I have a 10-year-old home in Blewett that is heated by electric baseboard. Because of the baseboard heat, there is no ducting in the house. There are a couple of drawbacks to this setup:

1.      It wastes heat to ventilate with open windows in the winter, and

2.      As we close all windows when we go on vacation in the summer, it can be very hot and stuffy when we return. Are there any good options to add energy efficient forced air ventilation without resorting to ripping apart walls and adding ducting?

One of the down sides to electric baseboard heat is the lack of air circulation throughout the house. As well as the drawbacks you mention, the lack of air circulation within the building envelope and the lack of fresh air introduction from outside often causes mould and mildew on windowsills and wall surfaces.

There are a couple of ways to get air moving in a building, but ducts are hard to avoid. Here are a few ideas. If you live in a two-storey house with a basement, there is always a “stack effect” or hot rising air pushing through the highest ceiling in your home. You can capture this heat at the top of the highest ceiling by installing an extraction fan. Then pump the captured heat back down to the basement or a lower floor through one or two small ducts. Or, consider a combination of short feeder ducts from this fan to interior wall stud cavities that you have prepared by cutting out the bottom and top plates. This strategy re-cycles hot air that would be lost through the attic and roof, and it creates airflow throughout the interior building envelope.

Another alternative has been dubbed “the poor man’s ventilation system”. It installs simply but does not recover heat. It goes like this. Install an interval timer that is programmed with 2 four-hour on-cycles. Wire the interval timer to at least one bathroom exhaust fan. I recommend a 90 or 110 CFM fan with a 1 sone rating for a three-bedroom home.  Then install a 4-inch sheet-metal duct through the exterior basement wall to a closet, cupboard, or under a stairwell (to temper the cold air). If you want to get fancy, you can install a motorized damper on this pipe and inter-connect the motorized damper to the timer on the exhaust fan.  If you install a motorized damper, there is no need to run the duct to a closet.  When the fan comes on, the damper opens and outside air is pulled through the house to the exhaust fan. Or without the damper, the air is pulled in passively to the tempering zone (closet etc.) and throughout the house to the fan.

The third option also involves ducts, but these ducts are often small and easily retrofitted into existing buildings. Heat recovery ventilators (HRV’s) can be purchased in a wide range of sizes and prices. The amount and size of ducting varies significantly, depending on the size of the unit you choose and the sophistication of the system. Generally, the larger units are more effective. But any amount of air exchange will make a noticeable difference in your home. HRV’s are my first choice for the problems you have mentioned. But be careful in your selection. There are dozens of brands and sizes to choose from. Before selecting yours, do some research. If you select an “off the shelf” generic HRV start by calculating the cubic volume of air in your home (length x width x height of all rooms including basement area). Otherwise, seek the advice of a heating contractor. Their expertise often ensures that you get the best and most effective system for your particular situation.   

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This article was written by Steven Cannon, a Registered Building Official and partner in Lynch Building Inspection Services Ltd. of Nelson, British Columbia. It originally appeared in The Nelson Express.

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