A.O. Smith TC-099 - Manual (Page 20)

AOS WPC - Tech Training 19 of 72 Ashland City, TN © 2007
Servicing should only be performed by a Qualified Service Agent
VF BOILER SERVICE MANUAL
START UP PROCEDURE (CONT)
Adjusting Manifold Gas
13. Set the boiler to Max Mode (Firing Modes - page 17). Check combustion readings using
combustion analyzer. Compare CO 2 readings taken to the high fire CO 2 table below. If
combustion readings are not in accordance with the high fire CO 2 table adjust as
follows:
Remove the flat, round, blue plastic cap from the top of the boiler’s 24 VAC gas valve.
Using a 3mm (7/64”) hex wrench, turn the high fire adjustment screw under the cap
counterclockwise to increase or clockwise to decrease gas flow and achieve the desired
CO
2 level per high fire table below. When desired adjustments are complete, reinstall
the cap on the gas valve. CO readings should be less than 200 ppm.
14. Set the boiler to Min Mode (Firing Modes - page 17). Check combustion readings using
combustion analyzer. Compare CO 2 readings taken to the low fire CO 2 table below. If
combustion readings are not in accordance with the low fire CO 2 table adjust as follows:
Remove the small metal slotted cap near the outlet of the boiler’s 24 VAC gas valve.
Using a TORX® T40 or a 5mm hex wrench, carefully turn the low fire adjustment screw
under the cap clockwise to increase or counterclockwise to decrease gas flow and
achieve the desired CO
2 level per low fire table below. When desired adjustments are
complete, reinstall the cap on the gas valve. CO readings should be less than 200 ppm.
Start Up Note: There will be a time delay between adjustments on the gas valve and the
response of the CO
2 measuring instrument. Adjust the settings in small increments and
allow the combustion readings to stabilize for at least 3 minutes before readjusting.
High Fire CO 2 Settings
Low Fire CO 2 Settings
15. When start up procedure is complete return to the User Settings Menu and place the
boiler back into Mod Mode firing mode (Firing Modes - page 17). Adjust the Operating
Set Point in the User Settings Menu (page 8) to desired system temperature. Remove
all test instruments and replace all plugs and caps.
16. Review page 67. The boiler must have a throttling valve on the outlet line. The boiler
should have a bypass line with a throttling valve. Adjust the outlet valve to achieve a 20
- 40°F temperature rise through the boiler and the bypass valve to achieve a 120°F
minimum inlet water temperature. Make these adjustments at 100% firing rate.
NATURAL GAS 8.5 - 9.0% CO 2
PROPANE GAS 9.5 - 10.5% CO 2
NATURAL GAS 6.5 - 7.5% CO 2
PROPANE GAS 7.5 - 8.5% CO 2