So I have been busy insulating and air sealing areas in my house, namely my fireplace bumpout (which only had Energybrace cardboard sheathing for exterior walls, no insulation) and my porch roof (same as the fireplace bumpout, but at least they put in a little spray foam and batt insulation there).

I live in a 4 story townhouse, 1 air handler/zone. The insulating and air sealing has been paying off as the heat has run less when needed (in Maryland, has not been real cold yet). However, a (bad) cat and less furnace run time has led to an interesting problem. I used to have up to a 15 degree or so temperature difference from the 1st (with the aforementioned fireplace bumpout) to the 4th floor. The heater would run a lot and really warm the 3rd and 4th floors. Now I have a nice 3-5 degree difference from top to bottom. The house feels cooler though since I am not going up to the 80 degree 4th floor anymore, it is more even with the rest of the house (I kind miss waking up toasty warm….).

Here is where the bad cat comes in (and no, not getting rid of the cat). She had a coupe of UTI’s and started peeing in the 3rd floor bedrooms, so we now have to keep the bedroom doors shut to prevent this (she doesn’t pee anywhere else). Each bedroom actually has a supply and return, no return in the hallway though. The returns are undersized I am sure (one is a 2″x 6″ slit in a metal pan with a grill over it, the other is a flex duct that is the same size or slightly smaller than the supply duct). The one bedroom (north facing) now seems cooler than the rest of the house, which I am sure due to inadequate return air duct. With doors open, no issue, but we can’t keep the doors open due to the cat.

So I am looking for a non-destructive idea to provide more airflow into and out of these rooms. i have looked at transfer ducting, etc. as a last resort. I am trying to find a way to slightly prop the door open (and inch or two at most) for air (and not cat) passage. Any ideas? I have thought about putting a hook and eye on each door and frame. That would be minimal disturbance and could be left like that when the room is unoccupied, with the door shut at night while my son is sleeping.

This may not be an issue later in the season when the heat is running more frequently, but it has been noticeable in this fall weather. Just looking for ideas that I may not have thought of.

Thank You,
Neil