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This research project was performed to gather field experience with houses that had ventilation systems that were expected to be able to meet the CSA F326 Residential Mechanical Ventilation Systems Standard.
The study focused on houses that had central forced warm air heating systems along with central ventilation systems. Two of the houses had air to air heat exchangers, and two had central exhaust fans. The four houses were built between 1983 and 1986.
A total of four houses located in Saskatoon were measured for the following quantities: ventilation rates, room air flows, duct leakage, sound levels, fan energy consumption rates and house depressurization levels caused by the operation of the ventilation system.
Three of the four houses had ventilation systems that were found to meet a 0.3 air changes/hour capacity. The fourth house had a measured air change rate of 0.22 ac/h. However, only one of the four houses could meet the minimum ventilation requirement of the CSA F326 standard based on individual room supply requirements. The minimum ventilation supply requirement for the houses varied between 55 and 70 L/s. None of the houses were able to meet the 30 L/s exhaust air flow requirement for the kitchens, and only two of the houses were able to meet the 10 L/s requirement for each of the bathrooms. Using a strict interpretation of the F326 standard, all of the houses would fail the minimum ventilation requirements.
Two of the four houses could meet the ASHRAE Recommended Noise Criterion of NC-30 or less.
In one house, the central exhaust fan had been running for seven years with no maintenance or cleaning (there was no filter on the fan). Approximately 6 mm of dust had accumulated on the fan rotor. After cleaning the fan, the air change rate was found to increase from 39 to 63 L/s, and the noise level of the fan was found to drop from 40.7 to 37 dBA.
Significant air leakage was found to exist in the ductwork in both the warm air distribution system and in the exhaust air system in a number of the houses. One house was found to have 91% leakage in the warm air distribution system (only 9% of the air entered the warm air return grilles, the remainder of the air entered through duct leakage.)