Retrotec Residential Pressure & Air Leakage - Manual (Page 40)

Page 40 of 75
©Retrotec Inc. 2014
Measuring flue draft is another useful test to check the integrity of the venting system. Natural draft
combustion appliances with a negative pressure inside the vent can begin back drafting combustion products
back into the house.
To conduct a draft test
1. Drill a small hole in the vent pipe at the location identified in Figure 15.
2. Connect the red pressure tube to the “Ref A” (red) port on the gauge, and run it outside.
3. Connect the green pressure tube from the “Input B” (green) port on the gauge to the static pressure
probe (which is inserted into the drilled hole in the appliance vent).
4. The static pressure probe will cut down the effect of air flowing quickly past the tube, which can
have the same effect as wind on the pressure readings.
5. The “Ref B” (yellow) and “Input A” (blue) ports on the gauge must be open to the combustion room
pressure.
6. Press [Baseline] to start taking a baseline reading.
7. Wait for 60 seconds, or for the baseline measurement to be steady. Press [Enter] to apply the
baseline to the Channel A readings.
8. Turn the appliance ON, allow it to run for 5 minutes.
9. Set the gauge to measure pressure on Channel B (Mode “PrB”).
10. “PrA” is measuring the pressure from the outdoors to the CAZ, and “PrB” is measuring the draft
pressure.
Figure 15: Combustion appliance: Drill a small vent hole where indicated by the red star