"Gunner" wrote in message
...
Ive got a problem with a water heater at work. This is a natural gas
unit used to boil water out of oil for reusing the oil

Controller is a Honeywell S89F controller. Everything checks out
normally..sorta

Unit is powered up, gas on.
35 second prepurge cycle starts

At this point, for 4 seconds the ignitor fires up, the gas solenoid is
supposed to open, and then run for a few seconds to allow the flame
sensor to stablizes (DC rectification through the flame) then run. If
no flame, its supposed to recycle another 3 times then lock out if no
burn is detected.

My problem

When the solenoid voltage for the gas valve comes on..it makes and
breaks 3-4 times, or simply comes on then quits within a second. If
the flame actually does fireup, it may trigger the solenoid on and off
click click click for the 3-4 seconds, then shuts down sometimes it
only clicks once. It may or may not go through the following 3
recycles.

Ive checked the ground, cleaned all the grounding connections, double
checked the ignitor via jumper and still I cant figure out whats
causing it to not come on and stay on. Input voltage is constant, the
24vts to the controller is constant, etc etc.

I put a DC milliamp meter in line with the flame sensor rod, but was
unable to get any reading in the second or two that the flame actually
did come on.

Do I have a bad flame sensor or a bad controller? The flame sensor
appears to be in the proper position from the burner face, and the
flame sensor lug does appear to have 110vts on it, measured to ground.

Any ideas? My gut instinct is a flaky controller, but the entire
blower unit was removed and taken to the dealer where it did work
properly, its alleged by the staff.

This is the manual for the unit
http://hbctechlit.honeywell.com/tech...0s/68-0066.pdf

Gunner


"Gun Control, the theory that a 110lb grandmother should
fist fight a 250lb 19yr old criminal"

What's the gas pressure to the unit? I installed a new furnace a few years
ago that wouldn't fire the main burner. Turned out the pressure was slightly
higher than the valve could take. Old furnace worked fine for many years at
the same pressure....Paul