Urgent Safety Notice For Air House Testing

Post Air House Testing-01

Note: CEC’s Combustion Safety Team has observed unsafe practices while observing tradesmen doing Air Heater Safety Checks

In some cases, cracks or voids may exist in the heat exchanger surfaces. This can cause the combustion chamber to become pressurized by the supply air fan. This condition can cause the flame front to escape the combustion chamber through any portholes or openings. For this reason the following safety guidelines must be strictly adhered to.


Prior to Startup:

  • Verify that the viewing porthole inside the vestibule is in place and secure.
  • Verify that the main relief hatch/viewport or the outside of the unit is free moving and not stuck in a closed position.
  • Verify that no other workers are working in the area around the relief hatch.
  • Check that the balance damper for the induction fan in NOT closed and that it is locked in it’s open setting. Typically these dampers may have been set at a position less than full open when the flame was balanced. Over the years, the locking mechanism may have loosened which can allow the damper to swing full closed.



If a low combustion air problem occurs a back draft condition may be present. This condition can cause the flame front to flash out through openings seeking oxygen to burn.

  1. Step Outside: After initiating the air house startup step outside of the vestibule. Wait outside until the unit goes into high fire and observe that no problems occur before reentering the vestibule.
  2. Relief Hatch: When observing the flame through the main relief hatch/view port on the outside of the unit, hold the hatch closed with a tool or before putting your face near. Always wear eye protection!


Honeywell Combustion Safety has been in business since 1984. With engineers and staff members that sit on Code committees such as NFPA 56, NFPA 85, NFPA 86, and NFPA 87, our inside expertise is integrated within all of our practices and our global reach ensures that customers around the world are kept safe. Honeywell Combustion Safety offers Testing and Inspections, Engineering & Upgrades/Retrofits, Gas Hazards Management, Training, and Field Services for all industrial facilities and different types of fuel fired equipment. Contact Honeywell Combustion Safety at +1 216.749.2992 or visit www.combustionsafety.com for additional information.


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