•Disengage water valve from reversing valve and remove from boiler. see diagram 32.

REPLACEMENT OF PARTS

•Remove clip holding pipe to heat exchanger inrear of water valve. From front of boiler, grip clip with long nosed pliers and pull upwards. •Unscrew and remove large screw holding water valve to back plate of reversing valve assembly,
Diagram 35 Des 058 Note: All boilers are tested and factory set duringmanufacture. Should it be necessary to reset a gas valve, for example after replacement, refer to 'Set-tings'. Note: Use new 'O' ring provided between gas valveand burner supply pipe. •Refit electrical connections to replacement gas valve as follows:-BLACK leads to modulating coil. -WHITE leads to EV1 and EV2 terminals of mainsolenoid-RED lead to COM terminal of main solenoid. To replace modulating coil
Diagram 36 •Ensure gas supply is off. •Disconnect two black electrical leads from gas valve modulating coil. •Unscrew and remove two screws holding modu- lating coil to gas valve and remove coil from gas valve. •Fit replacement modulating coil in recerse order to removal. •Reconnect electrical leads to replacement coil.
Mec 117 •Disconnect two white and one red lead from gas valve main solenoid. •Pull off clear plastic tube from gas valve to sealed chamber tapping point. •Unscrew main gas supply pipe nut on top of gasvalve, releasing spark ignition unit bracket, •From below boiler, unscrew gas valve connec- tion between gas valve and fixing jig isolating cock. •Unscrew and remove two screws securing gas valve to bottom plate of boiler. •Remove gas valve from boiler. •Refit replacement gas valve in reverse order to removal. see dia-gram 36. 22