Thermo Products OPB (24, 36)- 80, 30 service manual

All installations and services must be performed by qualified service personnel.

NOTICE: To achieve proper combustion and the efficiencies listed in sales brochures, instruments must be used to secure CO2 or O2 readings.

ii.CARBON DIOXIDE (CO2) OR OXYGEN (O2): Take a CO2 sample from flue passageway. It is possible to achieve readings of up to 14% CO2 (or 2% O2 ), but it is better to have a slightly lower CO2 (or higher O2) reading with zero smoke measured. To achieve a lower CO2 reading, open the air band, or shutter, on the burner until zero smoke is measured.

For example, if a 13% CO2 (or 3.5% O2) is recorded at a trace of smoke, open the air shutter until zero smoke is measured with a 12% CO2 (or 4.5% O2).

Adjustment of the burner to achieve a slightly lower CO2 reading is recommended, although it slightly reduces combustion efficiency, to keep the heating system within normal operating conditions though external conditions may vary. Some “out-of-spec” conditions which may adversely affect burner performance are, low oil supply temperature, dirty (contaminated) oil, low heating content (BTU/gal) oil, cold heat exchanger surfaces, and downdraft conditions. By adjusting the burner in this manner, an operational tolerance is established allowing the burner to function well, even under less than ideal conditions. This results in less service and maintenance during a heating season.

iii.FLUE GAS TEMPERATURE: The flue gas temperature will vary to some extent depending on the heat input rate, duct design, and the amount of air flow across the heat exchanger. The suggested minimum net flue gas temperature is 3500 F, and the maximum gross flue gas temperature is 5500 F. The lower the flue gas temperature, the higher the heating efficiency. However, stack temperatures under 3500 F may result in condensation of water vapor in the flue gases, which in turn promotes corrosion of the heat exchanger.

iv.TEMPERATURE RISE: Temperature rise is equal to the supply air temperature minus return air temperature. Under steady state operating conditions, the temperature rise across the heating section should be approximately 650F. A higher temperature rise will slightly lower the heating efficiency. A lower temperature rise will slightly raise efficiency, but may cause condensation.

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