Hi there, I had a contractor install a new set of HVAC 2 years back: - replaced old 85% gas furnace w/ 95% efficiency 60K BTU variable speed 2-stage Heil furnace - installed new Bryant 3 ton legacy single-stage air conditioner + AC coil A few things I'm trying to tackle right now: 1. The blower from the furnace is two-stage. It is capable of handling two-stage air conditioner. The air conditioner however is a single-stage unit. Problem: noisy cabinet. Since the air conditioner is single-stage, the output from the thermostat is connected to the Y/Y2 (2nd stage high-speed fan) input on the furnace unit. The furnace is installed around the corridor corner in a hallway. When the blower pulls air from the vents on both sides of the wall, it's very noisy. I want to reduce fan noise. Idea: I wonder if I can connect the thermostat's cooling switch output to Y1 (1st stage low-fan speed) input on the furnace unit. This way, the blower fan would always be at the lower-speed. This would significantly reduce the noise around the cabinet. The only thing I wonder is whether this would reduce the efficiency of the air-conditioner, as the fan is blowing at low-speed while the air-conditioner compressor is working always at full capacity. Or, it'd just be colder air blowing out slower? Anyone would know? PS: Someone suggested to make another opening in the living room area and lay out a pipe to that spot. The piping would drastically reduce the ventilation noise even at high speed. However, I'd prefer not to make an opening on the floor. 2. There's a leak thru' from the exhaust pipe down to the furnace. In the installation, the HVAC installer used an existing roof vent (cone-shape) by sliding the exhaust pipe into that vent. On the top of the roof vent there is an L-shape PVC pipe he added to direct the exhaust air to point horizontally. I wonder where the water leak is coming from? I never saw this leak from that vent for years--until after he installed the HVAC unit. 3. I am seeing a LOT of dust coming out when I turn on the HVAC unit (heat or AC). I never saw such an enormous amount of dust before with my older furnace. The air ducts are in the attic. The installer did not replace any of the air ducts in the installation. There is an air leak along the edge of the back of the AC coil where it meets the furnace unit. The HVAC installer did not put seal tape along that edge. Would that cause that much dust? The HVAC installer said he was not able to seal that edge up during the installation as it was in the back of the new furnace that he installed. The furnace/AC coil is in a cabinet in the corridor. Thx.