Help - Mid renovation and HVAC is a mess
We are renovating our home. Basically moving the kitchen to a back room and moving some walls. It is a 1940 center hall brick colonial in the wash dc area. We have a single forced air system that covers 4 floors (we have an AC window unit in attic). We are 80% done but running into some problems.
1) the GC was suppose to put in a new entry to the living room from the center hall (by the stairs to basement if you are familiar with center halls). When he took down the plaster, he discovered a mystery duct to the upstairs. He says it is to our master bath upstairs. He wants to charge us $1100 extra to move it as he consider out of scope as it was unknown when he spec'ed the job. No guarantees on how well it will work. He wants to take a supply out of the basement and redirect it thru the hall closet and connect it up into the ductwork leading to the bathroom supply vent.
That supply worked great in the master bath so i'm hesitating as the supply vent in the basement is just avg air output right now and moving it to 2 floors higher would make it worse.
2) We had an air return integrated into our new kitchen cabinetry and it isn't pulling any air. Meanwhile a new supply vent was put in the basement ceilign (didn't tell us this - errrr) and it making this whiny sucking sound because it drawing so much air when the AC system is on. The back house has a single supply (it was an addition) and it is now this one in the kitchen that doesn't work.
How important is it to have this supply working? I have a feeling he is going to balk at fixing this as it isn't straightforward and i don't understand HVAC.
On #1 an alternative proposal we have been considering is putting in a heat pump for the top 2 floors of the house. We were planning on eventually putting in a second zone of AC but it doesn't seem to be much more costly to do a heatpump. We would keep gas for basement and first floor. Do you think this is a good alternative? Then we would forgo the bathroom supply vent and install a heat pump in the attic in the near future.
Thanks for listening and any advice you can give!!!