Test Products International 709 - Manual (Page 34)

Notes: Appendix I: Technical Notes
Note 1: When performing a pressure or draft test during a combustion test, the
pump can be turned on to provide a continuous sample to the sensors. This
enables pressure adjustments to be made and the affect to the combustion
process can be seen by returning to combustion analyzer mode. Use the FUNC
Key to activate manometer mode. Press and hold the Up Arrow Key until the
pump reactivates. Perform a pressure test and then use the FUNC key to activate
combustion analyzer mode. Repeat this process until pressure adjustments are
complete.
Note 2: Several factors affect combustion efficiency. Dirty or clogged air filters
reduce the amount of air available for combustion therefore reducing efficiency.
Obstructions in the flue block exhaust gases and alter the air mixture in the com-
bustion chamber which reduces efficiency. Air leaks in the combustion chamber
also alter the mixture causing decreased efficiency.
Note 3: The primary way to affect change in combustion efficiency when working
with modern gas fired equipment is through gas manifold pressure adjustment.
Confirm manifold pressures are within maufacturers specifications prior to per-
forming a combustion test. Once manifold pressures are within limits a combus-
tion test can be performed to provide information regarding any adjustments that
may be needed.