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Honeywell S8610M intermittent pilot control valve

_big_ Member Posts: 12
edited March 26 in Radiant Heating
I have a 21 year old Superhot SG-270.

It mostly works but occasionally refuses to fire for a random amount of time. I've observed that during these misfire periods, there is demand for heat, the boiler tries to light the pilot, but fails. Then there is about a 5 minute wait period for any accumulated unburnt gas to dissipate. Then it will try again. I've seen these un-light episodes last for an hour or two.

We've had periodic failures like this for at least a year. One of the strange observations I made was that the boiler is more reliable when I leave the front cover of the boiler off. Interesting.

Was investigating a non-fire episode yesterday, and I noticed that the pilot inspection hole cover plate was in the "inspect position" and not in the "cover the inspection hole position". Even more interesting.

The boiler room is a small closed room with makeup air vents. The makeup air vents are to an inside corner of the house exterior. And would definitely be influenced by wind direction.

At this point, I think the theory should be obvious. When the wind blows in the "right" direction, the pilot is blown out by the wind current. And while you might assume the front cover of the boiler would reduce these wind currents, its not a solid plate and could very easily direct the wind currents into the pilot inspection hole.

I've placed the inspection hole cover to the "run" position. And it ran fine last night. This is not necessarily conclusive, but is certainly evidence supporting the theorized root cause.

I have a couple questions for the HeatingHelp crowd.

Its possible we just didn't notice the problem, but It seemed to run fine for 18+ years. I'm wondering if the intermittent pilot control valve is aging and not throwing ignition lightning bolts like when it was young pup. Anybody know anything about the behavior of aging intermittent pilot control valves?

Is it possible the ignitor/pilot assembly has grown some low grade fault that is bleeding off lightning bolt energy?

The pilot control valve is a Honeywell S8610M. Apparently, these are no longer available. The Resideo VR8345M/Q/K is listed as a replacement. I would kinda hate to step away from the original equipment, but that might be necessary. Any comments about the Resideo?

This boiler is the sole source of heat in the house. Reliability is quite important. Would consider proactive parts replacements.


    EBEBRATT-Ed Member Posts: 15,510
    Resedeo is just made by Honeywell they just renamed it.

    I would remove the pilot assembly and clean it. Cobwebs dirt and dust and soot. A little bit of that can screw things up.

    Are you sure the pilot is not lighting or is it lighting and not being proven by the control? Makes a big difference in troubleshooting.

    Make sure you are getting 24v ac to the gas valve when the pilot tries to light. Make sure the pilot assembly is clean and screwed in tight . Inspect the spark cable and remove both ends and plug them back on a little corrosion can stop the spark.
  • Karl Reynolds
    Karl Reynolds Member Posts: 62
    The Honeywell S8610M on my Allied boiler gave up after twenty-one years. You can replace it with an S8610U3009. See page #2 of the instructions with the S8610U. You may need to set a switch or two. The VR8345 that you refer to is a gas valve. The new S8610U and a good cleaning like Ed recommends and you should be back in business.