Outline of Blower Door Test.

Here is a step-by-step outline of all the elements of a good
residential blower door test. It will help you avoid all the
most common mistakes.

INFORM THE HOUSE OCCUPANTS & OWNERS ABOUT THE TEST BY LETTER OR PHONE:
- Air leakage is about 1/3 of heat loss of house and it is uncomfortable.
- Blower door test will find what kind of leaks your house has.
- The test will be like a 20 mph wind on all sides of the house.
- A large fan is sealed into an outside door and air is blown out of the house.
- Leaks can be detected with by feeling with the hand or with a smoke puffer.
- The test is not dangerous and everyone can remain in the house during the test.
- The test will help to determine if how much leak sealing is reasonable.
- The furnace MUST be shut off during test.
- The blower door test is unlikely to damage house, but may change the temperature.
- The test MUST NOT be done with fires in fireplaces, furnaces or stoves.
- Ashes in fireplaces MUST BE REMOVED OR COVERED and dampers closed to avoid ashes in house.
- Ask occupants where they think the worst drafts are.
- Close and seal outside doors and windows as if winter (any storm windows on).
- We will need to go in all rooms, attic & basement to look for leaks.
ARRIVE AT SITE - EXPLAIN TEST AND PREPARE THE HOUSE:
- Greet occupant and reconfirm permission to do the test.
- Go over everything in the introductory information.
- Check to see if they are comfortable with idea of test and answer all questions.
- Inspect house preparation:
  - Are there any fireplaces or stoves for heating?
  - Are all fires out in stove and fireplaces?
  - Have ashes been removed and are dampers closed?
  - If ashes not removed, cover with newspapers & weight
  - Have all doors and windows been closed & latched with storms on?
  - Are all interior doors open, except closets?
  - Is the basement heated (lived in) an to be included with envelope?
  - Adjust thermostat to keep furnace off even it temperature drops.
- Ask homeowner for their ideas where the worst/uncomfortable leaks are.
- Bring in blower door gauges and set them up so they can warm up before the test.
DEFINE THE HOUSE THERMAL ENVELOPE
- Ask yourself, "What parts of house are heated above 45F?"
- Is the basement is part of the thermal envelope? Open the basement door if it is.
- The walls, ceilings, and floors that enclose the heated volume are the thermal envelope.
- Measure the outside dimensions of the and compute house volume (cu ft).
- Optional: Compute surface area of walls, floors and ceilings (sq ft).
SET UP BLOWER DOOR
- Install the Door Frame in a house door jamb.
  - Select door on the side of house shielded from wind.
  - Assemble the blower door frame with the cams closed.
  - Expand the door frame to roughly fit the door jamb and tighten knobs.
  - Remove the door frame and attach the nylon cover.
  - Connect exterior house pressure hose to the outside of the nylon door panel.
  - Run the exterior house pressure hose away from the fan flow direction.
  - Install the door frame in the door jamb and open the cams to lock it into the jamb.
  - Check for leaks and reinstall if necessary.
- Install fan in the depressurization direction (fan blowing out).
  - Insert the fan into the elastic seal around the door cover hole.
  - Check for leaks and adjust the fan seal (if necessary).
- Set up the gauges on the door jamb.
  - Attach the gauge clamp to the door jamb at viewing height.
  - Attach the gauges to the gauge clamp.
- Connect the pressure tubing to the gauges and outside.
  - Connect the fan pressure hose between the fan and gauges.
  - Connect interior house pressure hose between the nylon door panel and the house pressure gauge.
  - Make sure that exterior house pressure hose is not exposed to the fan flow.
- Connect the electrical plugs.
  - Connect the fan speed control plug to the female plug to the fan.
  - Turn off the fan speed control switch.
  - Connect the male fan plug to an extension cord connected to a wall AC power outlet.
- Carefully zero the pressure gauges.
  - Turn on the fan and run up the power several times so that the gauges move.
  - Adjust the gauges to zero.
  - Tap the gauges gently to make them come to zero.
  - Repeat the last three steps until the gauges come to a consistent zero.
RECORD WEATHER CONDITIONS
- Record inside temperature (within 5 degrees F) for use in air density calculations.
- Record outside temperature (within 5 degrees F) for use in air density calculations.
- Record wind conditions (calm, gusty, very windy, etc.) for use in evaluating measurement quality
MEASURE AIR FLOW AND PRESSURE
- Adjust the fan speed for a house pressure of 50 Pascals (this is the same as 0.20 inches of water).
- If you can not get up to 50 Pa, use highest pressure you can reach.
- Check for open windows and doors that have come open.
- If the flow gauge reading is too low to read, install the Low-flow plate.
- If using the low-flow plate, move fan pressure hose to low-flow plate pressure tap.
- Record pressure and flow.
- When the fan is running slowly, use the low speed switch for more sensitivity and fan cooling.
ANALYZE DATA
- There are several ways to analyze data and here is a simple one:
- Calculate house volume in cubic feet (example: 1500 sq ft * 8 ft = 12000 cu ft)
- Inside and outside temperature can be used to correct data with computer.
- Use 50 Pa pressure and flow data (example: 50 Pa and 2000 cfm)
- Compute 50 Pa Air Changes/Hour (ACH50)
- Example: ACH50 = 2000 cfm * 60 min/hr /12000 cu ft = 10 ACH50)
- Use "can't reach" table if house is too leaky to get to 50 Pa
- Compute natural infiltration by dividing ACH50 by 20 (approximate)
- Example: 10 ACH50 / 20 = 0.5 ACH natural infiltration
- Minimum Infiltration: ASHRAE recommends a minimum Infiltration = .35 ACH
- This suggests a minimum ACH50 = 20 * .35 = 7 ACH50
- Houses that are leakier than 7 ACH50 should generally be airsealed.
SEARCH FOR LEAKS
- Check each room for major leakage by partially closing each interior door and feeling for air flow through the door crack.
- Use our hand or a smoke puffer to find individual leaks.
- Remember that leaks in the upper part of the house cause the worst heat loss.
TAKE DOWN THE BLOWER DOOR
- Turn off the Fan Speed Control.
- Disconnect the two Electrical Plugs.
- Disconnect the two pressure hoses.
- Remove the fan from door.
- Release door frame cams.
- Remove the door frame from the door jamb.
- Disconnect door frame and store in case.
- Remove the gauges and gauge clamp from the door jamb.
FINISH TEST AND RESTORE HOUSE TO ORIGINAL CONDITION
- Turn on thermostat/furnace and warm up house if necessary.
- Return all doors and windows to original setting.
- Pack up all blower door equipment and return to truck.
- Remove any covers from fireplace or stove ashes.
- Thank occupants for their cooperation.

For further assistance, call (540) 943-2776 weekdays 7AM-4PM ET.
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