8910 honeywell question for Bill W

Steve Ebels

I have a Smith GV-100 that's driving me crazy. The HO has had two other techs in before me and they've given up in despair. The problem the boiler exhibits is random lockout. By random I mean from 4-5 a day to one in 2 weeks. The control is an 8910 using the 4 second trial-3 retry chip. It has obviously been retrofitted as the Ram electronics control that came with the boiler is laying alongside on the floor. Whoever did this added a relay to power up the inducer on a call for heat also.

Here's what I found while just sitting and watching it for an hour and a half this afternoon. (The 4th time I've been there.) HO says whenever it locks out you have to let the boiler sit with the switch off for several hours then it will relight. While I was watching it cycle I observed that the "heartbeat" pulse of the light on the 8910 would hiccup for lack of a better word. The steady bright dim, bright dim was replaced by bright dim, brighter and then bright. About 5 seconds after this the flame dropped out while still under a call for heat. The control never quit the bright dim pulse while it cycled through the timing after a flame failure, prepurge and ignitor warmup. It lit up on the first try.

All voltages are good. Milliamps read good. The flame rod is clean. Gas pressure is spot on. Burners are in good shape. The flue sections are as clear a -20* night in February. WHAT THE HECK IS GOING ON WITH THIS THING!!!! The HO is ready to blow a gasket and I'd really like to help him out. Suggestions anyone????

Floyd

Heat????

Is the control mounted on the side of the cabinet or right on the sheet metal next to the boiler casting???
Sounds like maybe it heats up and then has to cool down for it to come back on.
I'd maybe take the sucker off and lay it out away from the boiler and see what happens.

Does the x-former voltage vary prior to shutdown???? Would have to have a digital meter and be watching when it happens....

Just a couple of thoughts!!!

Floyd

Steve Ebels

Thanks Floyd

I moved the control the second time I was there. It was mounted right on the panel above the burner and I thought that may have been the problem. The Xfmr output voltage stays between 25 to 25.8V. Nice and steady.

Thanks for the suggestions

BillW@honeywell

S8910

Hi, Steve! If this is an S8910U1000, it sounds like either you have a bad ground, a wiring problem,interference or the control may be bad. Normal "heartbeat" should be visible during a call for heat, and continues thru all phases of ignition; prepurge, warmup,ignition trial, between trial purge, and normal run. One flash means that it has gone into ignition lockout mode. It seems you have checked everything, but this sounds like a wiring or ground issue, or something else on the boiler is interfering with the control. If you can send me a fax number, I'll get the cut sheet to you.