Replies

1. 
   USAnigel | Jan 10, 2008 07:27am | #1

   You should only need a breathing tube for the furnace and an exhaust for same. Don't burn warmed air if you can help it cause then it needs replacing and this works against energy saving.

   If you house is that tight the air could become stale, then a air to air exchanger with heat transfer is used to provide fresh air.

2. 
   Jeff_Clarke | Jan 10, 2008 07:48am | #2

   High efficient furnace = Direct Vent - use concentric vent with intake air directly to combustion.   Otherwise use an HRV (Heat Recovery Ventilator) for tempered fresh air - http://www.trane.com/Residential/Products/AirCleaners/FreshEffects.aspx

   Jeff

1. 
   wane | Jan 10, 2008 04:50pm | #3

   he's not talking about combustion air and exhaust, he's talking about a fresh air supply to the cold air return, which is good.  If you want to be more energy efficient you could install an HRV (heat recovery ventilator) and exchange some bad air for good ..

1. 
   Jeff_Clarke | Jan 10, 2008 05:20pm | #4

   I know what he's talking about but if a furnace or boiler has it's own intake for combustion air the heating plant at least achieves neutral pressure, whereas taking combustion air from the house itself pulls in drafts around doors and windows.

   Jeff

3. 
   freestate1 | Jan 10, 2008 09:52pm | #5

   Perhaps a little outside air ducted into the cold air return system would be beneficial.  The trick is to not overdo it.  Introduce too much outside air and you reduce the suction available to move air from the conditioned spaces back to the furnace, thus reducing circulation. 

   Also, if your house is super tight, once the positive pressure is built up, it has nowhere to go, and you cease to both bring in outside air or circulate it within the house.