Boiler Burner Won't Light

Andy Stern

Andy Stern

Boiler Burner Won't Light

I have a Slant-Fin GG-100 boiler with Honeywell intermittant spark pilot ignition (S86 module). My pilot burner sometimes flares continuously for long periods, but the main burners don't come on. Sometimes the igniter sparks continously for long periods and the pilot flame never lights. Sometimes everything works fine.

I replaced the pilot ignitor assembly hoping it was an air mix problem, poor flame shape, ground problem or somesuch issue that would prevent flame proving. I swapped out the ignition cable so I'm resonably sure it's fine. I'm open to ideas as to what to look at next. I had assumed that the gas valve would either work or not and the module could be the culprit, but I'd like to solve problems by diagnosis and not parts swapping.

Andy...

CHARLES_4

Hmmm...If the pilot assy and cable have both been replaced, the next stop is the spark module. BUT you should check for PV/MVPV voltage when the module is sparking and the pilot's NOT lighting. No voltage--bad module. Voltage to valve/no gas--bad valve. If you're not sure if you have gas when the module is sparking, crack the pilot tubing connection or try lighting the pilot w/match. If any of this is too confusing, either call for a service tech or get back to us when you get out of the hospital...

BigRed

Hospital!!

Hospital is rignt good luck with the match

Empire_2

Charles has the idea...

Has the unit been serviced lately? Almost sounds like the pilot adjustment screw is too hi. Blasting out to much gas. Have a technician in to look at it. That's your best bet...

Mike T.

Mad Doctor Q

Burner won't light

make sure the ground wire is securely connected from the GND burner connection at the S86 directly to one of the two screws on the pilot/ingitor assembly and nowhere else. Check the connections from the S86 to the Gas valve that they are connected in the right place. The ignitor assembly comes with an orifice cone that controls the size of the pilot flame, make sure it did not fall out of the bag or the ignitor or you will have a large pilot flame that will soot the electrode of the pilot assembly and insulate it, interrupting the spark signal back to the S86. If the pilot is lighting but the main burners are not you may need a new gas valve. While we're at it when was the last time you had the inside of the boiler look at? These boilers without adequate air tend to soot up which wil lead to flame roll out (check for rollout switch which I believe is a standard part on these models). Yes, gas boilers soot up without proper air. Q!

Andy Stern

Problem Solved !!!

I want to thank all for the help. The real problem was the off and on nature of the problem. SOmetimes it worked, sometimes not. When it works all seemed OK, when it didn't I sometimes did not have voltage to the gas valve pilot and sometimes I did but didn't have voltage to the main valve solenoid. The pilot assembly has no separate ground (it's grounded thru the frame), but I had cleaned all mating surfaces an metered the resistance prior. Pilot flame was fine and everything clean burning. The give-away was when I did some percussive maintenance testing... tapping the S86 brought it to life for a bit. Changed out the S86 with the newer generic model (requiring some head scratching as to where the 24v for damper hooks to), and all's well. Opened the old S86 and found bad relay. They must be in series.

Thanks for the help.. This think tank brain trust is great!!!

Regards,
Andy