Commissioning is the process through which the new furnace system is verified and adjusted so that it performs per the manufacturer's and owner's requirements. Beyond visual inspection of components such as the filter media, a series of tests should be completed with the help of instrumentation (manometers, thermometers). The results of the testing are then compared against acceptable values (often manufacturer specified) in order to calibrate the new furnace and the information is recorded on a commissioning checklist (to be provided to the homeowner). Specific guidance on the procedures and equipment needed for commissioning is provided in TECA and HRAI documentation (See Additional Resources section).

A simplified commissioning process for the new furnace will include at least the following:

• Inspection of individual system components including filters, wiring, and gas lines.
• Complete a pressure check of the supply gas line "up stream" and manifold gas pressure "down stream" of the appliance gas valve. Adjust "down stream" manifold pressure as needed to meet the furnace manufacturer's nameplate value.
• Check the firing rate of the furnace by "clocking-the-meter". The high-firing rate of the furnace must not be outside 10% of the rated BTU/hour input. Alternatively, the manifold orifice size can be determined in order to confirm the furnace rated BTU/hour input. In this case , the size of the orifice is visually determined by the drill size of the hole and the manifold pressure is then measured with a manometer. Together this information is used to determine the amount of gas that will flow into the burner.
• Calculate the furnace temperature rise by measuring the air temperature of the supply and return air, respectively. Confirm that the temperature rise lies within the manufacturer's stated tolerance. For example, on a two-stage gas valve furnace, the temperature rise should be taken at both high-fire and low-fire.
• Complete an external static pressure test (ESP) and confirm that the tested value is aligned with TECA or HRAI recommendations. Complete ductwork modifications as necessary. Refer to page 20 under solutions for both low and high ESP.
• Document all testing information on a commissioning checklist and record any outstanding issues for follow up with the homeowner.