We have an older home with an efficient heating/cooling system. Temperatures are fine during the winter with little fluctuation between the first floor and the family room in our walk-out basement. However, during the summer when the temperature upstairs is tolerable (73 degrees or so) it's freezing downstairs. Last summer I closed all but one outlet in the basement, hoping that our ducts would carry more cool air upstairs. But the result was that our a.c. coils froze up. Reworking our ducting and/or installing a second thermostat is both beyond our finances and/or expertise. We have intake vents in every room upstairs but only one in the basement family room, right next to the furnace/ac.

Well, if your system is freezing up after closing one register, I would say that the ductwork is under sized. The only thing I can tell you would be to add a register or two upstairs. This really isn't very hard to do. What is your ductwork made of? Fiberglass, metal? Give us the model and serial numer off the furnace, and how many registers you have , and what size they are.

Try letting your fan run continuously. You will need to check your filters more often, but it certainly will keep the home more comfortable. The continual moving air will balance the temperature, and should make the air conditioning compressor run less. That being said, if your return air is noisy, it may not be something you want to live with. But you need to make that decision.

I still think something is undersized, no way should the system freeze after closing one register.

It may seem painfully obvious, but do you have a way to completely block off the access to the basement?

I know some people leave the door to the lower level open all the time.

This allows all the hot air in the basement to rise to the upper level while at the same time allowing the cool air to settle in the lower level.

If you can seal off the access to the lower level, it will help to some degree.

I still think someting is undersized, no way should the system freeze after closing one register.


I don

I still think someting is undersized, no way should the system freeze after closing one register.


I don`t believe he said after closing one register,, think he said he closed all but one, if this helps