sylvan butler wrote:

clare at snyder.on.ca clare wrote:

Vent free heaters produce COPIOUS amounts of water vapour - a much more
serious issue in most cases thanoxygen depletement or CO concentration.

Except my humidifier (on a humidistat) runs nearly all winter long anyway.
So added humidity from unvented gas heater would not likely be an issue.

It would a help...

I'm thinking in climates where heating is needed (not just to take
the chill off, e.g. southern C.A.) lack of humidity is frequently
more of a problem than too much humidity.

An average 2400 ft^2 US house leaks naturally leaks 0.7 ACH, ie 224 cfm,
much more than ASHRAE's standard of 15 cfm per full-time occupant (which
used to be 5 cfm.) This makes house air very dry in wintertime and makes
the system efficiency of a vent-free heater higher than any vented heater.

A good (IDEAS) Canadian house only leaks 2.5 cfm. With people and green
plants evaporating water inside, it needs DEhumidification (eg mechanical
ventilation) in wintertime.

Nick