Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 12-15-2013, 08:16 PM   #1
Another DIY Zombie
 
Join Date: Jun 2008
Location: Champlain, NY (NY, VT, QC Border)
Posts: 281
Share |
Default

2008 York Modulation Furnace PM9C Issues


I have had this furnace since new in 2008 (fall). I admit that the install was done by myself as my father-in-law (contractor) purchased it for me. We sized it based on the house size etc (I used to do HVAC design), and feel very comfortable with the install, which was very easy. The furnace ran fine for the first year, then I started to get the "3-Red Flashes" error, indicating a stuck open pressure switch, among other things. The main issue I have is that when this occurs, I no longer have a flame and the house gets cold. I have seen the temp go from 70 down to the low 60's as the furnace fan will keep running even though there is no flame.

I am trying to source a local contractor to dig into this and see what we can do about it. the problem I have is the lack of flame. Why is it that this thing does not simply shutdown when the flame is gone? It just stays running at 100% without stopping, all the while, blowing cold air through the house.

One thing I have tried is to run the furnace at a lower speed via the Test mode and this works. I am curious if the root of the problem is at the condensate trap as well. I have recently cleaned this out with hot water and found lots of slimy buildup.

Any thoughts / opinions are appreciated!

javan is offline   Reply With Quote
Old 12-15-2013, 09:29 PM   #2
AKA HVACTECHFW
 
Join Date: Nov 2010
Location: NE Indiana
Posts: 2,318
Blog Entries: 1
Default

2008 York Modulation Furnace PM9C Issues


Ensure the intake and exhaust pipes are clear. The unit reacts as it is programmed to do when the control board observes a fault. The pressure switch is used to indicate that the system is venting properly. A plugged condensate trap will also cause pressure switch issues. You should also ensure proper slope of the flue pipes.

__________________
IT IS WHAT IT IS
hvactech126 is offline   Reply With Quote
The Following 2 Users Say Thank You to hvactech126 For This Useful Post:
ben's plumbing (12-16-2013), carmon (12-15-2013)
Old 12-16-2013, 07:44 AM   #3
Another DIY Zombie
 
Join Date: Jun 2008
Location: Champlain, NY (NY, VT, QC Border)
Posts: 281
Default

2008 York Modulation Furnace PM9C Issues


Well, the intake and flue are both clear. The flue is pitched correctly. The drain lines to the trap are all pitched correctly.

I guess for me the real troubling part is that when the flame is lost, the fan keeps running. To me that is a design flaw.....

Last night I had the furnace in test mode set to run at 35%, which it did flawlessly until this morning. Not sure why, but once the Tstat told it to jump from the 67 deg setpoint up to 70, it started right off cold. Again the error was the stuck pressure switch. I have been in contact with others who have had the same issue and simply keep replacing the pressure switches, but that only seems to buy them a short fix. I have done that 4 times now it only lasts for a month at most.
javan is offline   Reply With Quote
Old 12-16-2013, 08:56 AM   #4
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 9,256
Default

2008 York Modulation Furnace PM9C Issues


Post a well lit closeup pic of the pressure switch and the tubing from it to the collector box. I don't see a lot of Yorks but on some brands that tubing if it is in the shape of a loop can trap water in it and then cause nuisance tripping. May need altering but I need to see it. Check the port on the collector box where it attaches for blockage.
__________________
"Cut it twice and it is still too short".
yuri is offline   Reply With Quote
Old 12-16-2013, 09:17 AM   #5
AKA HVACTECHFW
 
Join Date: Nov 2010
Location: NE Indiana
Posts: 2,318
Blog Entries: 1
Default

2008 York Modulation Furnace PM9C Issues


Almost all furnaces react that way when a fault condition is found by the control board. That's not a design flaw.
__________________
IT IS WHAT IT IS

Last edited by hvactech126; 12-16-2013 at 03:55 PM.
hvactech126 is offline   Reply With Quote
The Following User Says Thank You to hvactech126 For This Useful Post:
ben's plumbing (12-16-2013)
Old 12-16-2013, 02:10 PM   #6
Another DIY Zombie
 
Join Date: Jun 2008
Location: Champlain, NY (NY, VT, QC Border)
Posts: 281
Default

2008 York Modulation Furnace PM9C Issues


I will send a pic later tonight.

As for the tubing arrangement, etc. I did have to made a few mods (shorten some) as there a couple that would trap water. Again, this was fine the first year. I did not mod the tubing until the 2nd and 3rd year.
javan is offline   Reply With Quote
Old 12-16-2013, 04:52 PM   #7
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,778
Default

2008 York Modulation Furnace PM9C Issues


Check that the furnace trap is not cracked.

Problem may actually be in the board. Some of them had to be replaced to stop nuisance trips.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is offline   Reply With Quote
The Following 2 Users Say Thank You to beenthere For This Useful Post:
ben's plumbing (12-16-2013), hvactech126 (12-16-2013)
Old 12-16-2013, 05:24 PM   #8
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 9,256
Default

2008 York Modulation Furnace PM9C Issues


Lennox used to have that issue with some of their traps. If they get a hairline crack then they can get airlocked and won't drain fast enough and sometimes trip the pressure switch. Mod furnaces are VERY finicky and sensitive to that.
__________________
"Cut it twice and it is still too short".
yuri is offline   Reply With Quote
The Following 2 Users Say Thank You to yuri For This Useful Post:
ben's plumbing (12-16-2013), hvactech126 (12-16-2013)
Old 12-16-2013, 07:58 PM   #9
Another DIY Zombie
 
Join Date: Jun 2008
Location: Champlain, NY (NY, VT, QC Border)
Posts: 281
Default

2008 York Modulation Furnace PM9C Issues


Here are a few pics of the pressure switch and drain lines Not the greatest as the lighting is not the best.....

I have read about the trap being an issue at times, and think that I have to be more aware of that, and perhaps make it a monthly maint item. Although I do not believe that it should be that way.

Regarding the comment about all furnaces operating such that if they lose flame, the fan keeps running, I still feel that it is a very poor process. I mean, a good example is next week I will be away for 2 weeks. If I lose the flame on day one, I could potentially come home to a house with broken pipes.....

I think the better sequence would be that you lose flame, the unit shutsdown and restarts. I found that my furnace seems so much nicer when running at minimal capacity anyway (quieter, less chance of losing flame...). Instead, it starts off nice ans slow and peaceful, runs for about 10-15 minutes this way, then speeds up and runs another 10-15 minutes, then finally runs for another 10-15 minutes at the high fire rate that sounds like a plane!
Attached Thumbnails
2008 York Modulation Furnace PM9C Issues-2013-12-16-17.31.39a.jpg   2008 York Modulation Furnace PM9C Issues-2013-12-16-17.32.13a.jpg   2008 York Modulation Furnace PM9C Issues-2013-12-16-17.30.47a.jpg  
javan is offline   Reply With Quote
Old 12-16-2013, 08:34 PM   #10
AKA HVACTECHFW
 
Join Date: Nov 2010
Location: NE Indiana
Posts: 2,318
Blog Entries: 1
Default

2008 York Modulation Furnace PM9C Issues


FYI, your flex gas connector should NEVER be run through the furnace cabinet. Especially without a grommet and while laying on the sharp sheet metal cut-out.
__________________
IT IS WHAT IT IS
hvactech126 is offline   Reply With Quote
The Following User Says Thank You to hvactech126 For This Useful Post:
yuri (12-16-2013)
Old 12-16-2013, 10:30 PM   #11
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 9,256
Default

2008 York Modulation Furnace PM9C Issues


That gas connector looks very dangerous and they are not that thick and it could get damaged and leak from vibration. Totally illegal where I am. Must be completely outside the furnace and in a straight line. The hoses look OK but I cannot see where they go at the bottom of the left side of the pic. Looks like water will flow back to the ventor fan and not get trapped. I don't know why York runs the fan that way. All the furnaces I see when they trip a pressure switch they recycle/try restart 3 times and then shut down completely for 3 hours and then try again/autoreset.
__________________
"Cut it twice and it is still too short".
yuri is offline   Reply With Quote
The Following 2 Users Say Thank You to yuri For This Useful Post:
carmon (12-17-2013), hvactech126 (12-16-2013)
Old 12-17-2013, 04:13 AM   #12
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,778
Default

2008 York Modulation Furnace PM9C Issues


What sounds like an air plane, the burners, or the air flow.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is offline   Reply With Quote
The Following User Says Thank You to beenthere For This Useful Post:
hvactech126 (12-17-2013)
Old 12-17-2013, 08:40 AM   #13
Another DIY Zombie
 
Join Date: Jun 2008
Location: Champlain, NY (NY, VT, QC Border)
Posts: 281
Default

2008 York Modulation Furnace PM9C Issues


So, the gas line is a bad deal and I will get that fixed asap! I guess it has been that way for so long I am used to seeing....

The Plane sound is the fan. Last night was a good example. Very cold here in Northern NY (bottomed out around -15 for me). Anyway I awoke at 1:30 and heard the unit running, very quiet, just whispering away. I got up and checked the temp at the supply grille. Barely over ambient. I went to the basement and checked it out, Good flame, but running on min. I left it, thinking that the furnace must have just come on. I went back upstairs and checked the tstat. Set at 67, current temp was 63. I went back and shut off the furnace and restarted it. Came right on, nice flame, quiet at min flow, I went back to bed and listened to it for about 20 minutes at the minimum rate, then I could hear the unit increase in fan speed to maximum very quickly. I went back and checked and sure enough, 3-red flashes. I reset the unit once again and this time it went about 15 minutes at low, then increased in speed and fire for another 15 minutes before jumping up to full very fast. Again back to the basement, again 3-red flashes. I reset it again at about 4am and it ran fine, went through 2 cycles that I know of and maintained the setpoint. Was working fine when I left for work.

I cleaned out the condensate trap on Saturday, thinking it may be clogged. It was not clogged. The pics do not really show everything that clearly, but all condensate drains are pitched towards the trap. One thing that I did not take a pic of was the trap itself. I will tonight. I know that the tubing out of the trap has a sharp 90 deg. bend to run out of the furnace into the PVC drain (vented) to the sump.

As for the unit possibly resetting itself... We were on vacation over Thanksgiving and had a friend popping in daily to check on the pets. He left a message on Thanksgiving day that the furnace was blowing cold air and was loud but he did not touch anything. When we got home Friday night the house was warm and at setpoint. So, perhaps it does cycle and reset, but why must it automatically jump to 100% fan when it loses flame? That just takes the house temp down so quickly!
javan is offline   Reply With Quote
Old 12-17-2013, 09:24 AM   #14
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 9,256
Default

2008 York Modulation Furnace PM9C Issues


Beenthere is a York dealer and he said the board may be the problem. I would be tempted to replace it. If the old one still works and the board is not the problem then it is still good for a spare and has value. also jack up the back of the furnace about 1/2 an inch so the water flows out of the secondary heat exchanger faster. had a few Lennox that were finicky that way. most install manuals recommend sloping the furnace forward anyway. Kinda sounds like the board is not modulating properly. You should always get at least a 40-50 deg temp rise and not air coming out at ambient like you said. the board should slow down the fan to adjust to the lower firing rate if it has an ECM motor. it should also be setup for a proper temp rise at high fire and not sound like a rocket. I don't see many Yorks so I cannot tell you how but it should be in the install and startup info.
__________________
"Cut it twice and it is still too short".

Last edited by yuri; 12-17-2013 at 09:52 AM.
yuri is offline   Reply With Quote
Old 12-17-2013, 06:11 PM   #15
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,778
Default

2008 York Modulation Furnace PM9C Issues


Remove the pressure switch and see if it has moisture/water in it.

Is it piped as a single or 2 pipe system. If 2 pipe, are both pipes terminated at the same place out side.

Post a pic of your control board.

If you have a digital thermostat is your thermostat set to 3 or 6 CPH.

__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Seeking help with Furnace Issues atdwest HVAC 7 11-27-2013 05:03 PM
York furnace problem brucem609 HVAC 7 11-03-2013 06:35 PM
Brand New Concord Furnace Doesn't Work In Cold Weather LeighC HVAC 21 01-07-2013 08:48 PM
York vs Rheem furnace venting raylo32 HVAC 6 08-30-2011 04:28 PM
York Furnace Leaking.. Please help sidoe HVAC 4 10-08-2007 04:55 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.