Westinghouse furnace issue

joe8918 · 11-30-2011, 10:32 AM

Hello - I'm new to this forum and think that I might be able to get help to determine the issue I've been experiencing.

I have a four year old 95.1% efficiency Westinghouse furnace (2-stage) model #FG6TE-100C-VB (FDG061005877). I have experienced intermittent (about once a week) issues where there is a fault which gives a code of 2 flashes which means "Pressure Switch is open with inducer on". I have removed the rubber tubes which connect the inducer motor to the pressure switches (it actually goes to 2 of pressure switches of this furnace) and ensured that I could blow through these tubes (after disconnecting them from the actual pressure switch as I know you can damage the component). I have removed all of the tubes which are not even connected to the motor to ensure no blocked passages. I then lightly sucked on the tube connected to ensure that I hear the light "click" in the switch.

I have never been left "dead in the water" with the issue but I'm just trying to quit having to worry about if the furnace will start clicking and show this fault. I called a service tech and he came out and just did the exact same things I did, restarted the furance and recorded it as no issue. This has been happening since last heating season. Does anyone know what else I can check to identify what the true issue is? I know it could definately be the actual sensor but I know that I don't want to just start throwing parts at the issue. I thought that the service tech might have some diagnostic tool but he said there was no such thing ???

sorry it's lengthy but just wanted to provide enough info.

Thanks,
Joe

harleyrider · 11-30-2011, 10:45 AM

You had the wrong guy out Joe, the right guy would have hooked up a magnihelic or digital manometer and read the amount of draft being created by the inducer motor. See the pressure switches have rating on them, and those rating tell us experienced techs what the switch needs to close and stay closed. Since your problem is intermittent, I suspect that it may be a drain issue, such as a dirty condensate trap, and or tube leading to the trap. It is completely possible that its a intake issue as well.......the digital manometer will tell the tech were to look. i have 30+ years in this field Joe, and one thing I can tell you is that pressure switches rarely just quit working.....

joe8918 · 11-30-2011, 07:02 PM

Thanks for your prompt response and input. How do I check the condensate items? I believe your referring to the clear tube that runs from the inducer motor down to a big black plastic box and them out to my condensate pump. Please let me know I need to point out any further system details.

Thanks!

yuri · 11-30-2011, 07:08 PM

did you check the intake and exhaust pipes for blockage? some units also have a screen where the intake pipe attaches to the burner box and it can get plugged with leaves or debris. pressure switches do occasionally fail from vibration if mounted on the ventor fan like some Carriers and the Lennox G61 but it is less than 5% of the problem. mostly blocked intake pipes. have had bags, leaves, wasps nest get sucked in. kids drop golf balls and toys in them also.

ben's plumbing · 11-30-2011, 07:12 PM

hey joe i agree with harley one more suggestion trace tube from pressure switch back to inducer motor remove hose and clean this little port on inducer motor.. sometimes they clog up alittle causing your same issues???

joe8918 · 11-30-2011, 07:25 PM

Yuri - how can I access this possible screen. I haven't investigated this yet. I believe the 3" intake is solvent welded so I can't just lift it off. I'll have to just look at it. Any hints appreciated.

yuri · 11-30-2011, 07:32 PM

we don't have your brand where I am but in general some brands have that screen and it can be tricky to find. check where the pipe attaches to the furnace or remove the cover from the burner box and look inside where that pipe attaches. no easy way to check for blockages. I remove the pipe and blow backwards with a shop vac leaf blower attachment and sometimes that unclogs them or else you have to chop it into pieces and hunt for the blockage. B4 I start chopping I would want to check the draft with a differential manometer and hopefully the "WC rating is stamped on the pressure switch. otherwise you have to get that info from the manufacturer.

condensate/water not draining fast enough or properly could be the problem also although that is usually not an intermittent problem. sucked in bag/wasps nest/faulty press switch usually give you those intermittent problems as the debris can float around inside and sometimes plug the pipe and other times release and let full flow.

hvac122 · 11-30-2011, 08:22 PM

What size is the intake and exhaust pipes? Modems had some of those 95's that required 3" and were very strict on lengths. If not vented properly they would cause intermittent lockouts.

joe8918 · 11-30-2011, 09:42 PM

It has both 3" inlet and exhaust. The run is not long (< 15')

joe8918 · 12-04-2011, 06:50 PM

As an update, I have yet to experience any faults with my system for about a week (which is normal as it only has a hiccup every week or so). Per suggestions I have done the following:
1) removed tube from inducer motor to pressure switch and insert wire to ensure no blockages, etc.
2) inspected drain tube from top of inducer motor outlet nipple to condensation drain tank and emptied water to ensure no blockage.
3) I have identified the box which encompasses the intake as some have suggested I check and see of there is any stuff stuck on a metal grate or something to ensure there are no leaves, bees, etc. stuck in there. I see there are 6 screws holding a plate on that box area but I'm not sure if I should go at it.

Any other suggestions or insight on this?

Thanks for the responses so far.

Joe