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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 CO2 measuring instrument. Adjust the settings in small increments and allow the combustion readings to stabilize for at least 3 minutes before readjusting. High Fire CO2 Settings NATURAL GAS 8.5 - 9.0% CO2 PROPANE GAS 9.5 - 10.5% CO2 Low Fire CO2 Settings NATURAL GAS 6.5 - 7.5% CO2 PROPANE GAS 7.5 - 8.5% CO2 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. 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 POOR COMBUSTION - IGNITION PROBLEMS If the high and/or low fire CO2 combustion readings are not in accordance with the tables shown on page 19, the CO readings are high, or if the boiler is experiencing ignition failure or rough starting perform the following procedures: Adequate Combustion - Proper Venting 1. Ensure there is an adequate supply of fresh air for combustion and the boiler is vented properly. DO NOT OVERLOOK THIS STEP. Lack of combustion air and improper venting is often the root cause for poor combustion. Direct Vent Installations: If the boiler is direct vented ensure the intake air or the vent pipe is not restricted and neither has exceeded the maximum 70 equivalent feet. Ensure the vent and intake air terminations are positioned correctly so that vent gases are not recirculating to the intake air termination. Installation note: each 90° elbow is equivalent to 10 linear feet of pipe on VF boilers. If the boiler is in an equipment room with a door to the outdoors, temporarily disconnect the intake air pipe and prop open the equipment room door. Take combustion readings again to see if this corrects the problem. Conventional Vent Installations: If the boiler is using room air for combustion ensure the vent pipe has not exceeded the 100’ maximum equivalent feet. Installation note: each 90° elbow is equivalent to 10 linear feet of pipe on VF boilers. Ensure the fresh air openings in the equipment room are adequately sized for the combined input Btu/hr rating of all conventionally vented gas fired appliances in the room. If the boiler is in an equipment room with a door to the outdoors - prop open the equipment room door. Take combustion readings again to see if this corrects the problem. General venting guidelines are shown here. Refer to the Instruction Manual that came with the boiler for complete combustion air and vent installation information. Direct Vent Configurations Installation Note: VF Boilers are classified as Category IV appliances. AL29-4C vent material must be used for the exhaust vent on all installations. Conventional Vent Configurations AOS WPC - Tech Training 20 of 72 Ashland City, TN © 2007 Servicing should only be performed by a Qualified Service Agent VF BOILER SERVICE MANUAL POOR COMBUSTION - IGNITION PROBLEMS (CONT) Burner Inspection 2. Remove the burner and inspect the burner for any signs of damage or debris inside. If the burner is damaged or contaminated with debris - replace the burner. Check all gaskets in the burner/blower assembly for wear or damage. Replace any worn or damaged gaskets. Firing Rate - Modulation Performance 3. The firing rate on VF boilers is modulated or controlled by blower speed (see pages 11 through 14). Ensure the correct Config Key (page 14) is installed for the input Btu/hr rating and fuel type of the boiler you are working on. 4. Verify the blower speed is acceptable during the following three operating states: • Igniter warm up period - (AC amps can be detected through the igniter). • Min Mode (Firing Modes - page 17). • Max Mode (Firing Modes - page 17). Start the boiler and check the three parameters listed below during the three operating states given above. • DC voltage sent by the MCB at the VFD (page 11). • Actual blower rpm as sensed by the Hall Effect sensor (page 13). • Actual power frequency (Hz) on the VFD display (page 11). Procedure • Measure the DC volt instruction from the MCB at the VFD to ensure all wiring and connections between the J24 socket on the MCB Daughter Board and the VFD are intact (page 11). • Check the actual blower rpm from the Control States Menu via the UIM display (page 13), • Check the displayed Hz on the...

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