Igniter Stays Lit - won't turn off


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Old 03-29-11, 11:07 AM
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Igniter Stays Lit - won't turn off

The title says most of it - my igniter is staying on. The whole story is this:
My 19 yr old Comfortair furnace was shutting itself off after lighting. I cleaned the temp sensor but in the process broke the igniter. Don't ask. I don't think it was already broken. I replaced the igniter with a Honeywell silicon nitride igniter. Furnace fired right up and appeared to be working fine until I noticed it wasn't on and the igniter was lit. Shut the power off and it did it again later. Igniter stays on.

Any ideas? Thanks.
 
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Old 03-29-11, 12:41 PM
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Are you saying the ignitor is staying on even when there is no call for heat? If so, you likely have the ignitior wired wrong.
 
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Old 03-29-11, 02:59 PM
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Grady - Thanks for the reply. I just reversed the two wires and it's still the same. Yes, the igniter is lit with the thermostant on fifty degrees. I turn the temp up, the gas comes on and lights, the blower is on. It seems to be functioning normally except the igniter is always glowing.

What's odd is that the original problem seemed to be the temp sensor. It was shutting down after lighting. After cleaning it's not doing that.

The igniter is a universal igniter. If I had the wires somehow not making contact right or reversed as you said, would it stay lit?
Thanks again.
 
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Old 03-29-11, 03:23 PM
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What is the make & model# of the control & to which terminals is the ignitor connected?
 
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Old 03-29-11, 04:11 PM
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General 90
InterCity Products
Model 50A50 T110

White wire is connected to IGN N (neutral side?)--- Black to IGN on Hot side. That has not changed.

These wires run from the control to a plug in connector on the top side. The ignitor side (male I think?) says Norton, the original igniter I guess. My previous igniter was a White Rodgers which was put on by a tech who must have cut the norton wires and left the plug in connector. So, my new igniter is connected by plastic screw on connectors to those two old wires as was the White Rogers igniter.

I hope this makes sense.
 
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Old 03-29-11, 05:07 PM
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If you turn the thermostat to "off" does the ignitor go out or do you have to turn off the main power to the furnace?

The only way that ignitor can glow is to be supplied power (120 volts). The composition of the ignitor itself (silicon carbide or silicon nitride) matters not. Since the ignitor is connected to the correct terminals the power has to be coming thru the control when it should not.
BTW, those ignitor wires should NOT be connected with anything other than ceramic wire nuts.

I've never heard of a nitride ignitor causing a problem with the controler (made for silicon carbide ignitors) but I guess it's possible. Maybe the Si-N ignitor draws more current than did the Si-C & welded a relay.
 
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Old 03-29-11, 05:38 PM
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I just tried the thermostat on off and the ignitor still stays lit.

And my terminology was just wrong - they're ceramic wire nuts.

I have everything, including gas, turned off and I'm going to sleep on it. At least the weather is finally getting warmer. I won't need the furnace soon.

Thanks very much for your help. I'm going to take another look tomorrow.
 
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Old 03-29-11, 06:19 PM
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The relay in the control is stuck closed. You will need to replace the HSI controller. 50A55-843 is a universal white rodgers board and should replace your current control. a picture of your current control would help me verify.

If 120V is going to the HSI with the stat off then the relay is bad in the control. Could be total coincidence. If it is a 50A50 control then you cant wire it wrong. it is a molex connector on the board.
 
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Old 03-31-11, 04:55 AM
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Thanks hvac and grady. I'm still here. I haven't had time for the furnace. I see the White rodgers controller is about $90 on amazon, which would be a reasonably priced fix. Honeywell also makes a universal. I'd have to look further into compatibility. I'm starting to wonder about my ability to install it. I guess it's just connecting wires, but I have no experience with this. I'm sure a pro would be $400 or so.

I'm also wondering about the life expectancy of my comfortmaker furnace and whether the gain in efficiency would justify a new furnace. Mine is 20 years old. No, I would not install it myself.

I'm sure the $90 fix will look good when I see furnace prices.
 
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Old 03-31-11, 07:33 AM
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With the White-Rodgers the installation is really easy. Pretty much plug & play. The Honeywell isn't bad but some connections might be in different places. In my mind it's hard to justify replacing the furnace for a $100 part. If it were a $300 washer or dryer it would be a different story.
 
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Old 04-12-11, 08:20 AM
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I'm back. I think I'm ordering the White Rodgers 50M56U-843 Universal Single Stage HSI Integrated Furnace Control Kit. It They call it the one kit that replaces them all. It comes with a nitride ignitor. On the chance that the new honeywell ignitor killed my last board I'll use the new one.

Unless someone yells at me not to use this board I'm ordering later today. It does look to be plug and play but I'm sure I'll be back when I'm installing.

Thanks
 
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Old 04-12-11, 10:25 AM
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The only problem I see is possible physical size. If you have room for the larger control, I know of no reason not to use it.
 
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Old 04-26-11, 01:37 PM
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I have a new White Rodgers 50m56-843 control. I just labelled all of the wires connected to the old intercity control.

Question: The neutral side of my old control has labelled - Cir,xfmr, line. The new control does not. The neutral area has connectors labelled e17 thru I think e21 above the four plug ind ign plug. Nothing specifically labelled.

Are the neutral spade connections all the same? Can neutral xfmr, for instance, connect to any of those "e" spots?

The other difference is the new control has low and high heat. Old does not. Not sure which to use.

Thanks in advance.
 
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Old 04-26-11, 05:39 PM
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On most controls neutral is neutral & which wire goes where matters not. As far as the high & low heat, I suspect it is for 80 & 120 ignitors but I'm not sure. The installation sheet has nothing to say about it?
 
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Old 05-05-11, 12:07 PM
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Yes! I think I'm done. Neutral spade connections are all equal. Hi/low is solved- low gets a park for continuous speed.

At first I plugged the old 12 pin connector directly in the new control and the flame sensor kept turning the gas off. I finally figured out I had to use a harness that came with the control. Old 12 pin connects to the harness which runs the flame sensor to a spade connection and the other wires to another 12 pin connector.

In any case - I'm working.

Thank you so much Grady for the help, and hvac. This site is great.
 
 

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