD6 Economizer Automatic Round Damper. Will all of this work ok in conjunction with my current system above?
If so, what outdoor sensor do I need to make the system automatically adjust for temperature and humidity changes?
And am I correct in understanding that all of the controlled equipment connects to the Equipment Interface Module, and the thermostat and module connect via just a few wires?
I know the Vision Pro IAQ is a little overkill since I just have a single speed and single zone system, but I like the ability to have everything run from one control unit.
Thanks Jay!
#8
Welcome back! Glad to help.
Yep
You'll want the Honeywell C7089U outdoor sensor.
Correct, From the touch screen to EIM just needs 3 wires.
Will all of this work ok in conjunction with my current system above?
If so, what outdoor sensor do I need to make the system automatically adjust for temperature and humidity changes?
And am I correct in understanding that all of the controlled equipment connects to the Equipment Interface Module, and the thermostat and module connect via just a few wires?
#9
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
I see I also need 18/2 thermostat cable to extend it beyond the five feet of cable it comes with. Is there anything special about thermostat wire? Or can I use just about any 18/2 wire?
Also, any reccomendations for where to buy this stuff on-line? Becuase of Honeywell's lack of support for the homeowner, I'd hate to be shafted by the seller as well.....
Finally, what is the difference between an EARD6 damper, and an ARD6 damper, besides the price?
Thanks.
#10
Nope, Looking at the specs on this.. "Application: Outdoor sensor for Chronotherm IV thermostats "
If you did use this, and say the temp is 40˚, you would be reading about 25˚ on the display.
The Chronotherm IV is an older style t-stat, that is not made anymore.
What wire were you thinking of using?
I've used this company and had good luck with them.
ARD6=Powered Closed
EARD6=Powered Open
We want powered open.
If you did use this, and say the temp is 40˚, you would be reading about 25˚ on the display.
The Chronotherm IV is an older style t-stat, that is not made anymore.
I see I also need 18/2 thermostat cable to extend it beyond the five feet of cable it comes with. Is there anything special about thermostat wire? Or can I use just about any 18/2 wire?
Also, any reccomendations for where to buy this stuff on-line? Becuase of Honeywell's lack of support for the homeowner, I'd hate to be shafted by the seller as well.
Finally, what is the difference between an EARD6 damper, and an ARD6 damper, besides the price?
EARD6=Powered Open
We want powered open.
#11
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Just plain 18/2 stranded wire.
#12
So is that a makeup air intake, or a fresh air intake?
And what is the purpose of the manual damper? Is there any reason to put an automatic damper on here?
I have this on my system drawing fresh air, and i know I don't have to worry about indoor air pollution.
Just plain 18/2 stranded wire.
#14
Just as long you are about 8' from an exhaust, it can go anywhere.
You can get a 6" vent hood at any Home Centers. Just make sure the vent hood has a screen on it.. not a flapper (range exhaust) on it.
You can get a 6" vent hood at any Home Centers. Just make sure the vent hood has a screen on it.. not a flapper (range exhaust) on it.
#15
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Ok, I've got the water and steam lines, the drain lines and the unit itself physically installed.

Now I need help with the wiring. Besides the 120VAC, I'm pretty confused as to how these items all go together, so that I choose the correct wiring schematics. I have the following equipment (links are to installation manuals):
Bryant 376C Downflow Furnace
Picture of current wiring connections in furnace
Honeywell Truesteam 9 gallon Humidifier Unit
Honeywell Vision Pro IAQ Thermostat
Honeywell Vision Pro IAQ Equipment Interface Module
Honeywell C7089 Outdoor Sensor
Honeywell F300 Electronic Air Cleaner
Honeywell EARD6 Powered Damper
I'd like the steam unit to be able turn the fan on whenever it needs, instead of being dependant on the furnace running all the time. I'd like the thermostat to automatically adjust for outside air temperature to help decrease fogging on the windows. I want the electronic air cleaner to be on whenever the fan is running. I want the damper to open and allow fresh air/make up air when needed.
To the best of my knowledge I don't have a physical airflow switch.
The air cleaner seems easiest, as it looks like I can use a couple of insulated spade conectors to tie it to the EAC-1 and EAC-2 connections on the furnace control board, and that will provide 120 VAC any time the furnace is running.
But not being an HVAC tech, trying to figure out how all of the rest of this goes together is above my head. So hopefully someone can help me out. Thanks!
Now I need help with the wiring. Besides the 120VAC, I'm pretty confused as to how these items all go together, so that I choose the correct wiring schematics. I have the following equipment (links are to installation manuals):
Bryant 376C Downflow Furnace
Picture of current wiring connections in furnace
Honeywell Truesteam 9 gallon Humidifier Unit
Honeywell Vision Pro IAQ Thermostat
Honeywell Vision Pro IAQ Equipment Interface Module
Honeywell C7089 Outdoor Sensor
Honeywell F300 Electronic Air Cleaner
Honeywell EARD6 Powered Damper
I'd like the steam unit to be able turn the fan on whenever it needs, instead of being dependant on the furnace running all the time. I'd like the thermostat to automatically adjust for outside air temperature to help decrease fogging on the windows. I want the electronic air cleaner to be on whenever the fan is running. I want the damper to open and allow fresh air/make up air when needed.
To the best of my knowledge I don't have a physical airflow switch.
The air cleaner seems easiest, as it looks like I can use a couple of insulated spade conectors to tie it to the EAC-1 and EAC-2 connections on the furnace control board, and that will provide 120 VAC any time the furnace is running.
But not being an HVAC tech, trying to figure out how all of the rest of this goes together is above my head. So hopefully someone can help me out. Thanks!
#16
Member
Join Date: Jan 2009
Posts: 20
Received 0 Votes
on
0 Posts
Can't find how to creat new post.
Sorry question for Jay...can't find the icon for new post...my
question is my units General Aire does not shut off when heater turns off....I just replaced the selenoid which solved the problem of no water comming out of unit....can someone tell me how to post this question correctly???
Sorry again
chicagolaure
question is my units General Aire does not shut off when heater turns off....I just replaced the selenoid which solved the problem of no water comming out of unit....can someone tell me how to post this question correctly???
Sorry again
chicagolaure

#17
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
LOL, nice thread hi-jack.....
Make sure you are logged in (Near the top of the screen you will see a little mesage that says "Hi (username)" if you are logged in), then go to Humidifiers and Dehumidifiers - DoItYourself.com Community Forums and look for the big blue button near the top of the page labeled "New Thread".
Chris
#18
Now I need help with the wiring.
EIM to T-stat is easy.. 1-1 2-2 3-3.
Wire hook up.
EIM-----------Furnace-------A/C
Y1----------------Y-------------Y
C-----------------C-------------C
W1---------------W
R*----------------R
*= Leave the jumpers in place
Then wire hook up of TrueSTEAM.
T/S-----------EIM
Hum----------Hum1
Hum----------Hum2
Gt--------------G
Gf-------to furnace's G
follow the dip switch setting.
Fresh air vent.
Vnt1 jumper to one of the R's.
Vnt2 to one of the wire on the vent motor.
Other wire from vent motor to C on EIM.
The air cleaner seems easiest, as it looks like I can use a couple of insulated spade conectors to tie it to the EAC-1 and EAC-2 connections on the furnace control board, and that will provide 120 VAC any time the furnace is running.
#19
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Thanks for the reply Jay.
Yes, I have a "T" and a P-trap on the steam line. For the P-Trap I just used the 3/4" steam line coming off of the bottom of the T, and did an S shape turned on it's side. It's kind of difficult to see in the picture because it runs behind the furnace, but it's there. I still need to get some small brackets to screw it to the side of the furnace to hold it in place permanently. And I just plumbed the P-Trap and the drain line into the condensate line for the AC coil.

When you say "*= Leave the jumpers in place" and "follow the dip switch setting", what do you mean?
Yes, I have a "T" and a P-trap on the steam line. For the P-Trap I just used the 3/4" steam line coming off of the bottom of the T, and did an S shape turned on it's side. It's kind of difficult to see in the picture because it runs behind the furnace, but it's there. I still need to get some small brackets to screw it to the side of the furnace to hold it in place permanently. And I just plumbed the P-Trap and the drain line into the condensate line for the AC coil.

When you say "*= Leave the jumpers in place" and "follow the dip switch setting", what do you mean?
#20
There is a factory jumper on the EIM, I've seen people take them out or they fell out when they try to wire up the EIM.
As for dipswitches, I ment the one on the TrueSTEAM.
As for dipswitches, I ment the one on the TrueSTEAM.
#21
Member
Thread Starter
Join Date: Jan 2008
Location: King County
Posts: 11
Received 0 Votes
on
0 Posts
Ok, I just finished getting this whole thing installed. It's late, so I'll get some pics up later. The Vision IAQ installation manual leaves out the installation programming codes that need to be changed to tell the thermostat their is a humidifier in the system. But I figured it out after a while.
The humidifier is now running (it's will produce steam and there aren't any error codes), the thermostat appears to be working (will heat and cool, and no error codes), but the fan doesn't come on properly when the humidifier is running. And when I try to run the fan manually from the thermostat, it won't turn on either. But it will run when I turn the heat setting up high enough to turn on the furnace. Or if I turn the cooling setting low enough to turn on the AC.
Looking at the wiring diagrams, it looks like you're telling me to use the diagram at the bottom of page 13 of the Honeywell Truesteam 9 gallon Humidifier Unit. If that is correct, shouldn't I also have the wire running from R on the Truesteam, to R on the EIM? Could this be causing the fan not to run correctly?
And now that I've played with it for a little bit, I'm wondering what the big difference is between the wiring diagrams at the bottom of page 13, and top of page 14. Wouldn't page 14 be better, since this way the thermostat controls everything? Or am I understanding this incorrectly.
Also, looking at the dip switch settings on page 16, the option at the very bottom seems best to me. But can this be used without the airflow switch? But at least this way the Truesteam won't operate unless it sees power from the fan.
The humidifier is now running (it's will produce steam and there aren't any error codes), the thermostat appears to be working (will heat and cool, and no error codes), but the fan doesn't come on properly when the humidifier is running. And when I try to run the fan manually from the thermostat, it won't turn on either. But it will run when I turn the heat setting up high enough to turn on the furnace. Or if I turn the cooling setting low enough to turn on the AC.
Looking at the wiring diagrams, it looks like you're telling me to use the diagram at the bottom of page 13 of the Honeywell Truesteam 9 gallon Humidifier Unit. If that is correct, shouldn't I also have the wire running from R on the Truesteam, to R on the EIM? Could this be causing the fan not to run correctly?
And now that I've played with it for a little bit, I'm wondering what the big difference is between the wiring diagrams at the bottom of page 13, and top of page 14. Wouldn't page 14 be better, since this way the thermostat controls everything? Or am I understanding this incorrectly.
Also, looking at the dip switch settings on page 16, the option at the very bottom seems best to me. But can this be used without the airflow switch? But at least this way the Truesteam won't operate unless it sees power from the fan.
Last edited by Sparhawk; 01-12-09 at 12:25 AM.
#22
Here are the settings I'd suggest.
172-1
174-1
176-1
180-0
220-3
240-3
280-1
342-1
370-1
372-3
374-1
379-1 (When done programing it, set dehumidity level to 45%)
383-3
384-1
400- it's up to you, I have ours at 2.
401- count the bedroom that is used all times.
402- figure the main floor area, not basement, unless you use that area a lot.
403-160
404-50
405- it's up to you, I have ours at 2
406-1
the fan doesn't come on properly when the humidifier is running. And when I try to run the fan manually from the thermostat, it won't turn on either. But it will run when I turn the heat setting up high enough to turn on the furnace. Or if I turn the cooling setting low enough to turn on the AC.
Is G wired on EIM to G on furnace?
I'm wondering what the big difference is between the wiring diagrams at the bottom of page 13, and top of page 14. Wouldn't page 14 be better, since this way the thermostat controls everything? Or am I understanding this incorrectly.
Page 13, the TrueSTEAM turns on the fan, page 14 the IAQ turns on the fan.
Also, looking at the dip switch settings on page 16, the option at the very bottom seems best to me. But can this be used without the airflow switch?