We just purchased a home built in 2003. One thing we found that I have never seen before is a 8" return air duct work that comes from the outside of the house to the main truck on the return side of the heating A/C unit. The duct work does have a manual damper which I closed for the time being. From what I understand, this is to supply fresh air to house.
1.) When should the damper be open? All year around - summer and winter? Should the damper be slighy open?
2.) Also I found a timer on the side of the heating and A/C unit (ones where you would use on christmas lights). Im not sure what this timer is for.
Thanks John from Ridgefield Washington.