J Pritzen’s single-story Illinois house was built in the 1950s. It’s heated with a gas furnace fully capable of meeting the heating load, but somehow it isn’t getting the job done.
The single-story brick house has a mostly insulated, but unheated, basement. Warm air is distributed on the main floor by a series of floor registers set near exterior walls, and an energy audit tells Pritzen the furnace is cranking out 10,000 Btu more per hour than is lost through the walls and roof.
“Yet it’s not comfortable when the heat isn’t blowing,” he writes in a Q&A post at GreenBuildingAdvisor. “For example, my fingers and feet get pretty cold sitting typing on this computer even though the thermostat is happy.”
Pritzen has taken some temperature readings and discovered warm air is collecting at ceiling height, where it can be 13 F° warmer than it is at floor level. If the thermostat is set at 68°F, Pritzen’s feet will be in 59°F territory. If he could reach up and touch the ceiling, it would be 72°F degrees.
“My baseboard registers simply blow the air up, and most [of the registers] are right up under a window. (Makes me wonder if the heat is just going out the window instead of into the room),” he says. “I was wondering if there are any resources which describe what today’s guidelines are for maximizing forced-air system efficiency by register placement and diffuser selection, in case my home needs an update. For example, is there any reason for a home to really have 48-inch baseboard diffusers? Is that hurting or helping air mixing?”
Pritzen’s heating problems are the topic for this Q&A Spotlight.
Blame the stack effect
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