Furnace Efficiency

Reply

  #1  
Old 11-14-05, 09:08 AM
Member
Thread Starter
Join Date: Nov 2004
Location: north dakota
Posts: 167
Furnace Efficiency

My natural gas furnace (boiler) in the lower level of my bilevel is about 30yr old.
Since, the flame needs air to burn:
Is it more efficient to draw the 60deg air from the lower level (obviously my house has enough leaks and cracks for a furnace to work),
or, would it be more efficient to draw in 20deg outside air?

With outside air the furnace wouldn't draw 60deg air up the chimney,
but on the other hand, wouldn't the flame be hotter and thus heat the boiler water quicker with the warmer inside air?
SteveS
 
Sponsored Links
  #2  
Old 11-14-05, 04:32 PM
Bonehead's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2005
Posts: 202
Originally Posted by Skramy
My natural gas furnace (boiler) in the lower level of my bilevel is about 30yr old.
Since, the flame needs air to burn:
Is it more efficient to draw the 60deg air from the lower level (obviously my house has enough leaks and cracks for a furnace to work),
or, would it be more efficient to draw in 20deg outside air?

With outside air the furnace wouldn't draw 60deg air up the chimney,
but on the other hand, wouldn't the flame be hotter and thus heat the boiler water quicker with the warmer inside air?
SteveS
That's a very good question that I have actually wondered about myself.

I have supposed that fire is SOOOO hot that it so overwhelms the temperature of the fresh air being drawn in. And because of this, I have a feeling that the fresh air being drawn into a sealed combustion burner would be more efficient.

Any one else?
 
  #3  
Old 11-15-05, 02:33 PM
Jay11J's Avatar
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 18,427
I don't have a fact, but they say in the newer sealed (90%) system, it burners hotter and cleaner when it uses outside air..

The air is cleaner, and don't have the household fumes.. and what not in it.
 
  #4  
Old 11-15-05, 03:08 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389
Wink

There is just so many BTUs in the Gas for heat.No matter where the air comes from. Just keep the burner clean and set the air on the venturi right

ED My .02 cents
 
  #5  
Old 11-16-05, 04:18 PM
Member
Join Date: Nov 2005
Posts: 235
On effiency:

Actually, there would have to be a small increase in temp across the heat exchanger if you were pulling inside air as opposed to outside air due to some of your BTUs would have to heat the cold air up to room temp as opposed to just heating room temp up to whatever, but this would be offset by the amount of outside air that would be drawn into your house due to you venting inside air for combustion.

So in theory maybe, in reality no change.
 
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