Installing A Humidifier On Furnace - HVAC - DIY Chatroom Home Improvement Forum
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Like Tree3Likes
  • 1 Post By Bud9051
  • 1 Post By Geochurchi
  • 1 Post By surferdude2
Reply
 
Thread Tools Search this Thread
Display Modes
Old 09-10-2020, 10:35 AM   #1
Newbie
 
Join Date: Mar 2020
Posts: 10
Rewards Points: 20
Default

Installing a humidifier on furnace


Id like to install a humidifier on my furnace before the winter hits. I have a newer Carrier gas furnace with easy access to the main supply duct. My townhouse is about 2000 sq ft. Would the Aprilaire 700 be a good choice?

Also, is there a thermostat that can also work as a humidistat? Currently, I have a Honeywell 9000 series thermostat. I dont see in its specs about acting as a humidistat.
philpalmiero is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-10-2020, 11:02 AM   #2
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,730
Rewards Points: 262
Default

Re: Installing a humidifier on furnace


Hi phil, I can't help answering your question but always like to mention to posters when they have a low humidity issue that the problem is air leakage. Homes generate plenty of moisture but most of it leaks out along with heat you paid for. Air sealing is near the top of the energy improvement list and the savings can help pay for the costs, besides making the house more comfortable.

Story. A home here in Maine was having condensation issues on his new windows. Turned out that the house was built so tight that he needed to run a de-humidifier all winter to keep the humidity low enough the windows would stop dripping. The house was not that exceptional, just well built.

Another note, a typical home replaces ALL of its air every 3 hours along with the moisture it carries. Slow the air leakage and enjoy the house.

Bud
user_12345a likes this.
__________________
I volunteer my help and opinions, but you are responsible for what YOU choose to do with that information.
Bud9051 is online now   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-12-2020, 11:32 AM   #3
Newbie
 
Join Date: Mar 2020
Posts: 10
Rewards Points: 20
Default

Re: Installing a humidifier on furnace


Quote:
Originally Posted by Bud9051 View Post
Hi phil, I can't help answering your question but always like to mention to posters when they have a low humidity issue that the problem is air leakage. Homes generate plenty of moisture but most of it leaks out along with heat you paid for. Air sealing is near the top of the energy improvement list and the savings can help pay for the costs, besides making the house more comfortable.

Story. A home here in Maine was having condensation issues on his new windows. Turned out that the house was built so tight that he needed to run a de-humidifier all winter to keep the humidity low enough the windows would stop dripping. The house was not that exceptional, just well built.

Another note, a typical home replaces ALL of its air every 3 hours along with the moisture it carries. Slow the air leakage and enjoy the house.

Bud

Bud,

Thanks for the advice. My townhouse was built in 1993. I have no idea what R-rating insulation is in the outer walls. My place definitely needs new windows, which I cant afford right to replace right now. Last year, I replaced the weatherstripping around the outer doors. My sliding doors are new, too. What other steps can I take to limit air loss?
philpalmiero is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-12-2020, 11:45 AM   #4
Member
 
user_12345a's Avatar
 
Join Date: Nov 2014
Location: Canada
Posts: 12,469
Rewards Points: 96
Default

Re: Installing a humidifier on furnace


Replacing windows doesn't really save enough energy to justify the cost.

The greatest leakage points - open brick fireplaces with poorly fitting dampers, attic hatches, attic plumbing stack/exhaust fan vents and electrical, basement where the house meets the foundation, window frames. (they can leak more so than the windows themselves)

Some houses need humidifiers and others don't. Depends on how much moisture is coming from the foundation and showering/cooking/breathing/mopping relative to what's being lost.

A house can need a humidifier despite being pretty tight. The best way to measure air leakage is by doing a blower door test, but it's expensive and not worth it unless you're getting an energy audit done anyway for other reasons.
__________________
I am not in the business of any trade I give advice on. I have non-professional hvac experience + good knowledge of theory. Attempt repairs at your own risk. Never jump out safeties - especially pressure switches - on a furnace for testing with fuel supply on; use a meter. Do not troubleshoot with live line voltage present unless there's no alternative.
user_12345a is online now   Reply With Quote
Old 09-12-2020, 01:44 PM   #5
Member
 
Join Date: Nov 2012
Posts: 166
Rewards Points: 332
Default

Re: Installing a humidifier on furnace


Hi, does your utility co. offer any kind of energy audit? that should include a blower door test.
Geo
Bud9051 likes this.
Geochurchi is offline   Reply With Quote
Old 09-12-2020, 03:00 PM   #6
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,730
Rewards Points: 262
Default

Re: Installing a humidifier on furnace


HVAC ducts in the attic outside the conditioned living space.
Insufficient system returns result in excess pressure that forces air out which is then replaced by air in.
And here is a link that discusses more:
https://www.energystar.gov/ia/partne...ide_062507.pdf

Note, a blower door test with an infrared inspection can be less than $100, at least that is what I charged, now retired.


Bud
__________________
I volunteer my help and opinions, but you are responsible for what YOU choose to do with that information.
Bud9051 is online now   Reply With Quote
Old 09-12-2020, 04:27 PM   #7
Newbie
 
Join Date: Mar 2020
Posts: 10
Rewards Points: 20
Default

Re: Installing a humidifier on furnace


Quote:
Originally Posted by Bud9051 View Post
HVAC ducts in the attic outside the conditioned living space.
Insufficient system returns result in excess pressure that forces air out which is then replaced by air in.
And here is a link that discusses more:
https://www.energystar.gov/ia/partne...ide_062507.pdf

Note, a blower door test with an infrared inspection can be less than $100, at least that is what I charged, now retired.


Bud
That document is great if I were building a house. But my house is built with all floors finished. It has no attic cuz I have a loft and peak ceiling. Not sure what you call the ceiling, but it follows the peak of the roof. I hope it is insulated between the drywall and the plywood of the roof. I have no way to check without cutting a hole.
philpalmiero is offline   Reply With Quote
Old 09-12-2020, 05:07 PM   #8
Member
 
Join Date: Nov 2015
Location: Maine
Posts: 10,730
Rewards Points: 262
Default

Re: Installing a humidifier on furnace


Granted that link is all inclusive but since I can't see what you see it gives you a resource to help understand all of the places where leaks can occur. If I ran my blower door and used my infrared camera you would be shocked even though there may not be anything you can do. That drywall hides a lot of sins.

But extract what you can and look for any major air leaks.

Your ceiling would be called a vaulted ceiling and unfortunately what ever is there for insulation is all you get.

If you have any recessed lights where you can probe past them up to the bottom of the roof that will tell you how deep the rafter cavities are. Hopefully you have soffit and ridge ventilation so subtract an inch or two and that would leave the depth of your insulation.

Good luck
Bud
__________________
I volunteer my help and opinions, but you are responsible for what YOU choose to do with that information.
Bud9051 is online now   Reply With Quote
Old 09-12-2020, 07:04 PM   #9
Member
 
Join Date: Aug 2020
Location: NC
Posts: 45
Rewards Points: 18
Default

Re: Installing a humidifier on furnace


The contributors above are giving you good advice!

If you get up there to probe around can lights, you could also use smoke to see if those lights are letting air escape through them. They probably are. Damp/warm air rising escaping through lights is bringing in dry/cold air through leaks at other locations.

GeoChurchi is giving you very good advice.
An energy audit with a blower door test, if done properly, will show you where your house leaks and tell you how much it is leaking. Your local utility is a good place to ask how/where to find the right people to do this. You might save enough energy to pay for the test in one winter season, if you fix the leaks.

In my home I have an Aprilaire 400 humidifier, installed in 2008. I turned it off and disconnected it from its water source in 2009, so that I am positive it is turned off. It was putting out too much humidity causing heavy condensation in the wrong places. (mold is worse than dry air)

ps - the peaked ceiling you describe is commonly called a vaulted or cathedral ceiling

Last edited by AWWarn; 09-12-2020 at 07:21 PM.
AWWarn is offline   Reply With Quote
Old 09-13-2020, 10:35 PM   #10
Member
 
surferdude2's Avatar
 
Join Date: Nov 2019
Location: Southern Illinois, USA
Posts: 2,963
Rewards Points: 932
Default

Re: Installing a humidifier on furnace


My experience is, when it get down around 30 F., heating the house to a comfortable level makes the humidity drop to a point that is troublesome. When it gets down to a RH (relative humidity) of less than 35%, we get indications of blood when blowing our noses and the static electricity is also a nuisance. Skin feels dry and flaky and I've heard that it causes wood furniture to dry out and suffer damage (scare tactic, I'm sure).

I have an Aprilaire 600 and let the duct mounted humidistat control the humidity in the winter under the conditions above. The rest of the year it's turned off manually. I could have opted for the digital humidistat they offer and hooked up the optional outdoor temperature sensor and that would rid me of that manual chore each year. The mechanical humidistat I opted for doesn't have that option.

I have it set at 45% and it only runs when heat is called and the furnace blower is operating. It usually runs the entire heat run blower cycle so in reality the humidistat is just there as a top-set limit that only rarely turns the humidifier off.

Our house is extremely tight and very well insulated. That doesn't stop the sag in RH when heating during days below 30 F. as mentioned above.

It's all understandable when you realize that heating air causes it to expand. The consequences of that expansion are two fold... some of it will be leaked out of the house... you can't make a house tight enough to stop that. And secondly, the remaining air will have dropped in RH since part of the original moisture went out with the expanding air. The remaining grains of moisture (as scientists and ASRAE calls them) are spread through the same volume of air. Therefore, relative to volume, the grains of moisture are farther apart than before the air was heated. That's the definition of RH, in essence, it's the distance the water grains are apart. Interesting enough, when the RH gets above a certain point, we describe that condition as "feeling close" and sure enough, the water grains are exactly that!

I would not advise connecting the humidistat to a smart wall thermostat. Mainly because the duct mounted one works quite well. Secondly, it's not necessary to jack with the setting from day to day under normal conditions.
And lastly, it's not worth the effort and more trouble than it's worth since most systems won't the thermostat wiring to support it.

There are those who will say you need to lower the RH on very cold days or else you will get windows that sweat and possibly walls that develope mold inside. That won't happen if you have the outside temperature sensor installed since it provides the data that the processor in the humidistat uses to bias the setting so there is compensation automatically applied.

<end of novel/saga> HTH YMMV
raylo32 likes this.
__________________
Ah, but I was so much older then...I'm younger than that now

Last edited by surferdude2; 09-13-2020 at 10:38 PM.
surferdude2 is offline   Reply With Quote
Old 09-14-2020, 05:35 AM   #11
Member
 
raylo32's Avatar
 
Join Date: Nov 2006
Location: Maryland (DC 'burbs)
Posts: 2,564
Rewards Points: 2,200
Default

Re: Installing a humidifier on furnace


To keep it short I'll just offer a condensed version of SurferDudes's post. He is spot on. Get either the Aprilaire 600 bypass model or the 700 powered model (I have the 700 and love it). Use the duct mounted humidistat... Aprilaire makes a great digital one... and install the outdoor temp sensor. Then it is like that cooker infomercial... you can pretty much set it once and forget it all winter.

Just an aside for you to consider... these units are flow through and run water constantly at a slow rate when the heat is on and there is a call for humidity. So if you set it up to drain to an air conditioning and/or furnace gravity drain to the outside you will eventually end up with a sheet of ice out there. Alternate drain methods are to take it to a floor drain or condensate pump... or like I did install a tube fitting in a nearby main drain stack cleanout cap. Depends on what you have to work with at your house.
__________________
Live long and prosper.

Last edited by raylo32; 09-14-2020 at 05:40 AM.
raylo32 is online now   Reply With Quote
Old 09-14-2020, 07:27 AM   #12
Member
 
surferdude2's Avatar
 
Join Date: Nov 2019
Location: Southern Illinois, USA
Posts: 2,963
Rewards Points: 932
Default

Re: Installing a humidifier on furnace


I must admit to buyers remorse and if done over would get the Model 700 with the Model 60 digital humidistat and install the optional outdoor temperature sensor. As much as I like to tinker with things, I don't want them dogging me and demanding it.
__________________
Ah, but I was so much older then...I'm younger than that now
surferdude2 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Top of Page | View New Posts