We are switching to a 95% sealed combustion Lennox G71 furnace and one of the suggestions I just got today was to install (add) a so-called shotgun cold air return.

Essentially, this would be a cold air return vent located between the existing 8x24 cold air return ducting and the inlet to the EAC for our downdraft system.

The furnace is located in an unconditioned laundry room between the garage and family room. The idea would be to either install a louvered door between the FR and laundry or add a couple of wall vents between the FR and laundry. The shotgun return would then pull air from this end of the house, and the existing cold air return, located up near the top of the stairs to the 2nd story, would pull air from the upper floor and living room area.

We tried to simulate the condition today by just opening up the EAC and letting it draw air from the laundry. It didn't seem to make any more noise and the exisiting vent still was drawing air, but was much quieter.

One advantage of this system would be a warmer laundry room in the Winter. With the existing setup it can get a bit chilly in there during the Winter if the door is always closed.

One disadvantage is the possibility of more noise in the FR... but the G71 should be very quiet. If it doesn't work out we can just remove the vent at the furnace and put a plate over it. The lower level is undergoing remodeling and most of the walls are open so it should be fairly easy to add vents if we decide this is a viable option.

What do you think... worth a try? The other option is to add a cold air vent under the staircase, but that's a lot more work and expense and may not be any better beacause both high and low returns would be in the same area of the house.