This is one item that most tenants or owners of apartments or condominiums know nothing about in their daily travels in and out of the underground garage. There are sensors or more specifically sniffers mounted on the columns of the garage at about 50” above the floor and spaced approximately 50 to 75 feet apart that are checking for the fumes from automobile exhausts that are toxic. The detection system will initiate the garage exhaust fans when a specific concentration of CO (carbon monoxide) is reached or sensed and then cycle the fans off when the levels are back to normal. Prior to the monitoring systems being installed the garage exhaust fans would operate 24 hours a day or possibly on deluxe systems cycle off with a time clock between 11:00 PM and 6:00 AM. This was a tremendous waste of electricity, but more importantly, the noise that the fans made was so loud that if someone were to be in distress and scream for help they would not be heard. The exhaust fans would average between 36” and 48” in diameter and there would be as many as 2 or 3 per level in the garage, exhausting into a large concrete shaft that terminated above ground, outside the building. There would be fresh air intake louvers on the opposite side of the garage that allowed fresh air to enter, replacing the exhaust air. The cost of the new CO system was realized in energy savings in a few short years. For maintenance of the sensors, it is important to keep them clean and testing can be accomplished with a small aerosol can of compressed carbon monoxide and a squirt into a small plastic bag held around the sensor. Your HVAC contractor can test the operation of the monitoring system during routine maintenance of the exhaust system. The latest systems on the market are wireless that reduces the installation costs tremendously, but requires battery replacement about once a year. There is really only one supplier of these systems now and that is Honeywell since they bought out the company, “Vulcain” that was the leader in monitors for CO and all other gases.

As a side note to property managers it can be part of the HVAC contractor or Electrical contractor’s specification to install the monitoring system for noxious gases, but most likely be part of the HVAC service and maintenance contract to perform regular testing and maintenance. Be aware that CO (carbon monoxide) is produced during incomplete combustion of a fuel whereas CO2 (carbon dioxide) is produced during complete combustion of a fuel. Both CO and CO2 are deadly toxic to oxygen breathing life forms and the parts per million need not be very high to feel the effects that start as headaches and nausea followed by eternal sleep.

Testing the operation of a CO system is different from calibrating. Testing ensures the exhaust fans start and the fresh air dampers open when the sensors detect CO or CO2. Calibrating the system ensures the sensor initiate the exhaust system at the proper concentrations of gas levels so no one gets sick or dies. Your HVAC contractor can test the operation with purchased aerosol cans of CO / CO2 and verify that the fans and fresh air dampers operate. I have recently found out that the Ontario Building Code requires all noxious monitoring systems in garages to be “Calibrated” twice per year regardless of how many times the system is “Tested”. It is simple enough to see the system operate, but if it does not start until the PPM (parts per million) are way over the limit, someone could die. As an HVAC contractor I can purchase the meters for calibrating the system. The meters themselves require regular calibrating and certification just in case something goes wrong and even then there could still be liability and risk of an insurance claim. As a contractor or you as a property manager, I would have to ask if it is worth the risk to have anyone other than the manufacture perform the bi-yearly calibration. As an HVAC contractor I have no fears of the Honeywell Analytics Division taking my account as they only service the CO monitor and sensors, no the exhaust fans, intakes or any other mechanical devices under our contract. This is the same reason your HVAC contractor does not service and maintain your elevators.

Please be advised that no vehicles using LPG (liquid petroleum gas) (propane) can park in underground garages. This also applies to storage of propane cylinders for camping or trailers in the underground garage or storage lockers.