UNIT SERVICE
HCV & HCVR Evaporative Cooling & Gas Heating
Page 21 of 26
Heating Section
Unit locks out
(red fault light comes on) –
1.
Press reset button. If unit does not start refer sections below.
Pilot flame lights but will not hold in
1.
Pilot flame too small or yellow. – Clean pilot line, primary air opening and orifice. Adjust flame
and/or flame rod position to ensure pilot flame wraps completely around the flame rod.
2.
Flame rod shorting out. – Check flame rod lead and replace if deteriorated. Check electrode
porcelain for cracks and leakage to earth – replace where necessary. If problem persists after
carrying out above instructions, it is probable that the electronic program control is faulty and will
require replacement.
Heating not delivering proper amount of heat
1.
Undersized orifices or gas pressure too low. Check with gas supplier or manufacturer before
changing injectors or adjusting regulator. Be sure that gas pipe sizing is adequate.
2.
Low air delivery. Clogged filter pads. – Replace or hose out. Check fan speed. Clean blower blades.
3.
Dirty flue tubes. See cleaning instructions.
4.
Discharge dampers not closing. Check for loose linkages. If damper motor is faulty – replace.
Flame flash back and burning at orifices.
1.
Gas input too low at full fire. Increase gas pressure (by regulator adjustment if possible)
2.
Defective burner ribbon. Replace
3.
Excessive primary air. Adjust primary air shutter for correct primary air.
4.
Low fire rate set too low. Adjust bypass rate screw (high/low Manufactured gas unit); or modusnap
bypass screw requires adjustment (Natural and LPG units)
Delayed or rough ignition
1.
Dirt in main burner orifices. Remove and clean.
2.
Burners covered with scale or other foreign matter. Remove and clean
Pilot flame goes out
1.
Flame too small – Clean and adjust – refer to cleaning burners section 3.
2.
Dirt in pilot line or orifice – See cleaning instructions.
3.
Gas pressure fluctuates wildly – Check operation or pilot regulator. Replace if necessary.
4.
Low gas pressure at unit – Increase line pressure or line size.
5.
Pilot flame ‘Lifts’ – Adjust pilot gas regulator.
6.
Check flame sensor rod on pilot assembly is not earthed out on heat exchanger.
Pilot flame does not light
1.
No ignition spark – Loose or disconnected high tension lead. Rectify. Faulty flame control –
Replace.
2.
No gas at pilot burner – Faulty pilot solenoid valve – Replace. Loose wire to pilot solenoid valve –
rectify. Blocked pilot orifice – clean.
3.
Check that ignition cable isn’t braking down to earth before electrode.
4.
Check pilot injector isn’t blocked in pilot assembly on burner bar.
Burners do not come on when pilot flame is alight and room thermostat is ‘Made’.
1.
Loose electrical connection or gas valve not in circuit. – See wiring diagram – check for electrical
supply at valve terminals and in junction box.
2.
Limit switch defective or stuck in open position. – Bridge across limit switch terminals. If burners
light, replace switch.
3.
Gas valve defective – Stuck in closed position. Clean or replace gas valve.
