HVAC Return

shingler

I had a Rheem Heat Pump installed to heat and cool my 2nd and 3rd floors a few years ago. I am not currently using the 3rd floor where the air handler is located and closed the registers supplying that area. I also closed the returns to pull the air from the 2nd floor where it is warmer. My thought being why draw cooler air from the 3rd floor to heat to supply the 2nd floor. While doing this I noticed a 24 x 8 in hole cut in the return duct work right next to the air handler. The area where the unit is located is not heated and most of the return air seems to be coming in from this hole. When I close that off, the unit seems to be working harder (I can hear it is running louder). I am starting to question the install by my contractor.

Is that correct, and do I need leave that return open right next to the unit.

Any info is greatly appreciated!

Bestheating

Let's see... I might guess that you have a boiler on the first floor. Either way, another heat source heating in part, your second floor. Try to think in basic airflow terms to solve your particular situation. Heat and cool are not your issue at this time. It is just the airflow. First, air will take the path of least resistance. This is typically the distance out the shortest runs and back to an available return.
In your case, is the 24x8 in a living area on the 3rd floor, or in an attic access area? Also, make sure that any opening is before the filter and has a grill on it. If the system was properly installed, there should be a damper on each of the warm air runs. These should be used, but the returns are not normally closed off for any reason. Never make the mistake of dampering down the airflow to the extent that the unit is exceed it's rated temperature rise in the heating mode, or freezing up in the cooling. That's all I can offer without knowing more about the system.

HVAC Doc

Cutting off too much return will starve the unit of air. The results in higher head pressures in the winter time in heating mode and low suction pressures and liquid slugging in cooling mode. You may be either short some returns or the unit was sized counting on all the returns being open. How many do you have on each floor and their sizes and what size is your heat pump (tonnage)?

shingler

Bestheating, you are correct. I have an oil furnace on the first floor. I had no heat in the bedrooms on the 2nd floor when I bought the house.

The unit is in an attic access area.

Thanks for the info thus far. I will review and probably reply with another question or two. I will probably need to run some calculations.