Raypak AVIA 264 Quick Reference Manual page 27

Blower "Pre-Purge"
for 45 sec
Spark
Is Water Setpoint,
NO
Temperature and
"Heating" displayed?
YES
Unit Heating until
demand is satisfied.
Was Water
NO
Temperature
reached?
YES
Blower "Post-Purge"
for 3 minutes
Wait for new Heat
demand
END
Check for damaged or loose wires and terminals.
Diff Sw Closed
Check Blower and Air Pressure switch:
- Replace Pressure switch if failing open or close.
Diff Sw Open
- Replace Blower if operation is intermittent.
Fan Lockout
Ing Try Failure
Check Gas valve, Gas supply and spark igniter:
- Check gas supply and valve operation.
Ign 60 min Delay
- Check Igniter and wire. Replace if damaged.
Ignition Lockout
Check for damaged or loose wires and terminals.
Clock/Fireman Sw
Switch connected to safety loop is in OFF mode.
Water Sw Open Verify water flow / pressure. Clean Filter/Strainer.
Vent Sw Open Vent switch open. Troubleshoot extractor if installed.
Hi Limit 1 Fault Temperature Limit switch open. Verify water flow.
Hi Limit 2 Fault Inspect internal thermostat (Unitherm Governor) and
Cabinet Temp Lm bypass valve.
Air SW Open Air Pressure Switch failed in operation. Verify Blower
Diff Sw Fault operation. Check for air inlet/outlet obstructions. Verify
Fan Lockout air pressure.
Flame Lost Verify gas supply. Verify gas valve operation.
Flame Flickering Cut power, verify and clean igniter rods.
Flue Over Temp Verify obstructions. Troubleshoot extractor if installed.
Outlet Over Temp Verify water flow. Verify gas supply and combustion.
Low Flow Fault Verify water flow. Verify Pump operation. Adjust Flow
High Flow Fault as necessary. Verify filter pressure and clean if needed.
Control Logic - Flow Chart
27