Armstrong HE gas furnace problems


  #1  
Old 12-07-15, 08:54 AM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
Question Armstrong HE gas furnace problems

I have an Armstrong HE A93UH gas furnace installed in August 2013 and it had intermittent problems starting the 1st winter(it was fine until then); the inducer came on and tried/hummed for a while then shut off. Not sure if it's related; the 1st time it happened was when I turned up the temp on the thermostat deviating from the programmed schedule. I called in a technician who noticed a 3-flash diagnostic code, denoting 'Pressure Switch Open with Inducer On'. It was fine afterwards though he didn't really do anything so I just left it (he recommended replacing the Pressure Switch since that's what the code was suggesting but after lots of hours online, I now understand most of the times it rather implies non-pressure switch related issues).

Fast forward to 2015 winter/now, the 3-flash code is coming back and even more persistently. The same drill really - when heat is called, inducer fan comes on and after 20 secs or so, everything shuts off. After a while it escalates to 6 flashes, i.e. 'Pressure Switch Cycle Lockout' error code. Shutting off power to the furnace for a while makes the issue go away for a few hours before it returns, and other times not like now

After countless hours on the Internet and without even basic knowledge of how a furnace works, I'm now inclined to believe the issue is caused by excessive water inside the Cold End Header Box (same as more commonly referred Connector box?). There's very little information on this device or the same furnace setup as mine (with 1 Red and 1 Black square tubing connecting the Pressure Switch to the black Cold End Header box and no direct tubing between the inducer and the Pressure Switch. Please see pics).

Name:  Inside - Upper.jpg
Views: 7724
Size:  49.2 KB
Name:  Upper.jpg
Views: 5029
Size:  46.4 KB

I called in a few techs and none could figure out what's going on or resolve this other than a temporary fix, and would really appreciate any light on this, especially what would make a furnace work intermittently. Some specifics/questions/thoughts:

1. The 'Pressure Switch' error code is intermittent so does this rule out the pressure switch itself is faulty?

2. This problem happens in winter time only; yes just when heating is essential.

3. Resetting (turning thermostat/furnace power supply off for a while then on) helps sometimes though not all the time. I'm not sure what 'good' some downtime like this helps in this case. I didn't notice extra water discharging when the system is off.

4. The main reason leading me to believe it's a condensation/water issue is that after turning off the furnace humidifier, it operated normally for longer, close to 24 hours, before failing again.

5. There is water coming out of the main drain pipe when furnaces are on though not much. Also the other furnace is working well, which should indicate the main drain is working? Also I poured some water in the opening of the U trap and water came out relatively smoothly.
Name:  Drain.jpg
Views: 4681
Size:  30.0 KB

6. The 2 furnaces are identical but set up somewhat differently, the left/failing one has the drain pipe on the right vs. the right/normal one on the right, connected to the Collector box drain ports but on the opposite sides. According to Section [0025] in European Patent EP 2354706 at lens.org (this doc depicts exactly the same setup as mine but I'm not allowed to post links here sorry), either the left or right drain port can be configured to work. But in my case, for some reason the left drain port as set up in the failing furnace is not working(?).

7. Not sure if this is related but the failing furnace on the left is tilted to the right(the narrowing gap going up between the furnace and the square duct tunnel), away from the left-side drain, as per the side-by-side pic; would this be potentially causing poor drainage?
Name:  Left Failing.jpg
Views: 2740
Size:  34.1 KBName:  Level.jpg
Views: 2553
Size:  22.1 KBName:  Outside Exhaust II.jpg
Views: 2282
Size:  24.9 KB

8. I pulled out the long black tube from inducer to collector box and the red/- square tubing, and both clear of any blockage. Other tubes are fitted quite tight so I left them alone.

9. Is there a way to tell if water is pooling in the Cold End Head box?

10. One technician released some water from the furnace but I'm not sure what he did exactly as he asked me to fetch some paper towels and he was all done when I returned so I didn't see what he did. Based on the timing, it was a quick easy procedure. Any ideas on this?

11. At my wit end here, I also suspect some clogging in the drain pipe between the Collector box drain port and the trap...

Update: The turning thermostat/furnace power on/off 'resetting' technique is no longer working. What would be causing deteriorating symptoms like this?

Any help is greatly appreciated!
 
  #2  
Old 12-07-15, 01:23 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,499
Received 1 Vote on 1 Post
Whenever the thermostat is calling for heat, the inducer motor should turn on and stay on until that call for heat has terminated.

With a call for heat, the inducer motor should start up and create a negative pressure which is detected by the pressure switch. If that negative pressure fails to develop, you get the 3 flash diagnostic code.

So. You are getting the three flash diagnostic code BECAUSE the inducer motor isn't starting and operating reliably.

You need to verify that the thermostat is calling for heat when you think it is. Use an AC voltmeter to verify that the thermostat is switch on 24 VAC to the W terminal, which is what should happen whenever the thermostat is calling for heat.

If you verify that this 24 VAC is steady at the W terminal and the inducer motor isn't then you need to check to see whether the problem is with the circuit board or the inducer motor.

With the thermostat calling for heat, measure the voltage being applied to the inducer motor. If you have 120 VAC to the inducer motor and the motor isn't coming up to speed and staying on, you have a problem with the inducer motor.

If you have no 120 VAC or intermittent voltage supplied to the inducer motor, then you have a bad circuit board. When you have 24 VAC to the W terminal, the circuit board should switch on the 120 VAC to operate the inducer motor. If it's not doing that, you have a bad board that needs to be replaced.
 
  #3  
Old 12-07-15, 02:02 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
Thanks SeattlePioneer. I think I understand your elimination principle of diagnosis but have never worked on furnaces before so I"m pretty 'clumsy' and not really confident of unplugging cables to check voltages while the furnace is running. Is there any step by step guide/vid? Now I think about it, the inducer motor noise seems not as loud as the other one operating normally but I will confirm when I get home later.

Also is it possible to rule out water in the collector box/inducer based on symptoms by the way? I am thinking of getting a shop vac to suck it out and see if it makes a difference; this is less techy and something I am more confident of doing.
 
  #4  
Old 12-07-15, 02:26 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,026
Received 2,943 Votes on 2,656 Posts
You should be able to safely check the draft inducer voltage (120vac) right at the connection plug.... quite likely without even unplugging it. All the hoses indicated in blue need to be clear.

Name:  Inside - Upper.jpg
Views: 2199
Size:  40.2 KB
 
  #5  
Old 12-07-15, 03:56 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
Thanks PJmax. I will check all the hoses tonight. Will look into checking inducer connection voltage too. Appreciate the pic markers!
 
  #6  
Old 12-07-15, 04:38 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
The 'AC Voltmeter' doesn't appear widely available in hardware stores. Will this work?
AC Voltage Meter - Direcsource Ltd JL-010204-01 - Voltage Monitors - Camping World
 
  #7  
Old 12-07-15, 07:26 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,026
Received 2,943 Votes on 2,656 Posts
You need a multimeter. Not an AC voltmeter. A multimeter can check for AC and DC voltages as well as resistance.

When you call and check.... just ask for an analog multimeter. Most, if not all, hardware stores will have one type or another.

A basic analog multimeter from the Depot. This one is around $15.00. It'll be higher at your hardware store.
Name:  56e1ce39-1603-43f2-b6f1-a6405b3f5696_1000.jpg
Views: 1876
Size:  27.9 KB
 
  #8  
Old 12-07-15, 10:02 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
Thanks for the details on the analog multimeter; will pick one up.

I just checked the 3 hoses; all clear. I didn't pull out the bottom end of the long black hose fitted to the collector box though; it has some kinda stuffer about 1" long inside the tube ('restrictor'?) The top end is clear and I traced down the tube using my fingers and it felt all good. Do I need to pull out the bottom end? Maybe this is nothing but I felt some differences between the 2 'restrictors'; the one in the bad furnace felt slightly more loose and 'grainy' vs. more 'together' and tighter in the good one.

Also I've been contemplating sucking out water and what not through the auxiliary opening of the trap (so I don't need to take apart the trap; I'm concerned I won't be able to put it back together water-proof) just to make sure no clogging or excessive water in play here. Will this be a good idea?

Thanks!
 

Last edited by armstronghelp; 12-07-15 at 11:37 PM.
  #9  
Old 12-08-15, 12:38 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,499
Received 1 Vote on 1 Post
>



I suppose I should call the needed instrument a multimeter, which might prove less confusing.

A multimeter commonly measures AC and DC voltages and current and resistance, and often other things as well.


I've used the term AC voltmeter since it describes the function you need to check voltages in furnaces. But I suppose multimeter is a somewhat more vague term that people would actually find less confusing.

So I guess I'll use multimeter in the future, or at least mention a multimeter as a way of measuring AC voltages.

Sorry for contributing to confusion rather than clarity.
 
  #10  
Old 12-08-15, 05:22 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
No prob at all SeattlePioneer. Only if I were not such a newbie in this.
 
  #11  
Old 12-08-15, 07:47 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
I bought a multimeter but cannot find any step by step instructions or vids on how to test voltages in a setup same as mine per pics, e.g. red and black square hose linking pressure switch and collector box and no hose directly between inducer and pressure switch. Thanks in advance.
 
  #12  
Old 12-08-15, 09:50 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
By the way, I got the gas company tech in almost 2 years ago now; was the same error code. His report read something like faulty pressure switch because 'bypassed the switch and it ran full cycle'. knowing what I know now, pressure switch to me is a safety switch. A tripped switch may indicate something else is wrong like a clogged vent or drain pipe. Bypassing the switch may get the furnace going but with the underlying cause remains, it can only be a risky operation at best. Am I on the right track with this?

Assuming the pressure switch is faulty, is it difficult to replace it? Again I'm totally not handy and never did this before, but the pressure switch replacement seems pretty easy, it has only 2 cables(purple) and 2 hoses(square connected to the collector box). Is there more to it? e.g. does it need any calibration or anything after the new one is installed? Wondering if a total newbie like me would be qualified for the job.

Thanks.
 
  #13  
Old 12-09-15, 12:51 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,499
Received 1 Vote on 1 Post
>



Shame on that guy.


It's rare for a pressure switch to be bad. If a pressure switch stays open, it's FAR more likely that there is a defect somewhere in the furnace that needs to be corrected --- other than the pressure switch.

If the pressure switch doesn't close, a manometer can be used to measure the pressure being applied to the pressure switch. If the pressure measured isn't negative enough that the pressure switch should close, the pressure switch is OK since it SHOULD NOT close.

If the pressure measured is negative enough that the pressure switch OUGHT to close and it's not, THEN the pressure switch is bad and should be replaced.

Also, by using a manometer, when the problem is identified and corrected the repair will be confirmed because the pressure will be at the correct level again.

Unfortunately, way too many repairman either don't know how to use a manometer correctly, don;t have a manometer and the fittings needed to use it, or are sloppy and don't use it when they ought to to get a correct diagnosis of a problem.
 
  #14  
Old 12-09-15, 06:49 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,026
Received 2,943 Votes on 2,656 Posts
You have a high end high efficiency furnace and the pressure switch is very critical of proper vacuum.

As I think further on this problem since it started early is that you may have a flue installation problem.
 

Last edited by PJmax; 12-09-15 at 07:07 PM.
  #15  
Old 12-09-15, 09:45 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
The gas company tech was probably not even certified; it has some disclaimers saying something like they don't repair or replace parts, the translation of which would be 'we only care about gasline safety'.

Agreed; manometer is essential to get to the bottom of this/pressure switch. Actually the certified tech is through a friend. What's troubling is he mentioned he would switch the 2 pressure switches to see if one of them is faulty; I'd rather he not touch the other furnace at all since it's working normally!! So I asked him to bring his manometer. Hopefully he will do so.
 

Last edited by armstronghelp; 12-09-15 at 10:02 PM.
  #16  
Old 12-09-15, 09:56 PM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
Yes I do understand now that the switch is indeed a pivotal prerequisite for safe operation.

He's got a new pressure switch part; I hope the cause is just a faulty switch(I heard Armstrong furnaces had a bad batch), which will make things a lot easier. He's certified who I got to know through a friend. But I don't have much confidence in him; heard too much about some repairmen will just follow the error code rather than dig deeper for the real root cause, like just replace the part indicated by the code so that the real problem remains so they will need to come back again and again...how depressingly troublesome. He's coming in tomorrow morning by the way so I may not hear back from you by then re what kinda flue problem will cause this. Fingers crossed he would dig deep and resolve this once for all.
 
  #17  
Old 12-10-15, 09:40 AM
A
Member
Thread Starter
Join Date: Dec 2015
Posts: 11
Received 0 Votes on 0 Posts
Okay he made a quick visit this morning; he did bring the manometer to check the pressure while the inducer was on...The reading was '1' (my pressure switch has -0.65 PF) so he said pressure was good so the issue was definitely the switch(though I'm cautious, I'd agree with this). I asked if the new switch part he got He got from the distributor was the same, he said no but close enough (the new Honeywell also has 0.65 WC PF specification so should be okay?) After he left, I waited for the furnace to run through the full cycle after reaching temp target set by the thermostat. I think it's in the clean now.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: