2004 Maytag Furnance runs then stops

When the thermostate for the morning goes to 68 (from 60), the furnance kicks on and runs about 1 hour. Then it stops, even though the thermostate temp is below 68.
It goes into this cycle:
-- big blower fan runs slowly
then.. -- a small blower kicks on for about 25 seconds -- the ignition element begins to glow for about 15 seconds -- 3 of the 5 burners ignite for about 5 seconds -- the elements stops glowing -- the burners go out -- the small blower stops after about 15 seconds repeat the above
When it started up the last two mornings, it did run for an hour before we went into this start/stop routine.
I'm looking for hints/tips before I call any repair shop.
Regards,
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kansascats wrote:

Hi, How is the filter? Is it clean? Running time is not an issue, not reaching the set temp. is. Can you read diagnostic code?
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Filter appears dirty -- I will replace. There is decent airflow though.
I see 2 lights -- one is labeled "flame" the other I cannot quite make- out yet. The other is red or flashes red. I will take a closer look.
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FWIW I have 4 wires to the thermostat --- two doorbell-type wires -- total of 4 wires. They were attached to
R G Y W
I changed out the programmable thermostat -- no real change.
It did again run for 15 or so minutes and then stopped.
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I'm looking for hints/tips before I call any repair shop.
Regards,
----------------------
Sounds like a dirty flame sensor. Mine needs cleaning every two years. The shut down and start-up procedures follow your problems exactley.
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But why does it run for an hour each morning and then start acting flaky?
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"hr(bob) snipped-for-privacy@att.net" wrote in message wrote:

But why does it run for an hour each morning and then start acting flaky?
-------------
Well we keep our house with a temp range like the OP. Our home time temp is 73 or 74 and our nighttime temp is 67. Because the furnace doesn't work as hard at night, we were told the flame sensor (it's some space age rod material) is cooled down and allows the firnance to run about 30 or 40 minutes before shut down on the first morning run.
The furnace turns on and off more frequently when it tries to keep our home at 74 and that's where we get these 2 minute fire up and shut down cycles. The tech is usually called out every other march or April, wipes the rod down and we are good to go. ours is a 13 year old Coleman and they are famous for this problem. I have a feeling the air the flame uses is getting dust from my workroom beside it upon fire-up and it burns that dust and it dirties up the rod.
It's just an Idea for the OP to consider.
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On Sun, 20 Mar 2011 08:01:17 -0700 (PDT), kansascats

What kind of furnace is it? What does it burn?
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On Mar 20, 5:43pm, "Stormin Mormon"

Agree. If some of the burners aren't lit, while the others light but go out in a few seconds, it has nothing to do with a dirty filter or the thermostat. Something is preventing it from firing correctly and the safety checks are shutting it down.

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As I recall.. 3 burners fire at first.. and then after an extended runtime (how much I don't know), the other two come on. The theory is that it may only take 3 to get the house to the desired temp --- and then the others come of a bit later.
There is some black box -- about 1.5" square that has a dial on it that says something about delay time.
It's a Maytag -- natural gas.
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How do I find a "good" service company?
Someone with Maytag knowledge.
The folks I had install -- not impressed.
I'm in the northern CO front range area -- Boulder/Loveland.
Thanks much.
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That may be possible if it's a two stage furnace. Not sure how they all operate, but mine fires all burners whether at first stage or second. For the lower firing rate the gas valve just reduces the pressure. Seems like the best approach to me, as it uses all the heat exchanger, which I would think would lead to a little better efficiency. But there may be some furnaces that do it by using less burners.
You may be able to find a manual for the actual furnace online that describes how it operates. But, you are dealing with gas, so unless you are experienced and know what you're doing, I'd recommend getting a pro in.
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OK -- found the install/user manuals, wiring diags.
-- it's 2 stage with a timer (the time was set to 2 mins or so, I moved it out to 5 fwiw) -- there is a primary valve that feeds 3 burners and a secondary one for the other 2
This AM it did the same thing -- came on -- ran for about an hour, got the house nearly to desired temp then stopped. The yellow - flame sensor - light flashes, then shuts off. After it retried serveral times, and stopped, the red light flashed 4 times (ignition failure). Later on -- it came on and worked just fine. So it's itermittent, but seems to be the flame sensor. Visually, the flame looks good -- blue with a touch of yellow at the ends.
Any tips for cleaning the sensor? One screw and I can remove.
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On Mon, 21 Mar 2011 09:19:46 -0700 (PDT), kansascats

Fine steel wool. Don't overdo it. Takes barely any cleaning in my experience.
--Vic
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I used a scotch bright pad -- polished 'er up and put it back in -- 5 min job.
It fired right up and seems good -- tomorrow AM will be the pudding...
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"kansascats" wrote in message
I used a scotch bright pad -- polished 'er up and put it back in -- 5 min job.
It fired right up and seems good -- tomorrow AM will be the pudding...
-----------------
Told ya. :) Finally for once I'm able to help somebody instead of them helping me.
The one reason I don't clean my own is they are fragile on mine and a replacement one is about $110 CDN. I should just suck it up and clean it anyways.
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If he gets it straightened out, I'd also suggest considering wiring it up as a true two stage furnace. That requires a two stage thermostat and one additional wire. Then the thermostat, which has the necessary info, can decide whether to fire it at first stage or 2nd.
The way it was set, ie to fire at 1st stage for 2 mins, then go to 2nd is just dumb. But it shows how dumb some furnace manufacturers are. Do they really think that furnace could raise the temp enough in 2 mins so that the thermostat would shut off? All they are doing is denying you 2 mins of full heat every time the furnace starts. I've seen other furnaces that offers settings of 7 or 10 mins, which at least is reasonable.
But to get the best performance, you need it wired to a two stage thermostat. Then if the thermostat just kicks on by itself, it will do it in first stage. On the other hand, if it's in recovery mode after being setback at night, it will immediately go to 2nd stage. Or, if you move the thermostat up a couple degrees, it will immediately go to 2nd stage.
The timed option is for either situations where it either the extra wire is not available, or the installer is lazy/cheap.
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This AM went well -- heated up to 68, then held it there all day. It was a warmer evening, so it did not have to run more than about 40m to reach desired. I noticed the flame sensor is now solid yellow (on) vs flashing. This eve I bumped it up to 69. It went there, and then fired on/off a few more times to keep it there.
The timer has a setting for 1 min to 8. I set it to 5 now. It was 1 or 2.
The wiring diags show with a 2 stage thermostat, timer, low only, high only, and some other option I believe.
I was not impressed with my installer. The first time around the installed AC. A hack job. When I went to install the furnace, they tossed in an extra day labor to better my supply and return lines. Even then, I have my doubts they did anything but just plug it in. The install guide talks about taking measurments and making settings. I'm certain that was not done. They even mentioned it was a 2 stage -- but failed to discuss the need for a 2 -state thermostat.
On another topic -- my registers are those 2" x 10". I get much better performance if I pull the register covers off. Seems most newer homes now have the 4" x 10" registers. The covers seem to cut flow significantly.
Tonight should cool off more -- so tomorrow should be a better test.
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Sounds like you found the problem.

One would think that other option would be true two stage operation. In which case you need an additional wire from the W2 terminal on the furnace to the W2 terminal on the themostat.
The way it was settup, with the timed 1 min option, it was essentially a single stage at high output, starting on low for 1 min, then running on high the rest of the time.

The most important measurement is the temp rise, where you measure the incoming return air at the furnace and the hot air leaving. It has to be within a certain range which should be specified on a sticker inside the furnace and/or in the install manual. Depending on the type of blower, you may be able to speed up or slow down the blower slightly to get it into the range, or center it in the range, etc.
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wrote:

I agree about the thermostat, waste to not have a 2 stage one.
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