Start Up Procedure - A.O. Smith VF VB 1000 Service Handbook

START UP PROCEDURE

Prior To Start Up
In addition to normal supplies and hand tools necessary for installing and servicing water
heaters and boilers the following tools and test equipment should be on hand. See the tool
requirements page 3.
• A combustion analyzer capable of measuring draft pressure, CO, and CO
• True RMS Digital Multi Meter DMM capable of reading AC volts, DC volts, ohms,
DC micro amps µA, and frequency Hz.
• AC amp meter.
• TORX® T40 or 5mm hex wrench - for setting gas mixture at gas valve.
• 3mm or 7/64in hex (allen) wrench - for setting gas mixture at gas valve.
• A U-tube manometer or pressure gauge for measuring supply gas pressure.
• A digital manometer for measuring (negative/vacuum) manifold gas pressure.
Firing Modes - Min/Max/Mod
When performing a Start Up on a VF boiler, the boiler's firing mode must be set to the Min
Mode (minimum firing - 25%) and the Max Mode (maximum firing - 100%). While the boiler
is firing press the Menu button on the UIM (page 7). Using the Up and Down buttons scroll
down until the > cursor to the left of the display is lined up with the User Settings menu and
press the Select button. Scroll down to Mod Mode menu item and press the Select button
again. The > cursor starts flashing on and off slowly indicating adjustment of this menu item
is now possible. Use the up and down buttons to select between these three options:
• Min (forced minimum firing rate - 25%)
• Max (forced maximum firing rate - 100%)
• Mod (MCB automatic controlled firing rate - modulation mode)
Press the Select button for the desired option to confirm. The > cursor stops flashing and the
boiler enters the firing mode selected.
The Min Mode and Max Mode are used for checking combustion during start up. Return the
boiler to the Mod Mode after checking combustion. The boiler will automatically return to the
Mod Mode after 10 minutes. Review the UIM and Menus information on pages 4 - 10.
Turning The Boiler Off
NEVER TURN THE BOILER OFF BY SECURING POWER WHILE IT IS FIRING. Repeated
sudden stops while firing can damage the boiler. To shut down the boiler safely do one of the
following so the boiler can go through a normal shut down sequence with post purge cycles:
• Lower the Operating Set Point to it's lowest setting.
• Lower the set point of any external control in use to it's lowest setting.
• Open the boiler's 24 VAC Enable/Disable circuit manually (wires in the junction box on the
back of the boiler). Be careful not to let the bare wire ends touch any grounded surface.
AOS WPC - Tech Training
VF BOILER SERVICE MANUAL
Servicing should only be performed by a Qualified Service Agent
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