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And I recently remember hearing forced air is bad for air quality inside! Did I hear wrong or is there something more to the story like “forced air brings in ou

And I recently remember hearing forced air is bad for air quality inside! Did I hear wrong or is there something more to the story like “forced air brings in outside air, so if your outside air is bad you’ll have trouble”?

Kadin 8y ago
Most residential forced-air systems don't bring in air from outside (intentionally at least). They recirculate the air in the building through the heating/cooling unit (typically a combination updraft furnace with AC evaporator sitting on top). Modern systems (since late 80s, maybe?) have return air ducts so that you get even heating even if interior doors (e.g. bedroom doors) are closed, but older systems may only have one return vent per floor or even just a single one in the house, and depend on gaps under doors and such for return air circulation. Bigger commercial forced-air systems have had exterior air intakes and heat exchanger systems for a while, but are pretty new for residential (I've never seen one in the wild myself).
- gregmac 8y ago
  Heat recovery ventilators [1] are reasonably common in Canada. Most (all?) EnergyStar homes [2] have one, and they includes most if not all the houses I've looked at (or friends have bought) in the past decade or so. I lived in a house built around 1985 that had one, which was R-2000 [3], so they're at least that old. [1] https://en.m.wikipedia.org/wiki/Heat_recovery_ventilation https://en.m.wikipedia.org/wiki/Heat_recovery_ventilation [2] https://www.nrcan.gc.ca/energy/efficiency/housing/new-homes/5057 https://www.nrcan.gc.ca/energy/efficiency/housing/new-homes/... [3] https://www.nrcan.gc.ca/energy/efficiency/homes/20575 https://www.nrcan.gc.ca/energy/efficiency/homes/20575
  - gregmac 8y ago
    Oops, I meant houses that were built in the last ~decade are mostly EnergyStar.
millettjon 8y ago
You can add filters on the blower to clean up the air. Especially important in cities.
- twothamendment 8y ago
  Also important in the middle of nowhere when the clean, forest air turns to smoke each August.

Kadin 8y ago

Most residential forced-air systems don't bring in air from outside (intentionally at least). They recirculate the air in the building through the heating/cooling unit (typically a combination updraft furnace with AC evaporator sitting on top). Modern systems (since late 80s, maybe?) have return air ducts so that you get even heating even if interior doors (e.g. bedroom doors) are closed, but older systems may only have one return vent per floor or even just a single one in the house, and depend on gaps under doors and such for return air circulation. Bigger commercial forced-air systems have had exterior air intakes and heat exchanger systems for a while, but are pretty new for residential (I've never seen one in the wild myself).

gregmac 8y ago
Heat recovery ventilators [1] are reasonably common in Canada. Most (all?) EnergyStar homes [2] have one, and they includes most if not all the houses I've looked at (or friends have bought) in the past decade or so. I lived in a house built around 1985 that had one, which was R-2000 [3], so they're at least that old. [1] https://en.m.wikipedia.org/wiki/Heat_recovery_ventilation https://en.m.wikipedia.org/wiki/Heat_recovery_ventilation [2] https://www.nrcan.gc.ca/energy/efficiency/housing/new-homes/5057 https://www.nrcan.gc.ca/energy/efficiency/housing/new-homes/... [3] https://www.nrcan.gc.ca/energy/efficiency/homes/20575 https://www.nrcan.gc.ca/energy/efficiency/homes/20575
- gregmac 8y ago
  Oops, I meant houses that were built in the last ~decade are mostly EnergyStar.

millettjon 8y ago

You can add filters on the blower to clean up the air. Especially important in cities.

twothamendment 8y ago
Also important in the middle of nowhere when the clean, forest air turns to smoke each August.