1992 York Gas Heater- Will run, but takes a long time to start heating

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  #1  
Old 01-15-09, 06:32 AM
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1992 York Gas Heater- Will run, but takes a long time to start heating

I have a 1992 York gas forced air furnace.

In the morning the house is cold, in the 50s, and I hear something humming in the heater but the blower motor is not running and the gas flame is not on. I suspect thermostat told the heater to start hours earlier but it just hums and doesn't "kick-in"

If I turn the heater on and off a few times, I hear the hum for a while again, but it will eventually the flame will ignite and the main blower will turn on. Usually during the day I do not notice the problem.

Does this sound like a particular part is failing?

thanks in advance for any help!
 
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  #2  
Old 01-15-09, 07:45 AM
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Not enough info. to help you. Need more specifics on what is happening inside of your furnace. The humming is the inducer motor running etc..
 
  #3  
Old 01-15-09, 08:03 AM
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Originally Posted by Skip4661 View Post
Not enough info. to help you. Need more specifics on what is happening inside of your furnace. The humming is the inducer motor running etc..
Thanks for your reply. What info can I provide? I'd appreciate any help you can give.

The major parts that tend to fail that I am aware of in my heater are: ignitor and gas valve.

The thermostat seems to be engaging the heater since I hear the humming, but the process that causes the flame/blower to kick in either is delayed or intermittently will not occur.
 
  #4  
Old 01-15-09, 08:09 AM
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I'd start by taking the cover off the burner compartment of the furnace.

Post the model of the furnace off the rating plate inside the burner compartment, and the make and model of the ignition control. Are there any lights flashing on the ignition control? If so, identify the patterna dn post the diagnostic code for that combination if it's displayed on the furnace, which it usually is.

Then observe and record the sequence of events that happens when you turn the thermostat up. What do you see and hear happening? Post that entire sequence of events.
 
  #5  
Old 01-15-09, 09:31 AM
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I did what you described yesterday. It's a York model P30CD20N09101A (114000 BTU) I didn't see anything about ignition numbers. And I see no lights. I think this unit does not have any circuit boards or anything like that. (where I would see an error code)

When the thermostat is turned up, I hear a constant hum and often that's it. It may take 30+ minutes for the flame to start up and the blower to come on. While I hear that hum the ignitor is not red like it is when the heater is working properly.

Thanks for your help.
 
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Old 01-15-09, 10:32 AM
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Sorry, but I'm finding no references at all on the web for the model furnace you give. Where does the hum seem to be coming from?

The circuit board or ignition module may be in the fan compartment --- you'd need to remove the fan compartment cover to check. If there is a viewing port in the fan department cover trying looking through that for a blinking light.

Does this furnace have white plastic vent pipe or metal?



Do you have a multimeter for measuring ohms and volts and understand how to use it?
 
  #7  
Old 01-15-09, 10:41 AM
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This unit has a metal flue and it's from 1992 so it's probably pretty low-tech compared to newer units.

I'll try to give it a closer look when I get home.
 
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Old 01-15-09, 10:53 AM
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A furnace that age with a metal vent pipe is typically an 80% efficient furnace with a circuit board or ignition module with diagnostic lights to help identify problems. It usually has a hot surface ignitor that glows white hot to light the gas, and typically has a small fan motor above the burners to force combustion gasses through the furnace.


When the thermostat calls for heat, the first thing that should happen is that the small motor should start up and run. That might or might not be the hum you describe.

I'm presuming the hum starts when you turn the thermostat up, suggesting that the furnace has power to it and that the thermostat is working.

And you haven't said whether you have a multimeter and understand how to use it. Frankly, your skill level sounds minimal --- you may be better off finding a repairman to deal with the problem.
 
  #9  
Old 01-15-09, 11:04 AM
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I can use and understand a multimeter. I think I can handle the repair, although I don't have much experience with furnaces I've successfully repaired / installed my share of other devices.

My main concern is where someone who is not in the trade can get parts.
 
  #10  
Old 01-15-09, 03:00 PM
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Have needed details on my furnace problem

The ignition module is a White-Rodgers Model 50E47-070. I see the red LED and it was not on or flashing.

I held in the safety switch and had my wife crank it up to 80 degrees. Everything worked correctly. The induction fan turns on, the ignitor turns red, the flame comes on, and the blower turns on.

The problem is this does not always happen. If there's a fault that causes the LED to light, will it stay on so I can see it later, or do I need to always have the cover off so when it gets cold in the house (indicating the intermittent problem is occuring) I can go check the LED.

Maybe some of those relays are starting to fail, too. Any opinions? Thanks in advance!
 
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Old 01-15-09, 04:12 PM
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Yes, typically the diagnostic code will continue to blink until the furnace is reset by turn the power off or the thermostat down.

You might consider cycling the furnace through the ignition process repeatedly until it fails.


The practice of having your repairman turn the thermostat up, saying, well, it works, there nothing I can do --- that'll be $125 please, and call me again if it doesn't work! Is not one I like to encourage!

The correct response to an intermittent problem is to keep operating the equipment until it fails and the problem can be diagnosed an corrected, or at least that's my opinion!



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  #12  
Old 01-16-09, 05:43 AM
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good point. Another clue is that occasionally the furnace will over-heat the house by a few degrees but eventually shut off.
 
  #13  
Old 01-16-09, 08:46 AM
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A house that's overheating suggests a relay that's sticking, keeping the furnace on too long.

I'd start by using your multimeter to measure the voltage from chassis ground to both sides of the R and W contacts on the furnace. You should observe 24 VAC on the R terminal whenever the power is on to the furnace, and 24VAC on the W terminal when the thermostat is calling for heat.

If the house overheats and you still have power to the W terminal, that suggests a problem with the thermostat not shutting the furnace off reliably.
 
  #14  
Old 01-16-09, 04:57 PM
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here is a timeline

0 sec - turn on furnace - induction fan turns on
3 sec - hear click of relay - ignitor starts to glow
45 sec - hear click of relay - ignitor off

I was able to observe this several times. One of the times, at 45 seconds, the flame kicked in like it should.

What does this sound like? What conditions need to be present for the flame to kick in? Could there be an issue with a relay or a gas valve? Any other suggestions?

thanks!
 
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Old 01-16-09, 07:20 PM
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Hello there Torque,


You did a good job of observing and recording the sequence of operation of the furnace, which is perhaps the most powerful method of diagnosing a furnace problem.

That makes it relatively easy to narrow down where the problem lies.

What should happen is that the ignitor glows for 20-60 seconds, followed by the main burner gas valve turning on and the gas relased by the valve lighting off the hot surface ignitor.

That suggests a problem either with the electric gas valve not being turned on by the ignition module, a defective gas valve that's not turning on reliably or an unreliable gas supply that's not there to be turned on when needed.

The least like problem from what you describe would be the unreliable gas supply. Do you have other gas appliances, and are they turning on reliably, or are they operating irregularly as well?

The gas valve could be operating erratically, but that not likely either. But it needs to be tested --- do you have a multimeter that measures AC voltages? You need to connect your meter across the gas valve terminals so that you can observe when a 24 volt AC voltage is present across the terminals of the valve. After the ignitor lights up, you should see that 24 VAC present, and the gas valve turn on. If the voltage is present and you get no gas, you have a bad gas valve.

If no voltage turns on after the ignitor warms up, you very likely have a bad ignition module.

If so, post the make and model of the ignition module that the furnace may have.
 
  #16  
Old 01-17-09, 07:45 AM
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great info. I will do those tests. One question: could a faulty relay be preventing the gas from turning on or is that directly controlled by the ignition module? (white-rodgers 50e47-070)

And, I have a gas oven, hot water heater, and dryer and they are all fine.
 
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Old 01-17-09, 09:48 AM
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There probably is a relay for that on the ignition control module.
 
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Old 01-17-09, 12:01 PM
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SP about covered it.

Rather than speculate - test. See if the cklick you hear is from the igntor shutting off, or from the gas valve trying to open.

Grady has often suggested you can use a barbeque lighter at the burner, at that point when it clicks, and see if the gas fires off. Or if you have natural gas, see if the gas meter 1/4 or 1/2 foot dial turns at all at that click. If it does, then you could assume the ignitor is simply not totally shot but pretty close to it and the ohms measurement is now just barely too high to make it fire every time reliably.

You can test the resistance in ohms across the 2 HSI wires, with a volt-ohm meter (called a multimeter) after you unplug the 2 HSI wires, and see if you get some reading under 100 as you should. I have replaced weak HSI's that still glow good, and that has stopped your symptom for me. So this is not just theory. Therefore worth checking out.
 
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Old 01-19-09, 05:21 AM
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Thanks again for all the help. I will perform those tests, but I did some other tests yesterday.

If I am not getting voltage at the gas valve, does that mean my Ignition Control Module is bad? Or, are other components involved in delivering the 24 VAC needed to activate the valve?

I performed some tests and found that when the furnace was not working, I was getting 0 VAC at the valve. When it was working, the valve would get 24VAC at about 40 seconds after the heater is turned on. The problem is intermittent. (The heater USUALLY works)

Regardless of whether the heater ignited or not, I always had the induction fan running and the ignitor glowing, with the system apparently retrying every 45 seconds.
 
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Old 01-19-09, 10:17 AM
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Originally Posted by torqueaddict View Post
I performed some tests and found that when the furnace was not working, I was getting 0 VAC at the valve. When it was working, the valve would get 24VAC at about 40 seconds after the heater is turned on. The problem is intermittent. (The heater USUALLY works)

.
Since the ignition control module is not switching the gas valve on reliably, you have a failing ignition module which should be replaced.

It's s safe bet that this will continue to get worse and quit working altogether before too long.
 
  #21  
Old 01-19-09, 10:20 AM
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The overheating of the house is very likely a manifestation of the same problem --- the ignition control module isn't operating reliably. Sometimes it fails to turn the gas valve on, other times it fails to shut it off.

Two fixes for the price of one ---- what a deal!
 
  #22  
Old 01-19-09, 11:47 AM
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thanks for all the help- I will be looking to pick up one of those modules - I see universal ones all over the web for about 100 bucks. I know a little about furnaces now!
 
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Old 01-19-09, 04:49 PM
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Originally Posted by torqueaddict View Post
If I am not getting voltage at the gas valve, does that mean my Ignition Control Module is bad? Or, are other components involved in delivering the 24 VAC needed to activate the valve?
Not necessarily. First you have to make sure when gas valve voltage is lost, it is not a result of any of the 24 volt safety switches failing. And especially when failure is at onset of the sequence, that the pressure switch system (system entails not just the switch, but the entire inducer venting parts and process, and includes the vacuum tube, the ends where it plugs into.....even the condensate line and trap..... that you must make sure the holes are not gooked up not even partially, and that the condensate water is not backing up into the secondary heat exchanger which can lead to the exhaust gas being held back and shutting down the pressure switch, and to see that exhaust vent is not partially blocked outside. Any of this can shut down the pressure switch, which then will not allow the gas valve 24v to come on.

Not that this is your problem. It MAY very well be your module. But check this stuff out, first. And make sure you have 24 volts at the module when/where you shoud have, or 120v line current where/if you should have (for ignition) and that it is grounded good - before condemning the module. And yes, it is not rare for modules to go out. But you always want to check out everything else before spending the $100 for a new one.
 
  #24  
Old 01-20-09, 04:59 AM
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wire to test for safety lockout for 24VAC gas?

I'd like to test that the 24VAC for the gas isn't being prevented due to a safety lockout.

There must be a wire that delivers voltage to the ignition module if there is a safety issue present. Do you know how I can identify that wire?

It was in the 50s again this morning when I woke up (the problem usually happens in the morning - I have the program lower the temp to 63 but it gets much lower) The induction fan was on, no flame, no glowing ignitor, no main blower, no volts at gas) I shut down the heater and turned it back on, all was fine.

thanks in advance for any more help- I am 90% sure it's the ignition module, but I want to test a little more.
 
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Old 01-20-09, 05:29 PM
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If you have a module, post what all the abbreviations are, where the wires are connected to the spade connectors.

With your symptom going on, where the inducer comes on and you get a glow of the HSI, then the click but no fire, until finally the furnace gives up trying to light and "locks out" with just the inducer running constantly, until you shut off the furnace to restart the sequence -

Test the ignitor to see if it is weak.

Test the voltage to the gas valve MV to COM wires, and be sure to reverse your test probes(if you do not get 24 volts AC) and perhaps even disconnect the wires from the gas valve terminals to directly test only the 2 wires stated.

IF you get that current to show up at MV and COM, in those 2 wires, that means current is being sent to the gas valve (which also means all your safeties are working).

But if not, look elsewhere.

But if say it (24 volts at gas valve wires) IS there, yet no fire, then you can suspect either a weak HSI or stuck gas valve. You can find out if the gas valve is stuck or not, (if you get the 24 volt current to MV and COM), by either trying to light off the gas burner with a barbeque lighter near where the HSI is located, or check the gas meter to see if the 1/4 or 1/2 foot dial ever moves when the furnace is trying to light. If it never moves, then no gas flow. If you have current to the valve, but no gas, the vent/regulator may be screwing up somehow or the gas valve is plain shot where it tries to open up at the solenoid, or it is sticky. If it is sticky, sometimes you can free up the valve with some raps on it with something like the plastic handle of a screwdriver, which gives a nice sharp rap, yet not damaging.

But if you are not getting any 24 volts to the 2 gas valve wires mentioned (and as I said, if no reading, try reversing the voltmeter probes, to be sure), no sense rapping on the gas valve, obviously.

If no juice to the gas valve as described above, then test to see if the pressure switch is opening up. Various causes if it is. Even condensate water in the condensate drain tubing can back up into the secondary heat exchanger and cause the pressure switch to sporadically "open" (lose current to outgoing wire) any time during the start up sequence. Or the smaller 1/4 inch looking rubber tubing that comes from the inducer and goes to the pressure switch.....the 1/8 inch hole into the inducer may have gook in it and you can ream that hole out with say a drill bit or coat hanger or something. Blow through tht tubing also. Make sure afterwards that all tubing is reinstalled good and tight on the barbed fittings, and that the tubing or plastic nipples do not have any cracks. The slightest crack can kill the pressure switch. But no sense going thru all this PS testing if you have 24 volts in both the incoming and outgoing wire of the PS when the flame does not come on.

But let us know what you find out with all the things mentioned.
 
  #26  
Old 01-22-09, 03:01 PM
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about to give up and call someone... any last suggestions?

I determined the problem was not the induction fan since there was adequate suction to activate the switch.

I noticed that sometimes the furnace would turn on, then the flame would go out too soon, and other times it would not light at all. I determined the ignitor was ok by holding a long match over the burners during the ignition - no light (tried this several times) I noticed that there was always 24 VAC at the gas valve but when the flame failed to light, the VAC went to 0.

I took an educated guess and replaced the ignitor, and it's doing the same thing.

any final suggestions???? It's looking like the gas valve or some relay but I don't think the gas valve is opened by an external relay.
 
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Old 01-22-09, 03:24 PM
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Originally Posted by torqueaddict View Post
I noticed that there was always 24 VAC at the gas valve but when the flame failed to light, the VAC went to 0.


With no voltage at the gas valve, you are not going to get any gas to burn.

If you are satisfied that the pressure switch is staying closed reliably, then you have a bad ignition control module.


One basic troublshooting theory is to treat a part like the ignition control module as a black box. If all the inputs to the black box are there, it should have a known output. If the known output isn't there, the black box is no good and needs to be replaced.

It sounds like all the inputs to the ignition control are there, and indeed the furnace operates properly sometimes but not reliably. You have found that it's not supplying the voltage needed to open the gas valve and start the burners.

So I conclude that the ignition control module is defective.

Does that make sense to you?
 
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Old 01-22-09, 03:53 PM
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I have a new ignition box...

Hey - thanks for the quick reply!

I thought it was a defective ignition module too - just put a new one in and it acts the same.

Let me rephrase what's happening with the valve.

The ignition sequence is as follows (these ALWAYS happen foe me)
1. induction fan turns on (immediate)
2. ignitor turns on (5 seconds)
3. 24 VAC at valve (40 seconds)

Here's where things go wrong:
4a. SOMETIMES the 24 volts stay on and the flame ignites
4b. SOMETIMES 24 volts are present for about 3 seconds then 0 VAC - never any flame present.


ALSO:
5. Sometimes the flame goes out prematurely. Sometimes after 20 seconds, sometimes in 10 minutes, but the house is still cold, and the ind. fan stays on, etc...

Could it be the valve? It guess depends on how long 24 VAC needs to be there.

I don't know how long 24 VAC needs to be there to ignite. I tried a match but it doesn't help.

Something else is wrong - maybe a gas valve, maybe something else less obvious...
 
  #29  
Old 01-22-09, 04:18 PM
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Has this furnace ran much this heating season?

Has it ran basically good the whole time except for just now?

Have you tried to rap on the gas valve when it should be coming on, say with the plastic end of a screwdriver?

What kind of gas is it? Any other gas appliances in the house?
 
  #30  
Old 01-22-09, 04:22 PM
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multiple natural gas appliances that are operating normally - furnace ran fine up to last 2 weeks - I'm in PA so the furnace got used pretty regularly last month with no issues.

I tried tapping on the valve right when the volts are applied (also looking at my watch)

If it's not obvious I'll call someone - I just like to take a crack at these repairs when they come up - usually I get lucky!

If I end up calling someone I'll post when the real problem was.
 
  #31  
Old 01-25-09, 07:03 AM
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had someone look at it

I was told I should replace the valve and the flame sensor. I put the parts in and it was working ever since.
 
  #32  
Old 01-28-09, 05:02 PM
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York Furnace

Almost the exact same problem on my York. Mine was installed in 1993, but could be a 1992 model.

The technician changed the ingition control unit first...that was a wasted $360 service call. (Part # 50E47-040) Problem continued. (Note he replaced with a universal replacement which was a S8910U)

Ended up being the brown relays under the ignition control unit. If you tap on the relay (with safety switch depressed) our unit would crank up.

The left relay part number is 024-23237, but I could only find the White Rogers suggested replacement part number 90-340. About $10 online.

The right relay part number is R8222B 1059. The R8222B is easy to find, but the 1059 version may be obsolete. Could probably use one of the others. This is a Honeywell relay.

Not sure if it was one or both the relays, but at $10-$15 a piece heck, change 'em both.
 
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