Weil Mclain boiler won't fire:

bushleagueMarch 7, 2009

Okay my circa 1990 Weil Mclain HE-4 gas boiler refuses to fire. I changed the hot surface ignitor a month ago with no problem and it has been firing fine until today. The ignitor glows and you can hear the relays for the firing sequence, then one more click and the ignitor shuts down. The blower runs fine, and the vacuum appears correct, the gas is on at the meter (I have no other gas appliances). Any ideas here? Oh and the HE-4 does have the flame sensor mod and the ignitor is angled down app 15 degrees toward the gas tubes. Thanks!

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mr_havac

Do you have 24 volts at the gas valve terminals after pre purge?

    Bookmark   March 7, 2009 at 8:53PM
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bushleague

mr hvac I wasn't getting 24 volts anywhere leading me to believe that the transformer had failed. I reseated all of the terminals on the brain box (white-rogers) then gave it a few taps with my screwdriver handle and it fired. After about two minutes the flame went out, and with the blower still running, fired again. The boiler has always done this, especially when calling for heat. Conversely I have an HE-3 in an income property that pedals like crazy without stopping until the thermostat is satisfied. I would imagine this is a function of the controls, specifically the brain box and not the boiler itself. I did find similar related complaints on a diy forum, and reference to a Weil Mclain brand updated controller.

    Bookmark   March 8, 2009 at 9:29AM
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