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Furnace kicks off & on repeatedly,doens't reach temp. since humidifier install

Furnace kicks off & on repeatedly,doens't reach temp. since humidifier install

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  #1  
Old 02-23-15, 11:45 AM
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Furnace kicks off & on repeatedly,doens't reach temp. since humidifier install

Ever since we had someone install a humidifier, our furnace kicks off and on. sometimes only coming on for a few seconds, shutting off a few seconds, then coming on for a few minutes. This happens 24/7. I first blamed it on the fact that it has been really cold lately and maybe I was just being overly observant since we just had the humidifier installed, but my wife realized that the thermostat is not reaching our set temperature.

Before I call the installer back, I was wondering if you had any insight. I am assuming it has something to do with the humidifier installation, but I guess it could also be coincidental.

What do you think?

Thanks!
 
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  #2  
Old 02-23-15, 12:08 PM
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Could be a heat anticipator issue if you have an old mercury thermostat.

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  #3  
Old 02-23-15, 12:37 PM
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Good idea, but we have a programmable thermostat that I installed about 3 years ago.
 
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Old 02-23-15, 01:38 PM
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Any LED codes displayed at the furnace?
 
  #5  
Old 02-23-15, 01:51 PM
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A heat anticipator issue won't cause cycling every few seconds.

You might have a weak transformer that's just overloaded with the humidifier on there. Best thing to do is disconnect the electrical part of the humidifier and see if it works properly.
 
  #6  
Old 02-24-15, 11:52 AM
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Thought I would post an update.

Thank you everyone for your ideas, I appreciate it.

I don't see any "LED codes" on the furnace, I don't think ours has that ability.

I disconnected the humidifier wires from the panel in the furnace. This did not resolve the problem.

I removed the "Flame Sensor" and cleaned it up w/ some 180 grit sand paper. This did not resolve the problem.

Any other thoughts? Thanks!
 
  #7  
Old 02-24-15, 12:30 PM
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Could be the hi limit switch is tripping. Make sure you have a clean filter.
 
  #8  
Old 02-24-15, 12:48 PM
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Can't tell what's going on without being there - might need to call a tech.

Post entire sequence of operation - startup and exactly what happens when it cuts out. There should be a flashing led.

Check all electrical connections.
 
  #9  
Old 02-24-15, 06:13 PM
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Here is another update.

- Changed the filter, problem not fixed.

- I found the LED light on the Control Board that was mentioned previously, I watched it through the peep hole for multiple cycles and it never lit up.


York, Model P3URD20N9501A
The Control Board is a White Rodgers, Model 50A50-241

I tracked it's cycle tonight, we let the temp drop to 62 and then set the thermostat on 67, here are the results:

7:15 ON @ 62
7:17 OFF @ 62
7:17 ON @ 62
7:18 OFF @ 63
7:19 ON @ 63
7:22 OFF @ 64
7:23 ON @ 64
7:24 OFF @ 63
7:25 ON @ 63
7:26 OFF @ 63
7:26 ON
7:27 OFF
7:27 ON
7:28 OFF
7:28 ON
7:30 ON @ 63
7:32 OFF @ 63
 
  #10  
Old 02-25-15, 06:12 AM
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I did some more investigating last night. Here are the updates

- changed the filter, problem still exists.

- I found the LED light referenced previously. I watched it through a few cycles and it never lit up.

I monitored the ON/OFF cycles and here is a synopsis. We let the temp fall to 62, then set the thermostat on 67. It literally came off and on about every 1-2 minutes, never reaching 67. After 20 minutes, it had got up to 64.

I guess I'm going to have to call the company that installed the humidifier.

Thanks for all your replies.

I'll keep you posted.
 
  #11  
Old 02-25-15, 09:54 AM
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I would jumper R to W at the furnace to eliminate the stat as the cause.

R = 24vac
W= heat
G = fan
Y = compressor
C = common
 
  #12  
Old 02-25-15, 12:21 PM
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Thanks for the suggestion about the R/W wires.

Here is another update.

I called the guy who installed the humidifier. Here are the results of today's tests.

- Took off the face of the digital thermostat, hooked up a jumper wire between R & W, furnace still cycled every minute or so. Took off the jumper, just to make sure I was doing things properly, and furnace didn't come on. Thus, eliminating the thermostat as the problem. :-(

- Check the exhaust pipes that go outside, no obstructions.

- the HVAC guy told me that sometimes, when using sandpaper on the flame sensor, it can make the surface too rough. He told me to try steel wool to smooth it back out. Tried, still has the issue.

Going to call the HVAC guy back later to see if he can come out this week. :-(
 
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