Condensation in flu pipe

Reply

  #1  
Old 12-12-02, 06:25 PM
Blademanmp14
Visiting Guest
Posts: n/a
Condensation in flu pipe

I am having a problem with condensation forming in furnace exhaust flu that goes to the roof. It builds up on the cover on the roof and drips back down the duct to the furnace and is leaking out at the bend any ideas on how to stop this would be appreciated.
 
Sponsored Links
  #2  
Old 12-12-02, 07:11 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 9,988
Received 9 Votes on 9 Posts
Question More info please.

Blademanmp14:

What fuel, type of house, type of chimney, length of flue pipe from furnace to chimney, make and model of furnace, age of house, furnace and chimney, outside temp?

Thanx.
 
  #3  
Old 12-13-02, 03:51 PM
Blademanmp14
Visiting Guest
Posts: n/a
GregH: Condensation in flue pipe

GregH the furnace is a Carrier Crusader Gas furnace Model #28rc130010 and is about 8-9 years old.I live in a bi-level home about 25 years old. The flue pipe is approximatly 20-25 feet long,as far as I know it is original with house. From the furnace to the ceiling it is I guess regular duct pipe ,where it goes into the ceiling it looks like it is some type of insulated pipe which extends to the roof. I pulled the flue cap off on the roof and it seems like there is condensation forming on the underside of the cap and dripping back down the pipe. It is about a cup of water a day. Right now the tempature is anywhere between 15 to 40 degrees.If you have any ideas I would appreciate the help.Thanks
 
  #4  
Old 12-13-02, 05:02 PM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,147
Received 0 Votes on 0 Posts
MY THOUGHTS

not familiar with the rectangular vent pipe you describe, is there a mfr name stamped on it? you say the vent is 20 to 25 ft long. how far horizontally, and how about vertically? condensation occurs when the flue gas is cool enough to consensate the moisture it carries. high efficiency furnaces do this as a rule, the flue is actually a drain. i suspect the flue gas is possibly not moving fast enough, have fixed this by replacing single wall pipe with double wall pipe in the past, but not clear on what you have now. also what kind of burner do you have, a long one sticking into the furnace, or small jet type?
 
  #5  
Old 12-13-02, 07:02 PM
Blademanmp14
Visiting Guest
Posts: n/a
hvac4

The furnace has 4 small jet type burners.The flue comes out of the furnace at about a 45 degree angle for about 5 feet going somewhat horizontal. This duct is round and is single wall.It then enters the ceiling into I assume what you call double wall pipe. From here it goes vertical to the roof about 20 feet.My concern is the water is causing the duct to rust and I do not want it to rust through and allow fumes in the house. This happened last year in the winter but I thought we had a leak so I patched with roof cement around the flue pipe ,but now I realize that was not the problem.
 
  #6  
Old 12-14-02, 02:41 PM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,147
Received 0 Votes on 0 Posts
the problem

is in the flue. possibly the inner liner of the double wall rusted out, try putting the blower in a lower speed to keep flue gas temp above dewpoint. i assume it is not rain coming through the cap, i would be sure the tstat does not call for fan at call for heat (switch in elec mode). let us know.
 
  #7  
Old 12-14-02, 07:02 PM
Blademanmp14
Visiting Guest
Posts: n/a
Flue pipe

Thanks for the info I will check in the duct to see if it is rusted out.If so do you know if it would have to be replaced all the way to the roof and if so would any heating/air contractor do this.Is this a expenseive job?Thanks for the info.
 
  #8  
Old 12-15-02, 06:36 AM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,147
Received 0 Votes on 0 Posts
depending on

the location/size of the chase going up, prices will vary, pretty tough job possibly.
 
Reply

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


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: