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Retrotec Manometer Setup

In order of how I do a home energy audit.

Preparing the house

  • Close all exterior doors, windows and attic hatches
  • Close fireplace dampener and cover ash with damp newspaper and tarp or seal off the fireplace with tape
  • Open all interior doors
  • Shut off the AHU, dryer and exhaust fans
  • Put water heater on pilot to prevent back-drafts while running

Setting the baseline

A baseline is done to find how the house is operating as you found it and to normalize any wind of outside influences

Input A: hose inside WRT outside (Ref A).  All fans and air handler are off and all external doors and windows are closed.

  • Press : “Baseline”
  • Press: “Start”
  • Wait 10-15 sec for reading to stabilize and press “Enter”

Initial tests:

Provide information on how the home is operating now and how the operation may change due to work completed.  Need to document conditions as found, info on potential measures and info on the impact of measures.  Post air sealing tests must be done if any building envelopment changes were made.  Post pressure balancing test find how the house is operating after it has been pressure balanced.   

Dominant duct leakage

Tells us if there is more duct leakage on the supply or return side 

Input A: hose inside WRT outside (Ref A).  All air handlers are on.  Record + or – Pascal reading.

  • Dominant with air handler on 
  • Baseline with air handler off
  • Negative pressure means more leakage on the SUPPLY side
  • Positive pressure means more leakage on the RETURN side (PR is how I remember)
  • Take one dominate duct reading for each zone or HVAC system

Room pressures

Tell us the pressure created in the house by the AHU (when the doors are closed)


Causes of dust, allergens, loud system, and comfort issues.

Input A: Input to room with door to room shut and AHU ON WRT outside (Ref A).  Record pressure created in room.  Test each room that has a vent and a door. 

  • Room pressures with air handler on 
  • +/- 3 is threshold (want no larger than +3 or no more negative than -3)
  • If room pressure exceeds BPI threshold, recommendations for pressure relief need to be made
  • Put hose under closed door
  • All interior doors are open except the room you are checking (is closed)
  • Always go clockwise around the house and begin with the first door from the blower door

Blower door test

PrA: Input open to house, reference to outside (Ref A) and establish 50 Pascal’s difference.

Ref B: Input to fan tap (yellow tap), reference to inside, record fan pressure in Pascal’s and whole house CFM 50.

  • 50 Pa are required (top reading)
  • More rings reduce fan opening à creating more pressure
  • Use Range Config button for switching configuration of the fan (Open, A, B C rings etc)
  • This is the only test that deals with CFM
  • Use Mode button to switch to CFM

Pressure pans

Provides info on duct leakage

Input A: Measure leakage at each supply and return register in Pascal’s with hose input WRT inside of house.  Measure registers clockwise within the house and the rooms.

  • Anything over 1 Pa is a leak.  Anything under 1 Pa is relatively leak free.
  • 50 Pa is the highest number you should ever get and that means the duct line is completely open to the outside (or disconnected).
  • If get a number greater than 50 Pa, then the AHU is probably on or you are stepping on the tube.
  • We have the blower door set at 50 Pa so it is impossible to get anything higher.

Zone pressures

Provides information on the pressure boundaries of the house

Input A: Insert probe with hose into zone WRT interior of house to determine if the zone is connected more to the outside or inside.  The pressure boundary of the home is made up of the surfaces that are designed to control air flow (we want to keep inside air in and outside air out).

  • 0-10 Pa indicates zone is inside envelope
  • 11-39 Pa is "confused"
  • 40-50 Pa indicates zone is outside envelope
  • Insulation is a thermal boundary
  • Pressure boundary is hopefully the Sheetrock.
  • House is at -50 Pa WRT outside

CAZ test

Provides information on the pressure created by fans in zone containing a combustion appliance

Input A: Input in zone where combustion appliance is located WRT outside and measure in worst case first (doors shut and all fans and AHU on).  

  • CAZ is done with house under worst case conditions (all the fans running)
  • With one exception – if dominate duct leakage is positive then turn the AHU off
  • You want the most negative number you can get for CAZ (-100 is better than -1 for CAZ)
  • Watch out for the potential of back drafting combustion appliances

A home fails the CAZ test if there is a CAZ pressure greater than -3 Pa

Recommendation options
  • Make changes that will reduce the negative pressure
  • Inform the client, in writing, of the problem and explain what is causing it
  • Home with attached garages must get a CO alarm in the house
  • Need to test the CAZ of the house WRT the garage
  • CAZ work is done before any sealing is done, after house pressures are neutralized

Draft test

Draft test tells us the pressure difference between the two ends of the flue

Input A: With the water heater / atmospheric furnace turned on, measure the flue draft with the hose connected to the draft probe and record draft after appliance is fired up within the first minute of operation.  

Drill your hole between 12-inches and 24-inches from the top of the diverter on naturally vented appliances

BPI standards

  • < 10 degree F outside requires -2.5 Pa or more negative
  • 10 – 90 degrees F outside requires formula (T/40) – 2.75 Pa or more negative
  • > 90 degrees F requires -0.5 Pa or more negative

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