Oil Burner Furnace / Relay Chatter

[wingardclocks]

Have a 20+ yr.old with a Wayne burner. Sometimes, but not all the time during start up the thermostat relay chatters (on/off-on/off-on/off etc...), then it stops and runs smoothly. Occaisionly this will occure in the middle of a cycle, but rare compaired to start up.

I justed serviced burner. Nozzle, filter, cleaned electrodes & gaped, cleane electric eye (cad), set nozzle to mixing plate distance, everthing to OME specs.

It even does it with a jumper on the T-stat terminals. Could it be the cad? How do you test these? I know it is dangerous, but can you temporarily jump the cad terminals to diagnos?

[HayZee518]

jumping the photocell won't help you because its resistance is varying and so this signal is fed to the burner relay. actually it is producing a dc voltage to the electronics of the relay. no voltage there no woikee! relay goes into lockout.

[wingardclocks]

So what do you suggest?

[HayZee518]

first check the heat anticipator on the thermostat. its setting should coincide with the current rating of the burner. next change the cad eye. shouldn't cost much. if your burner is a tankless hot water heater check the aquastat. it may go directly into the tank or may use a dip tube in the tank. check for loose connections on the burner relay.