To ensure accurate blower test results—and to avoid gas leaks, fire, and other hazards—it helps to follow a checklist while making a walk-through of all floors of the house, including the basement.
• Turn off all thermostats. This ensures that the HVAC system doesn’t affect the air flow measurements. If the house has more than one thermostat, make sure to turn them all to “off.”
• Seal the attic access. In most cases, taping the perimeter of the access panel will temporarily stop any air leaks long enough to perform the test.
• Close all windows and exterior doors. Even a slightly open window will affect test results. Window jambs and seals are often the source of leaks, which show up clearly when the windows are shut tight.
• Leave interior doors open. This promotes the free flow of air throughout the house.
• Turn off gas kitchen appliances. Make sure pilot lights are off and inform clients that no cooking can occur during the test.
• Turn off exhaust fans. This includes the range hood and all bath fans. Also make sure the clothes dryer is off.
• Turn off gas heating appliances. Turn off both the furnace and the hot water heater. Otherwise, a change in pressure could extinguish the pilot and cause a gas leak.
• Close fireplace and wood-stove dampers. Any wood fires must be completely out (no coals or embers) before you run the test. This usually means asking the homeowners to extinguish or let a wood fire burn out before you even arrive at the house.
And here’s an important “business survival” tip from Ray Williams, a superintendent with Mark IV Builders: Whenever he shuts off a furnace or water heater, he places his car keys on top of the appliance. That ensures that after the test, he never leaves the house without going back to turn all of the gas appliances back on. That prevents phone calls from angry clients who have no heat or hot water.