"Baby, it's cold outside..."

Most U.S. homes use forced-air heat, but I have elected to go with a hydronic (hot water) system.  Forced-air is relatively inexpensive to install, and the ductwork supports air conditioning.  But forced-air is not especially energy efficient.  Modern forced-air furnaces carry high efficiency ratings, but much of this efficiency is negated by leaky ductwork and electricity required by the fan.

A study of over 800 Florida homes found that the pressure created by a forced-air system's blower drives air out through ductwork joints.  This tempered air is lost along the way, and with it one's investment to heat or cool it.  In addition, forced-air systems typically have more supply ducts than return ducts.  This increases positive air pressure inside the house, forcing tempered air out through openings in the structure.  At the same time, negative pressure around return ducts can pull outside air into the house.  Closing doors simply increases these pressure imbalances.  Excessive pressure can also drive water vapor into wall cavities where it may promote decay.  And, in my experience, even if filters are changed regularly, forced-air blows around a lot of dust.

Hydronic systems in a couple of my churches proved very persuasive.  This type of heat was popularized by Frank Lloyd Wright in the late 1940s and was often used in residential construction in the 1950s.  However, leaks due to corroded pipes, as well as increasing demand for air conditioning, made forced-air the system-of-choice for most builders.  I can appreciate the leakage problem.  Parishioners on Grosse Ile, downriver from Detroit, had a major leak in their 1950s-vintage hydronic system.  To correct the problem they had to jackhammer apart and replace the concrete floor under their living and dining rooms.  The advent of plastic pipe in the 1970s reduced the leakage potential and made hydronic a more acceptable alternative, although it still represents less than 10% of the market.  As for energy efficiency, a study of 820 homes in Idaho, Montana, Oregon, and Washington found that ducted homes used 25% more energy for space heating than non-ducted homes.

I will have a small, wall-hung boiler in the crawl space which will supply hot water to baseboard radiators.  This propane-fired unit (no natural gas here) will also heat my domestic hot water.  If all goes as planned, passive solar and the wood stove will carry most of the daily heat load, with the hydronic system coming into play primarily during the wee hours of the morning. •••