DIYbanter - View Single Post - Why Closing your Air Vents Will NOT Save you Money???

Bob F

Stormin Mormon wrote:
On 1/27/2016 8:13 AM, wrote:
On Wed, 27 Jan 2016 08:06:30 -0500, Arnie Goetchius
My question: Is closing the ducts to three unused bedrooms and an
unused bathroom a bad idea and it won’t save any money on the gas
bill?
Correct You make the furnace work harder and less efficiently by
closing off the ducts unless your furnace is undersized for the home
(which is EXTREMELY rare. Most furnaces are at least 50% oversized

So, if the air leaking out of the back bedroom is
colder since the vent is closed, you still need to
put the same ammount of heat into the house?

Since the air leaking out is colder, it contains less heat energy. The rate it
escapes through the outside insulation will also be lower because the
temperature difference is less. If the inside walls between the heated and
unheated areas were insulated, the losses would be substantially lower, and the
unheated room would be colder. Condensation will likely increase on the windows
in unheated rooms.