Gas Furnace Intermittently Not Lighting Up

manny77

I have a Weil-McLain EG Gas Boiler.

On Sunday and again last night the gas would not ignite despite a signal being received from my ecobee 3 thermostat (i hear a click sound). last night i tried after a couple of hours and it worked again.

Any idea what could be causing this?

manny77

Here are some pictures of the boiler and wiring.

Abracadabra

Does pilot ignite?

If not, troubleshoot the ignition control, verify there's gas..

If you're not familiar with this stuff, I'd call a pro

Tim McElwain

You have an intermittent pilot system. On the S8610 control see if you are getting 24 volts when the thermostat calls for heat. You should have 24 volts at TH and 24V GND if not check external controls, If yes then are you getting 24 volts at PV and MV/PV if so and the valve does not allow pilot gas and the spark ignite the gas then make sure you have 24 volts at the gas valve. If yes then if pilot lights youi should have 24 volts at MV and MV/PV.

JUGHNE

First question: does your vent damper open when T-stat calls?

Fred

Also, when was the last time that Pigtail, (looped pipe) under the Pressuretrol was taken off and cleaned? They get clogged with gunk and can hold a little pressure between the Pressuretrol and the clog, causing it to hold enough pressure to not drop to "Cut-In" pressure for a while. Eventually pressure will drop enough to allow the boiler to fire.

manny77

Thanks all for the feedback. There is gas because the system does work.

I will look at the suggestions when I reach home tonight and if needed will call an expert.

My guess is that Fred's last feedback re: Pigtail could be the answer. It has not been cleaned in about 2 years.

manny77

Wanted to post an update on this.

It turned out that the pilot ignition switch was faulty and needed to be replaced. Was charged $650 to replace for a $100 switch but we have heating again.

Steamhead

We do NOT discuss pricing on this forum.

Tim McElwain

Not sure I know what you are talking about on your system. What is a pilot ignition switch? You have a module that provides spark to the pilot are you sure he did not replace the pilot????

Abracadabra

Tim McElwain said:

Not sure I know what you are talking about on your system. What is a pilot ignition switch? You have a module that provides spark to the pilot are you sure he did not replace the pilot????

@Tim McElwain i'm guessing he means the ignition control

manny77

This was replaced - http://www.supplyhouse.com/Honeywell-S8610U3009-Intermittent-Pilot-Control-4584000-p?gclid=CMrHzdX6tdECFRZYDQodFkIDHA

Tim McElwain

What was replaced was the Module which controls the electronic operation of the system. They are not cheap!

manny77

It is cheap if you compare to the labor cost!

JUGHNE

That was less than I paid to get the heater working in my 20 year old pick up. ($45 part).