EcoRenovator  

Go Back   EcoRenovator > Improvements > Appliances & Gadgets
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 11-18-13, 12:42 PM   #1
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default Adding a dedicated air intake to my furnace

I've been wanting to do this for a while now and I think now is as good a time as any to at least start looking into it a bit more. I also haven't seen anyone else do it and I'm wondering why. In any case, my furnace pulls the air for the burner from my basement. While my basement isn't conditioned it does put negative pressure on the house, pulling in cold outside air, since its exhausting air when the furnace is on. Newer furnaces have a dedicated intake so that this does not happen. I would like to modify my own furnace to have its own dedicated air intake.

First off, is there any reason to avoid this? I'm way out of warranty. Would tampering with the furnace cause insurance issues? I'm guessing yes, but I think I'm still willing to give it a shot.



Here is the setup in the basement. Shown here is my old tank water heater. It exhausts into my chimney which is cut off in the attic. I was thinking of connecting the old water heater exhaust duct up to the furnace. It is a 4" corrugated flue pipe and would go up and pull warmer air from the attic (so a very slight efficiency boost there too). Obviously, all the holes in the furnace sheet metal would need to be sealed up. Some aluminum tape would probably make short work of that. The door (which is off the furnace in the picture), would also need a gasket added. Overall though, not a lot of work...

I wonder what kind of efficiency boost I would see out of this? Any ideas? Other Ideas? Comments? Suggestions?

Attached Thumbnails
Click image for larger version

Name:	house356.JPG
Views:	7463
Size:	172.0 KB
ID:	3654  
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 11-18-13, 12:46 PM   #2
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default

I suppose one concern would be that the existing exhaust fan wouldn't be pulling as much air through a long corrugated intake pipe. I could hook up a vacuum gauge to see what the change is to see how big the effect is.
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 12-06-13, 01:51 PM   #3
doug30293
Too Many Projects
 
Join Date: Nov 2013
Location: georgia
Posts: 91
Thanks: 0
Thanked 6 Times in 6 Posts
Default

My first concern would be making sure you maintain approximately the same intake mass flow rate. You should put a balancing damper at the furnace air inlet. When the system is balanced the damper will neither draw nor exhaust air from the basement. It will also bypass the flue if it fails to provide combustion air.

A fan might be required on the old flue pipe to induce down draft of what you hope will be warmer air. I strongly suggest putting the fan at the top, not the bottom of the flue. Air should be pushed, not pulled, for best fan efficiency.
doug30293 is offline   Reply With Quote
Old 12-06-13, 09:48 PM   #4
Servicetech
Apprentice EcoRenovator
 
Servicetech's Avatar
 
Join Date: Nov 2013
Location: Moore Oklahoma
Posts: 267
Thanks: 108
Thanked 23 Times in 21 Posts
Default

You will never see the difference in your gas bill. Condensing furnaces don't pull much air from the conditioned space like the old natural draft furnaces did. A cheap fart fan exhausts twice as much air as a typical condensing furnace does.
Servicetech is offline   Reply With Quote
The Following User Says Thank You to Servicetech For This Useful Post:
Daox (12-09-13)
Old 12-06-13, 11:22 PM   #5
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,431
Thanks: 431
Thanked 619 Times in 517 Posts
Send a message via Yahoo to jeff5may
Default

Beware of positive pressure!

In winter, any positive pressure inside the house will push warm, moist air into your envelope. This moisture will condense, soaking insulation or whatever occupies the warm/cold boundary. If the supplied moisture freezes, it can cause severe damage to your home in places that are hard to detect. If it doesn't have a way to dissipate, it will remain and grow mold in the cooling season.

This is the major reason most all gas heaters have an exhaust but no real intake. Unless your house is sealed up like a submarine, it doesn't take much pressure to move enough water vapor to cause problems. The manufacturers have learned the hard way not to expose themselves to this liability.

Last edited by jeff5may; 12-06-13 at 11:34 PM..
jeff5may is offline   Reply With Quote
Old 12-07-13, 08:35 AM   #6
Servicetech
Apprentice EcoRenovator
 
Servicetech's Avatar
 
Join Date: Nov 2013
Location: Moore Oklahoma
Posts: 267
Thanks: 108
Thanked 23 Times in 21 Posts
Default

Quote:
Originally Posted by jeff5may View Post
Beware of positive pressure!

In winter, any positive pressure inside the house will push warm, moist air into your envelope. This moisture will condense, soaking insulation or whatever occupies the warm/cold boundary. If the supplied moisture freezes, it can cause severe damage to your home in places that are hard to detect. If it doesn't have a way to dissipate, it will remain and grow mold in the cooling season.

This is the major reason most all gas heaters have an exhaust but no real intake. Unless your house is sealed up like a submarine, it doesn't take much pressure to move enough water vapor to cause problems. The manufacturers have learned the hard way not to expose themselves to this liability.
Virtually all condensing furnaces today have a dedicated intake pipe. No liability issues since the intake/exhaust of the furnace is sealed off from the house.
Servicetech is offline   Reply With Quote
Old 12-07-13, 11:46 AM   #7
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,431
Thanks: 431
Thanked 619 Times in 517 Posts
Send a message via Yahoo to jeff5may
Default

Ok, sorry. I wasn't sure what kind of furnace Daox has. My bad.

jeff5may is offline   Reply With Quote
Reply


Thread Tools
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

Forum Jump


All times are GMT -5. The time now is 02:04 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design