Debra’s new house in southwestern Virginia will be a one-story design of 1,344 square feet with half the space devoted to a single, open room and the remaining area divided into two bedrooms, two baths, and a utility room. The main source of heat will be in the open room, and in the absence of a conventional forced air heating system, Debra’s quandary is how to distribute the heat evenly.
Heating loads for this Climate Zone 4A house are relatively modest — about 14,000 Btu per hour. Between small baseboard heaters and leaving doors open, the bathrooms and utility room should have enough heat. It’s getting heat to the bedrooms that’s looking more problematic.
In a post at the Q&A forum, Debra wonders whether low-output bathroom fans can be used for heat distribution.
“We are interested in using a couple of Panasonic bathroom fans to send warm air from the main room to each bedroom, using 6-inch metal ducts going straight about 15 feet (within the building envelope),” she writes. “The fans have adjustable speeds, and at the highest speed of 150 cfm they could change over the air in each bedroom in just 7 minutes (which might be too much).
“Seems like that could do a fairly decent job of evening out the heat between the main room and the bedrooms,” she continues. “I don’t care if the bedrooms are a few degrees cooler, though.”
This simplified heat distribution system would let Debra skip baseboard heaters and programmable thermostats for the bedrooms. But will it work?
That’s the topic for this Q&A Spotlight.
Sorry, the plan won’t work
GBA senior editor Martin Holladay gives Debra two reasons why this is not a good idea.
“The first relevant factor is the specific heat of…