Greetings all - I'm researching the replacement of my ancient forced-air oil furnace with a new high-efficiency gas model with variable speed blower and 2-stage burner. No AC.
The house is a smallish cape cod style, 850sf main, 250sf single-room finished attic and another 250 semi-finished basement. Portland OR, mild climate.
When the attic was finished, it was supplied with a single duct and no return (although there is an open stairwell which develops a good draft when the furnace is running). Even so, I have to keep the upstairs register partially closed throughout the winter to keep from overheating the attic room (where we sleep).
The question is this - how might the change from the old blower to the new VS blower impact the conditioning of the attic room? If the present, presumably inadequate supply is "more than enough" heat, will the new, (presumably higher-volume? or longer run times at lower volume?) blower reduce or increase this effect?
Anyone care to make educated predictions?
And before you ask, adding additional ductwork to the attic doesn't seem like a viable option, there's just nowhere to put it without major reno work.
Thanks for any input.