Designers set CFM requirements for cooking lineups based on the type of equipment placed under the hood. Mechanical engineers take that data and design an exhaust system that connects to the hood or hoods to properly operate the system and meet NFPA 96 requirements for fire safety and operator comfort.

An HVAC contractor installs the exhaust system, connecting the duct(s) to the hood(s). Finally, a test and balance person tests out the system to verify that the newly installed system is meeting the air flow and volume requirements called for on the HVAC drawings. Usually, this T&B person is an employee of the installing HVAC firm. Furthermore, the T&B procedure is more often than not, done without any cooking equipment being turned on to provide the normal thermal plumes that exist during normal cooking processes.

On occasion a third party T&B contractor is hired to commission the system under operating load. The contractor should be TABB certified or equivalent. Commissioning provides the checks and balances to determine if the exhaust system is operating properly. A commissioning contractor also verifies that the specified equipment has been furnished and installed, and that the ducts are configured and sized properly. They may also be responsible for co-ordination all through the design process. But commissioning is another story that bears a full discussion at a later time.

It is suspected that a majority of hoods installed in commercial kitchens throughout the North American continent do not meet their design criteria. The reality is that none of us know when an exhaust system is under-performing unless we observe smoke escaping. Then we all look up and say the same thing, “the hood isn’t working”. Why? Because it is the only visible part of the exhaust system, so we all blame the hood.

New installations from Day One may not be operating properly. If there are no issues with smoke and capture, we totally forget about the energy impact. More often than not, the system may be operating well above or well below the design requirements.

Just like the exhaust system where we see only the hood, we are not aware of the energy load consumed and wasted electricity being used by a system operating at anything but design load.

Now, one company has introduced a system they call Halton Centurion. This system is described as the World’s 1 st Self Commissioning Hood System. It will be factory set to operate at the designers calculations and notify the operator when low or high pressure is affecting the system. It can recognize when filters are dirty causing high pressure and when a fan belt is slipping or broken causing low pressure.

It can be reprogrammed in the field when the cooking appliance lineup requires a change in the original calculations. Because it is so difficult to measure the flow and judge the effectiveness of an installed system, little to no follow-up is ever performed, only when and if a problem presents itself such as smoke escaping the hood.

The automated commissioning process involved with the Halton Centurion is comprised of several components. A calibrated pressure port sends a signal to a transducer which in turn sends a pressure signal to a controller. The controller adjusts the variable frequency drive until the desired factory pre-set setting is met. Commissioning is said to take only three minutes on a single hood system. At that point, the frequency drive maintains the setting as programmed.

For more information, use the following link for a clear explanation of the system. http://www.haltoncompany.com/news/centurion_web2.mht.