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Replacing S8600F with S8610U on boiler. No LED, No ingnition

I have a crown boiler and recently replaced my honeywell aquastat relay and the gas valve. My boiler worked for one week and then we weren't getting a spark. Checking the flow of current, we determined that the ignition control module was not working so I bought another one for replacement. I bought a S8610U as a replacement for a S8600F. After installing, I get no light on the LED indicator nor any spark. I have a plug connector for the MV, MV/PV, and PV so that is connected properly. When I connect the 24V(gnd) and the 24V, I get 24V's on my fluke when touch my probes to each of the terminals. When I have the 24V(gnd) and the TH-W connected, I get 1.6V on my fluke. Regardless of which pair I have connected, I do not get a spark at the "spark" terminal. I have followed a couple of posts and videos for checking spark intensity and do not get an arc.

In case you are wondering. My system is calling for heat. My aquastat cycles, the circulator is pumping water through the pipes, and the damper has moved to the open position. At that point we are getting voltage to the module but it seems like it dies there.

One thing that is confusing, is that the installation instructions state and the wiring diagram shows connecting the TH-W. The wiring diagram shows the TW-W connected to the hot(L1) inline with the thermostat, but my thermostat is connected to the relay so I am not sure if that is part of the problem.


  • solradman
    solradman Member Posts: 58
    Installed a couple a year or so ago, I believe I ended up connected power from the stat to the 24V terminal not the TH-W to make them work.
  • unclejohn
    unclejohn Member Posts: 1,833
    See if the power to TH and grd. will operate a 24v relay and thing like a 90-340 relay. If it pulls the relay in the igniters bad. If it won't the aqua stat is bad.
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    Could be that the igniter is actually bad, not the controller.

    When I replaced mine, I changed out the whole pilot assembly which included the igniter and integrated flame sensor. Change the cable too.
  • Tim McElwain
    Tim McElwain Member Posts: 4,628
    edited November 2017
    Give the full numbers of the aquastat relay you installed and the one you removed (why was it replaced?) and does the S8610U have terminals for testing microamps directly off the control? These identifications are necessary so I can direct you as what to check.

    There should be no connection to 24V unless you have a vent damper. You should have connections from the"C' circuit on transformer (B2 on relay) to 24GND and from "R" to THW (B1 on relay).

    Did you leave the terminal on the module for a vent damper plug in empty? If you plug anything into it other than an actual vent damper you will damage the control. You should not transfer the dummy plug from the S8600F to the S8610U.