Mr. Asthma

Question:

Dear jenwolf, There may be a misunderstanding here concerning the nature of the intake and exhaust.  The "intake to the combustion chamber" may be concentric to the "exhaust from the combustion chamber", like a pipe-within-a-pipe, to reduce the unwanted extra flow through the combustion chamber due to pressure differential (due to wind).  With a differential pressure of zero, the motor that moves the compustion air in and the exhaust out is the only thing that determines the flow of combustion gases, which makes for a perfectly controlled (efficient) burn. The fresh air intake would be a whole separate intake, and probably would be recycled room air only.  The air intake vents for breathable return air are located in different locations and are a different style than the air exhaust vents for breathable air.  Breathable air exhaust vents are smallish and are often in the ceiling or floor.  Breathable air return vents are often built into walls (either a foot off the floor in an 8 foot tall room, or at 8 feet of height in a really tall room), using the wall’s air space between the studs as the tube (how clever). If you would like to talk to people intelligent in the ways of heaters and air conditioners, here is a link to a "Coffee Shop" where real live pros hang out: http://a-1appliance.com/cgi-bin/cs-hvac They probably will not bite your head off.  I’ve asked several questions there and gotten clean away with it. Rich – Hide quoted text — Show quoted text -> > I know it can get tedious and expensive, but try changing your >furnace > > filter once a month and see if that helps. > i wish it were that simple. >Something is wrong with your installation. >A modern high quality furnace will have a separate intake to draw >combustion air from outside – to avoid the possibility of backdraft and >carbon monoxide poisoning. >However, the furnace is supposed to heat and recirculate the indoor air >only. Think about it this way – when it is cold out, do you want to heat >the indoor air from 60