I have a split level home. Main floor contains living dining and kitchen. 8 stairs up to top level with 3 bedrooms and a bathroom. Down 6 steps from main level to family room and from there down another 6 steps to fully underground sub-basement.

My last house was a ranch which we liked to keep warm at about 75F or so in the winter. With the thermostat set to 75 in the current split level, the top level must be 90F if not higher. The thermostat is in the dining room next to a sizable window. I just covered the supply vents in the top level but I'm not sure if this is safe/efficient/productive, etc. The bottom 2 levels have electric floor heating in addition to vents from furnace. Furnace is in sub-basement.

Any suggestions greatly appreciated.

4 Answers 4


Usually we have dampers to adjust multi level homes in winter pushing more heat down stairs and less upstairs, if there are no main trunk dampers individual room vents usually have dampers or are adjustable. I never recommend totally closing a duct off because I have seen ducts split and flex line blow off when vents were closed too much. Opening the lower vents and partially closing the upper vents will help.

I have also found that keeping the main fan running in low can also help as the air is moved constantly so the upstairs won't have the heat naturally moving up.

  • Both suggestions are key--flow adjustment and plenty of circulation. I have a four-level home and a harsh climate and this isn't really an issue.
    – isherwood
    Commented Jan 28, 2020 at 16:44
  • Short of new ductwork, Would moving the thermostat to the upstairs location that you want to control be an option since there is a supplemental heat source for the downstairs. ?? If the furnace is due for replacement it might be time to think about a multi zone set up with a thermostat for each zone.
    – Alaska Man
    Commented Jan 28, 2020 at 23:02
  • @alaska man, good question but Just moving a thermostat will cause the opposite problem, cold on the lower floor. Duct work won’t need to be changed. if the registers are fixed they need to be replaced but that is not that expensive expensive. A cheap option I used on a couple of flips we actually used metal foil tape to reduce a few fixed registers , cover some of the area from the back. Verify flow and adjust as needed. Aluminum foil could be used if you press the foil into the register so it will hold until a replacement register can be installed.
    – Ed Beal
    Commented Jan 28, 2020 at 23:40

There's multiple options for keeping the top floor cool. If you can, it may be worth it to look into a separate AC zone for the top level, though this is energy intensive. Window AC units could be another option, as could ceiling fans.


Options I've considered for my system, which is two floors with open stairwell and minisplit heads on both floors:

  1. Reduce air circulation between the floors. May require new doors or walls. In my case, closing the upstairs doors helps separate them from the stairwell so less heat reaches them. Not a complete solution but it helps.

  2. A fan or fans to circulate warmer air back down. I'm experimenting with a temporary/homebrew version of a "return duct"; a fan mounted near the stairwell ceiling upstairs which feeds a length of flexible (dryer) duct down the stairwell to blow into the ground floor. Not elegant but it helps.


Consider getting a wireless thermostat which moves up/down stairs depending on either the time of day or the time of year. This is the cheapest and easiest option. These days you could use a wireless temperature sensor attached to a smart thermostat if you have that, move the sensor instead of the thermostat; you could even get two remote sensors and leave one upstairs and one downstairs and use smart home automation to switch which one controls things by time of day and season.

Better options getting you closer to: When cooling use a return that is upstairs and vents which are upstairs (the vents downstairs aren't super necessary in summer since the cold air will find it's way down). When heating do the reverse.. a return that is downstairs and vents which are downstairs.

There are smart zoning systems that work in a variety of ways at varying prices including smart or dumb baffles which go on the ducts where they attach to your indoor unit. These allow you to change the flow rate per duct run by twisting the baffle control (or flicking a button if they are 'smart'). To properly use this you will need a smarter thermostat with a few remote sensors, or you will have to change the baffle settings seasonally.

Please note that if you don't leave enough duct path open (ie close to many vents/ducts) you will

  • Use more energy
  • Wear out your unit more quickly
  • Void the warranty (they probably won't find out)
  • have a nosier system

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