Gas valve noise

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Old 11-26-05, 07:47 AM
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Gas valve noise

After fixing my Carrier 58gs100ga furnace with a new fan board and for good measure a new ign sparker/lockout, I noticed a couple of things. The sparking quits sooner, then the gas valve opens faster, without as long of a delay until I hear the main gas valve click. (White Rodgers 36e93) But I also hear a "chatter" in the solenoid/valve--brief, less than a second, like a slow buzz, and wonder if the gas valve is dying? Doesn't seem to be every time, but not the quick and sure "knock" sound of before. Could the board or ign' lockout be hesitating the connection or something? Thank you.
 
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Old 11-26-05, 09:33 AM
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Is this a 5 wire valve (just count wire terminals on valve) and a 3 wire pilot?
 
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Old 11-26-05, 10:34 AM
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yes exactly, but one of the terminals #3 bottom most spade lug is empty.
 
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Old 11-26-05, 06:36 PM
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If this is the original valve that noise happens a lot. I've seen many many do just that and they kept on cooking
 
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Old 11-26-05, 09:03 PM
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Yep she's on the original 13 year old, I'd hate to get frozen in February---do you think I should get a new one or is the noise common but not a failure mode? Any guesses as to how she's got?
 
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Old 11-26-05, 09:56 PM
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Thats kinda a loaded question.. I would think peace of mind is worth something, if thats how your personality works. You never know it could go forever or the new one you install could poop out in a week. Hows that for dancing around the question
 
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Old 11-27-05, 08:49 AM
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I think I'd go for the new one, but I didn't know if the valve was the cause on its own, or the new sparker/lockout or new fan board was rattling initially the signal to the valve. Any guess?
 
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Old 11-27-05, 09:38 AM
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This is what I would do:

Turn off furnace switch.

Unplug the wires on gas valve.

Use an analog volt meter ($15-20 at home improvement stores or Radio Shack) and test each wire to ground, with meter set to 50 vac volt test (as the gas valve works on 24 vac). Run furnace and when ignitor goes, really start paying attention to the reading about to occur on each wire you test, one at a time, from that wire to ground (any metal on furnace will do. Without using a jumper cable attached, like I would do, you may need an assistant to hold onto the detached gas valve wire so that you can more easily touch one probe to the wire they are holding for you, and then touching the other probe to the metal furnace (has to be something unpainted.) If you start getting needle fluttering, like your clicking sound you say you get, then obviously the problem is not in the gas valve but is probably a fault in the board, instead.

Now this is where the testing gets more complicated. If you have pilot ignition and the problem is with the burner flame only, let's say, and not the pilot flame - you have to remove only the MV marked gas valve wire. You won't get a reading if the PV wire is disconnected because that funcion has to be intact and running before the current can be sent to the MV (main valve) wire. I guess that's not too complicated - eh?

But I am going to complicate it more. This still won't prove the board is bad if you have pilot but let's say eradic needle behavior for the MV wire volt test between that wire and ground. Here is how:

IF the pilot does not adequately send a signal to the board that the pilot is good enough, it will not allow correct, if any, voltage to be sent to the MV wire! You have to physically make sure that your pilot is generating adequate flame to heat up the built-on sensor that sends this signal back to the board

In brief, to have gas valve failure with a flutter click at the valve is rare, IMO. I would have to suspect either the entire pilot assembly and/or it's flame sensing ability has fault, or it's in the board.

There may be some milliamp test one can do at the board to see if the board is acknowledging pilot flame. But I, like you, would have to consult with my furnace guru on this, and maybe I will do just that so that this could help even me, when I work on spark ignition/pilot furnaces.

I know quite a bit, but don't know everything, and enjoy working on and learning all about these things. I know enough to that when I don't know something, I know the correct questions to ask. I am at a stage wher I am never completely in the dark, regarding electrical, furnaces, appliances, etc.
 
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Old 11-27-05, 10:20 AM
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Thank you for the detailed answer. To make it more clear, the pilot lights on the first spark the sparking then slows and stops within 15 seconds. Then the rattle for less than a second, a delay of 4 to 8 seconds and then the flame roars to life. The 4 to 8 second delay is described in the normal operation of the valve.

I noticed that the flame heating the spark electrode is a little jumpy, sometimes the clear non-ionizing area of flame is in the electrode tip, but mostly the blue part. The pilot flame seems a little large. Maybe I should adj the pilot pressure slightly. But it never sparks again after the first sparking cycle, so I think the pilot has 'proved' and the sparking board is "satisfied."

Can I just put the two test probes across the main gas valve terminals #1 and #3 according to the scematic)? According to the scematic, #3 is jumped to #2 of the pilot.

I can put in the old ign board, which I think was working properly and see if any difference also. Suggestions?
 
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Old 11-27-05, 11:17 AM
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I used my analog vom with full scale reading 25 volts across the main gas valve terminals reading AC. Wouldn't you know it this time it was a nice smooth sweep to full scale and a single "click" no rattle. I'll watch it. I also, though, after watching this normal click, adjusted the pilot a little down, so that the sparking electrode tip was cherry red and always in blue--I assume this is correct but please advise me. Thank you again.
 
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Old 11-27-05, 05:15 PM
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It sounds like everything is close to working right - all except for that 1 second chatter-buzz (or whatever). Maybe it is some quirk where, due to the pressure of the gas coming out of the pilot (you said you think it is rather large) that this is causing some sort of flutter in the valve. You have nothing to lose by adjusting the pilot screw. Just pay attention to where the slot is when you start and how much you turn it, so you can always go back to the way it was, if it won't stay lit. Then see how the sound is in the solenoid of the gas valve.

Just be aware, and don't blame me, if you cut corners too much, the ignition control board stops sensing pilot, and the furnace goes out. High efficiency furnaces seem like there is more to go wrong, and if the ignition source goes out, or the flame sensor no longer works, or............ You just have to be aware of this and if you ever go on a trip in the winter, it is adviseable that you shut off the water main, turn off your water heater, and have a friend stop in and make sure your furnace keeps working. Houses have been ruined by water from furnaces going out when people are on trips!
 
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Old 11-27-05, 05:27 PM
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Mitchella

Since the meter made a nice smooth swing to 24 volts & the gas valve did not chatter, I have to believe you may have a dirty terminal or connector. It is also possible the pressure from pushing the probe against the terminal caused a good connection internal to the gas valve. Adjusting the pilot may also be the key. Things like this can be darned tough to track down.
 
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Old 11-27-05, 05:43 PM
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I watched it work perfectly once again and then on the third time, I think the meter made a nice smooth swing, but it chattered. I thought the same thing about the probe pushing on the terminal too, Grady. I will remove/clean/tighten the connections. I made sure the spades were snug on the blower board.

I have a question about the operation of these three wire pilot sensing devices. I read a piece about the ionization creating a small voltage for the ignition board to sense, but is it the wire getting hot/red hot or the hood that directs the flame toward the burner that is "sensing?" I cleaned both with steel wool and meticulously set the gap for the electrode as per the manual when I replaced the boards. I notice that before the main burner kicks on, the flame is steady and smooth, but when the burners kick on, the pilot is jumpy and a clear central area of the pilot flame dances on the wire electrode intermittently. I do not know if this is normal, I really didn't study it much before all this started. I turned down the pilot so that it is less jumpy and now while the main burners are on, the electrode gets red hot. Before the main burners ignite, it is only slightly glowing when the board(s) kick on the main burner.

Is it the blower board or the sparker/lockout that is responsible for signaling the gas valve? I get confused when I read about the sequence of operation with the pick/hold/pressure sensing blah blah!! Thank you again.
 
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Old 11-27-05, 06:00 PM
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Another thought

Another thought just crossed what little mind I have left so I thought I better post before it was history. Often a loose or dirty ground can cause the same symptoms. Check all the grounds related to the furnace, all the way back to the panel if need be.
I don't fully understand this type of flame rectification either but I believe the current travels thru the flame from the rod to the hood. It can be checked with a micro-ammeter but different furnaces require different amperages & I don't know what yours needs. If you post the # of the ignition module maybe I can find out.
 
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Old 11-27-05, 07:23 PM
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I always hear the "you're the only one; nobody ever said/experienced that before" story. With all of your experiences I was hopeing for a 'Oh yeah I hear that all the time, its the ...."

Here's a thought I had: I read a post where a new heater installation wouldn't ignite, turned out to be a switched L1 and L2, something about the rectification. I didn't do that, but the two secondary wires off the new transformer were both black, and I don't understand anyway how after the windings are separated in the transformer and it's AC, how it could matter if the sec 1 or sec 2 were switched. Does/Could it make a difference????

This thing sounds just like the old buzzer door bells, a brrr sound. I had an old gas drier valve with a similar but constant sound, it was the solenoid on the valve. I'll monitor it and even swap out the old sparker/lockout, I guess swapping it out could let me know it wasn't the new sparker/lockout board if the same thing kept happening. Thanks again, I'll post back with any news.
 
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Old 11-28-05, 10:00 AM
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I guess I should have mentioned the obvious(for a tech) that a clean pilot is a must. The flame must be impinging on the bimetal strip. Transformer secondary wires don't matter on this furnace
 
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Old 11-28-05, 10:10 AM
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Thank you MBK3; I think your original diagnosis at the beginning of this thread was proabably right on. I asked WhiteRodgers tech support, he said the noise isn't uncommon and happens when the solenoid plunger gets worn and is finding its seat when wacked with the 24vac. He said it really didn't predict failure, which could happen anytime, and also that the design is for 15 years (mines 13). he doubted the boards would do it. I might replace it, but I'm thinking of a new furncace/AC all together so maybe I'll hope for the best. Which brings me to a new question about heat exchanger life.....

And to Ecman1, I going to hook up an extra 24vac relay inparallel with the gas valve to listen to and a 24v bulb to watch so I can get maybe confirmation that the initial signal is solid. Wish I had an oscilloscope.
 
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