- Inspect the pilot orifice or clogging or apparent damage. If necessary, replace the orifice -DO NOT attempt to drill out the orifice.
- Check the electrical system for a good system ground through the pilot burner gas tubing ' You can use a jumper cable (with alligator clips). Connect one end of the cable to the pilot burner bracket and the other end to the gas valve -if the system then operates, you have isolated the problem to a bad or insufficient ground.
- If none of these checks surfaces the system problem then replace the ignition assembly (Q 3400 a 1024) At this point the system should operate properly -if not -replace the Smart Valve.
To correctly diagnose system problems in Smart Valve products you should have a digital multi-meter or an analog meter -either of which should be able to measure one-tenth of a micro amp ( .0000001 amps / dc. )The meter should also read ohms resistance down to one tenth of one Ohm (.01)
The resistance of a Norton silicon igniter used in the Q3450 or Q 3480 pilot assemblies, when new and cold, will be between 3 and 4 Ohms (average 3.7 Ohms) as the igniter ages the resistance will increase. When its resistance reaches 10 Ohms the igniter should be replaced
A test harness for use in making micro amp readings while the system is working is available through your Honeywell distributor -the part number is 395466 Smart Valves Generation 1 will need a minimum reading of .0000003 micro amps (Three-tenths of one microamp).
Generation 1 systems can be easily identified by the rotary gas cock knob on the top of the valve. It will also have part numbers SV 9500 or SV 9600 Generation 2 systems or later can be identified by an electrical slide switch on top of the gas valve. This slide switch electrically opens or closes the gas flow circuit in the valve and replaces the rotary gas cock. Generation 2 valves are the direct replacement for both generation 1 and 2 valves.This test harness also will allow you to easily convert microamps to kilovolts. The minimum value you want for a microamp reading on generation 2 systems is 2 (.000002 A). Most importantly is the need that the microamp signal, on either system, be a steady signal. A wavering signal indicates that the pilot flame is not playing on the flame rod steadily -the flame recognition time is less than 2 seconds -and nuisance shutdowns will occur. Check for drafts across the pilot.
Source: Honeywell
by Ron Walker