Hoyme Damper & HRV’s (Heat Recovery Ventilator)
More on cold air leaks in a house and the integrity of our building envelope to make our heating and cooling more efficient.
Many of our Canadian homes have at least one, more likely two 6 inch diameter holes in the wall letting cold air in when we don’t necessarily want it. There are other holes in our walls at all exhaust fans in the house which include bath fans, stove fans and laundry fans. We talk about a treatment for these exhaust vents at this link which describes Ultimate Vent’s treatment for these holes in our walls.
In Canada, if you have a gas fired furnace or hot water tank, the National Building Code will require that you have one 6 inch duct bringing outside air to the furnace room for combustion air for the gas to burn.
Typically this is an insulated duct that drops onto what is referred to as a bucket which sits on the floor of your furnace room. If you have ever been in the furnace room when it is 20 degrees below outside, you have felt how cold this air is and it continually siphons into the house. The bucket mitigates the siphoning action a bit but for all intents and purposes you have a 6” hole to the outside pouring in cold air.
Well an Alberta inventor named Cliff Hoyme has invented a motorized damper that controls this air flow. Since 1984 Hoyme Manufacturing has been producing motorized dampers for the HVAC (Heating and Ventilation) industry. The dampers open to let air in when called for by the gas fired appliance.
For more information please go to their website at: http://www.hoyme.com/
The second 6 inch hole in most houses, particularly if they have a forced air heat distribution system, is the make up air duct going to the furnace plenum to make up for any air lost out of the house when the furnace system is on. This is called the make up air and places where this air might be lost would be places like stove and bathroom fan vents, around windows, doors opening and closing, around windows, and others.
One use of HRV systems is to preheat this air coming into the house by an air to air heat exchanger. You can imagine 20 degree below zero air needing to be heated to 20 degrees or normal room temperature. Preheating this air makes for a more efficient use of your heating system.
The HRV is set up to capture the heat from exhausting stale air from the house while transferring that heat to fresh air entering the house. Some sources suggest that 70-80% of the heat is captured from the exhausted air.
Another use of HRV systems is to improve air quality in our modern air tight homes. These are stand alone systems that do the same heat exchange we outline above but has its own network of ducting to collect stale air and to distribute fresh air. These are typically a smaller diameter duct work than a furnace system.
For more information go to this link