Author Topic: Coleman Echelon CP9C100C16MP11 failing when fan switches speed mode  (Read 358 times)

Offline ucph

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Hello there,

We are having issues with our furnace since we bought the house 2years ago (house is 6 years old)
The tech replaced the board and both pressure switches. We still have issues.
The Furnace starts up fine for about 5min when it wants to modulate the speed instantly the flame stops and 3 red lights. As mentioned, he just replaced the pressure switches.
Than he mentioned that the exhaust pipe might be to small 2”. The length of this pipe is about 10ft and has 4x 45degree joints. He said somehting there should be 3" pipes because od the BTU size. We had different techs here but nobody can fix the furnace.
Does anyone have any idea, Please?
Thanks
Peter

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Re: Coleman Echelon CP9C100C16MP11 failing when fan switches speed mode
« Reply #1 on: January 12, 2019, 08:03:14 AM »
I believe the 100,000 BTU model can use 2” venting up to 30’.  You have about 20’ of equivalent venting and should be fine.

Pull the pressure switch tubing off of the exhaust motor port and look inside with a flashlight.  If you see a water droplet try to enlarge that port with a 3/16” drill bit.  Otherwise replace the exhaust motor.

Did you add air conditioning recently?  If so where does the drain line terminate?

Offline ucph

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Re: Coleman Echelon CP9C100C16MP11 failing when fan switches speed mode
« Reply #2 on: January 12, 2019, 08:33:05 AM »
Thank you for answering so fast.
No, Air Conditioning was installed with the Furnace.

It's strange. This furnace always had problems running smooth. The last technician replaced the pressure switches and it worked to 90%. Somethings 6x red sometimes 3x red.
The board was replaced and it did not change anything. The technician yesterday replaced both pressure switches again and noticed that one switch had a lower vaule as requiered. After he installed the new pressure switches the furnance always turns off when it wants to modulate to the high speed.

No water inside

Peter

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Re: Coleman Echelon CP9C100C16MP11 failing when fan switches speed mode
« Reply #3 on: January 12, 2019, 09:17:57 AM »
Does your furnace have an intake vent attached to the top or side of the furnace?

Read this recent post,

https://www.hvactechgroup.com/hvacforum/index.php?topic=927.msg9000#msg9000

Offline ucph

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Re: Coleman Echelon CP9C100C16MP11 failing when fan switches speed mode
« Reply #4 on: January 12, 2019, 10:23:04 AM »
Intake is on the top.

I past your previous info to the Tech but he said the info is not for Coleman. That was his answer.


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Re: Coleman Echelon CP9C100C16MP11 failing when fan switches speed mode
« Reply #5 on: January 12, 2019, 01:14:21 PM »
Yes, but your furnace allows the intake to be connected to the side of the furnace, instead of the top.  The problem may be similar to what is shown in the bulletin.  When the intake vent is attached to the top of the furnace it's possible for condensation to drip onto the gas valve.

And there are know pressure switch problems with your furnace.  You want to make sure you have the proper pressure switch, not one with a lower rating as that won't help the problem.  Make sure none of the pressure switch tubing has water inside or you may need to look at the drainage system.