Buildings

Comfort Capacity in a Tri-Level Home

Q: Our family room, which is at the bottom of a tri-level house, sits on a concrete slab. It is open to the kitchen, which is the next level up, and there are two ceiling heating ducts, the typical small ones. The room is too cold relative to the rest of the house. The garage is in the next room. Can I cut two more ceiling openings into the same ducts, but on the other side of the room and experience more heat in the room, so that two ducts have four openings into the same room? The room has a fireplace with a wood-burning insert. What if I got a high-efficiency gas insert to help heat the room? Beyond the initial cost of $1,000 or so, will I be spending a huge amount of money to help heat the room this way?

A: Right now, you're not comfortable because more heat is leaving the room than is coming in. There are basically two ways to deal with this: add more heat to the room or slow down the heat loss from the room. You've already identified two possible ways to add heat to the room: increase the flow of heated air from your central heating system or add a supplementary heater.

In general, cutting more holes into the same duct will simply spread out the amount of air coming into the room — it won't increase it. That's determined by the size of the air handler fan, the size of the duct(s) going to the room, and the length of the ducts. If there are dampers in the system, you may be able to increase the air flow by opening them. If the ducts are leaky-which is typical-you can seal them, if accessible. In many houses, simply sealing the ducts solves problems like yours.

If you can increase the air flow to the room by cutting more holes in the duct, it means you will be robbing air from another room. This is probably not a good plan. If a good HVAC contractor evaluates the system and says you have the capacity to run more air into this space, then you can either replace the existing ducts with larger ones or run an additional duct into the room.

The other choice is to add supplemental heat to the room. This can work. Since you already have a wood-burning insert there, but don't want to mess with wood, the question is whether it provides enough heat to satisfy your needs. If it does, then replacing it with a gas model will also probably work. If the wood doesn't heat the room, then a gas insert may not either, unless its output is much greater than the wood burner's.

At any rate, be sure to get a unit that has tight doors, is vented to the outside, and draws its combustion air from outside. We don't recommend so-called "vent-free" units under any circumstances. You may also want to consider hydronic (fluid-filled) wall or baseboard heaters, radiant wall or ceiling panels, or other supplemental heating systems.

The other approach to improving comfort is to slow down the heat loss from the room. This would involve looking at how well the walls are insulated, including the wall between the room and the garage. Are there leaks where outside air can get into the room, or where heated air can leave? What kinds of windows are in the room? If the surfaces of the room are cold, it's almost impossible to be comfortable, even if "enough" heat is being pumped in.

I've learned from experience that the words "tri-level" and "comfort problems" often go together. The problem is usually in the typical framing details, which often include a double-wall between the mid-level and the other two. This creates an open cavity that connects the crawl space under the middle level to the space between the first level ceiling and the third level floor, the mid-level attic, and the upper level attic.

In other words, there's a good chance that much of the living space is surrounded by outside air. Blocking off this unintended air flow is the first key to getting the house to a place where your husband can sit in his recliner, resplendent in boxers and undershirt in the middle of January, enjoying a cold one and watching large men knock each other around.

In general, it's more cost-effective over the long run to fix the house than to pump more heat into a sieve. Fixing the house will actually improve comfort while reducing your heating bills. Adding more heat may improve comfort, but your monthly bills will go up.