Boiler will not light - Electronic Pilot

yorks6988

I have an electronic pilot light. I get good flame from it but it does not seem to be tripping the flame sensor. I tried cleaning the sensor and still no luck.
I am thinking to replace the pilot assembly and know the part number. Honeywell Q3481B-1644
I was wondering if I need that specific one (3 days to get here) or if other assemblies will work. I have looked at quite a few and they share the same bracket and wiring.

109A_5

Hello @yorks6988,

yorks6988 said:

I get good flame from it

Without being there it sounds like you want to replace the part that works. Is the flame insufficient for proper flame detection ? Is the flame sensor positioned properly. It sounds to me like you need someone to properly troubleshoot the situation. It could be the sensor's wire, the sensor's insulator is compromised, a poor ground, poor connections or the ignition module too.

Anyway, if you can't get the correct pilot assembly something that is very close MAY work but there may be other issues. I would get the correct part. After I found the actual problem.

EdTheHeaterMan

The flame sensor portion of the pilot assembly connects to something else. what control does the white wire connect to? .

The way that Flame Sensors like this work is:
1. A 6000 volt spark jumps from the white wire to the electrode rod and jumps across the air gap where the gas burner has pilot gas exiting.
2. Once the raw gas and air mixes in the pilot burner and intersects the spark the flame ignites.
3. Then a very low voltage AC current signal is sent out by the same control thru the white wire.
4. The flame acts as a rectifier and changes the AC voltage into a DC signal by the design of the Small electrode and the Large flame Hood and the additional grounding bracket. I'm no electronics genius but I know that this happens when the electrode is clean (and you already said that you cleaned the electrode) and the pilot burner is properly grounded to the control.
5. The DC rectified electrical signal then returns to the control by way of the chassis ground. (all the metal screws from the pilot burner to the control must have no corrosion).

I have come across some boilers and furnaces in damp basements where all the metal screws that connect all the metal parts have some rust or corrosion. When this happens, I get a copper wire and put new solderless crimp connectors on each end and connect one end of the wire to the pilot burner. Then I take the other end of the wire and place it on the control Ground Terminal. If your control is not equipped with a ground terminal than one of the screws that attache3s the control to the heater has a ground strip or wire under the cover that makes the control ground the the chassis.

I would check for proper control grounding before I start throwing parts at it.

Mr. Ed

EdTheHeaterMan

The flame sensor portion of the pilot assembly connects to something else. What control does the white wire connect to? .

The way that Flame Sensors like this work is:
1. A 6000 volt spark jumps from control to the white wire to the electrode rod and jumps across the air gap where the gas burner has pilot gas exiting.
2. Once the raw gas and air mixes in the pilot burner and intersects the spark the flame ignites.
3. Then a very low voltage AC current signal is sent out by the same control thru the same white wire.
4. The flame acts as a rectifier and changes the AC voltage into a DC signal by the design of the Small electrode and the Large flame Hood and additional grounding bracket. I'm no electronics genius but I know that this happens when the electrode is clean (and you already said that you cleaned the electrode) and the pilot burner is properly grounded to the control.
5. The DC rectified electrical signal then returns to the control by way of the chassis ground. (all the metal screws from the pilot burner to the control must have no corrosion in order to complete the flame signal circuit).

I have come across some boilers and furnaces in damp basements where all the metal screws that connect all the metal parts have some rust or corrosion. When this happens, I get a copper wire and put new solderless crimp connectors on each end and connect one end of the wire to the pilot burner. Then I take the other end of the wire and place it on the control Ground Terminal. If your control is not equipped with a ground terminal then one of the screws that attaches the control to the heater has a ground strip or wire under the cover that makes the control ground to the chassis.

I would check for proper control grounding before I start throwing parts at it.

Mr. Ed

yorks6988

I did try to jump the ground wire and no success. But now, when I turn on the main power the Cycle Gard is clicking like a geiger counter. It finally settles down and then tries to light. I can also hear the gas valve clicking while it does that. After doing that the first time it only clicks a couple times when I cycle the power.
This is a video of it going crazy.
https://youtube.com/shorts/Grc0ffkFOlY

Jamie Hall

yorks6988 said:

I did try to jump the ground wire and no success. But now, when I turn on the main power the Cycle Gard is clicking like a geiger counter. It finally settles down and then tries to light. I can also hear the gas valve clicking while it does that. After doing that the first time it only clicks a couple times when I cycle the power.
This is a video of it going crazy.
https://youtube.com/shorts/Grc0ffkFOlY

It still could be a bad connection -- particularly a ground connection. Check ALL the connections and make sure they are clean and bright, and check the power ground and neutral all the way back to the circuit breaker panel.

109A_5

Hello @yorks6988,

Your video is private, no help there.
Starting to look like you have multiple system power related issues. A multi-meter may help if you know how to use one. Verify the power is good, 120 VAC and/or 24 VAC, if there is a Damper the end switch may be failing.

EdTheHeaterMan

The probe type LWCO is also a device that MUST have a good ground. The electrode is making a connection to the ground metal in the boiler through the water. Could the LWCO probe be dirty inside the boiler? For testing purposes you can temporarily jump the contacts bypassing the control.

dullknife1

Here comes the fireplace match guy again. Try to light the pilot as soon as the sparking starts. If the pilot lights and burner comes on then your pilot hood or spark rod has warped to close together. If this does not work we go to the next 

dullknife1

Keep your face out of the way. This is one of those don’t try this at home things

dullknife1

See the white wire between the 2 molex plugs in the top right? My board says pilot flame, a lot of boards just have  fs. Stands for flame sensor. Is your white wire connected?

dullknife1

Sorry.  Scratch the white wire connection.  Looks like a spark connection not flame sense.

yorks6988

Should be public now.
https://youtube.com/shorts/Grc0ffkFOlY?feature=share

So the red wire runs to the bottom of the ignitor. And if I understand correctly when it senses a flame it sends it down the tube to the green ground wire, which then tells the system there is good flame.

JUGHNE

If the chattering is from the cycleguard, (you could probably feel it on the front cover), I would suspect that control or loose connections inside it.

The pilot you have uses the spark ignitor electrode as the flame sensor also.
Did the original have only one wire on it?

dullknife1

I did not want to be first in because I missed that on the angle of that pilot the other day Also the OEM pilot angles left ,forward ,and right. The new pilot if it would work, looks like it angles to the left, or the right, whatever. But it does not appear to angle both left and right,and center And if the burners are a little dirty, which they probably are ,could be cause for concern  when that boiler fires up. 

dullknife1

As far as JUGHNE’s theory about a loose connection,I have this to say. I once saw a light show in a customer’s kitchen when the heater tried to turn on. Took awhile to track it down, but it was a “loose ground connection “in the breaker box. And yes, the light show was impressive. Check all your wire nut connections, with power off of course. Just make sure polarity is correct 

EdTheHeaterMan

You want to be looking for a bad connection in the Cycle Guard. It may be a dirty probe inside the boiler. It could be a loose wire in the control itself. To bypass the CycleGard temporarily place a jumper between P1 and P2. This will bypass the CycleGard from the circuit. If the burner operates properly, even if the CycleGard is still chattering, Then you know that the CycleGard is the source of the problem.