Close heat vents in basement or leave open during winter?

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Nimrod1911

Member
Nov 13, 2012
50
I have read many articles that suggest you should NOT close vents in unused bedrooms and close the door. (ie: isolating the unused bedroom, trying to save heat) The furnace will do much better if you leave all the vents open. Some articles indicated that it depends on the system and that some systems could possibly benefit from closing some vents....but most would not. BUT, what about this scenario. I have a rambler where the main floor is 2300 square feet and the basement is 2400. The stairs are located in the center of the home. I can close a door at the bottom of the stairs. I have historically kept the vents closed in the basement during the winter. It is finished and fully insulated and I often have a wood stove burning down there, but am I making the furnace work harder by closing the vents? Would I save money on natural gas and on wear and tear if I opened the downstairs vents as well. (
 

seige101

Minister of Fire
Mar 25, 2008
622
Western MA
I would say it makes sense to close the vents off in the basement if you are not using it or are using another heat source down there. I would think you would save gas by closing the vents off, less area the furnace is trying to heat.
 

HVAC_Marc

New Member
Nov 14, 2014
44
Springville, NY
while you might (and that's a very small might) save some fuel/energy, the costs of cleaning up mold/mildew and other problems from a lack of airflow will cost more than the fuel saved. most times when you have supply vents, there are also returns. if you run a wood stove down there the heat can be circulated thru out the home by utilizing the furnace fan. this will save on gas costs.
 

begreen

Mooderator
Staff member
Nov 18, 2005
82,934
South Puget Sound, WA
Closing off 50% of the capacity of the supply duct is not a good idea. The system is balanced to a determined static pressure. Closing the vents changes this reading causing the blower fan to run faster. That can add extra wear and tear on the motor bearings.
 

moey

Minister of Fire
Jul 12, 2012
1,455
Southern Maine
Does your blower adjust to maintain the correct static pressure? Modern ECM blower?

Is there a damper to close off? Otherwise you may just be leaking air everywhere along the line. The net effect being nothing.

You heat the air in the basement whether you have vents there or not stack effect the air is pulled up to the rest of your house.
 

HVAC_Marc

New Member
Nov 14, 2014
44
Springville, NY
even if it is a modern ecm blower, it doesnt mean he will have the correct static pressure. the ecm control reads amps and rpm, not static pressure. it can guess based on these variables and if any one is too much out of range it will shut down. but it hardly maintains SP, in fact, there are many failures of these ECM motors due to improper SP and airflow.
 

ironpony

Minister of Fire
Jan 22, 2010
2,069
mid-ohio via St.Croix USVI
also the basement is usually part of the building envelope, so allowing it to cool will effect the rest of the house. there probably is a return air vent down there somewhere. if the floor ( ceiling of the basement) is insulated it may not be part of the envelope, which would have less effect. if the floor is uninsulated the floor will be cold from the basement being cold, because it is part of the conditioned space. builders tried this in the 80s to save heating cooling costs, did not last long.
 
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