Do we need fresh air in HVAC system? Kids are continually sick
We've been in our house for 2 1/2 yrs. It's about 2750 sq ft in 2 stories. We have a heat pump with auxiliary elec furnace and the house is divided into 2 zones. The first year, we were not getting enough heat or cool air when needed, and finally when the heat pump had a pressure lock because of a wrong refrigeration amount, the HVAC guy looked around and realized he didn't have a fan setting turned up right to give us good air flow. That solved the lack of warmth and cooling, but at that point, it made the whole system sound like a toy train whistle, as it tried to draw through the ductwork and return air ducts more quickly.
His first response was to turn the fan back down and I explained that wasn't a resolution I was interested in. Then he looked and decided his crew had neglected to put in any fresh air inlet, and he would 'be back the next day to take care of that.' That was 15 months ago. We have spoken to him several times since...One time he swore he'd already been back to do it. The whistling in the ducts seems to have gone away on its own somehow.
Before we fight this any further, I want to know if it's the answer to our problems, anyway. It seems when the kids get colds, they get one after another, and I wondered if it could be due to the lack of fresh air. I wondered if we had a house system akin to that of an airliner that is just recirculating bad air again and again. But, from doing a search and reading previous posts here, it doesn't sound like we're in need of fresh air? I'm sure it's a fairly tight house, but with us home all day most days with pets and kids, the exterior doors are open more than a few times each day.
Someone at work recommended to my husband that we use some disinfectant on the mesh and electronic air filters when we clean them. Anything else you know that might help us?
thanks so much.