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  • Furnace Won't Light (fixed)

    Executive Summary: My furnace wouldn't light. Fixed it.
    Are there any furnaces out there that come with an LCD digital readout that displays error codes?

    Okay.

    Now the whole story:

    Monday evening I came home and noticed that the house seemed a bit cool. Checked and the thermostat read 19.2 but it was set to 21c. So there was a problem. I went downstairs and cycled the furnace breaker. The furnace then fired up ... but not really. It would turn on, but not ignite, and then turn off again after 10 seconds.

    Our furnace is a Ruud Achiever 90. A basic model high efficiency, installed in December 2006, so completely out of warranty.

    I did some googling and found a diagnosis guide which was pointing me toward the ignitor. I thought that the ignitor was probably dead, as I read online that they only seem to last 3-5 years and that I should keep a spare on hand. Right. I dismounted the ignitor but left it hooked up and cycled the furnace again, and the ignitor stayed stone cold. Didn't look cracked or broken, though. So I looked online and you can get them from amazon (.com!!!!) for about $22. Can't get them from amazon.ca. Also could not find any parts place here in London.

    I gave up and called the heating company. They nice guy told me that house calls after 7pm start at $300. So I told him to come in the morning, since we would be okay overnight. (It wasn't that cold on Monday.)

    Tuesday morning the house had dropped another 2 degrees, and was getting chilly. The guy showed up and spent an hour working on our furnace. Good thing I called, as the ignitor was fine. The problem was that the ignitor was not getting turned on. There are a couple of vacuum switches. Both of those have to trip before the ignitor turns on. And the ignitor turns on before the gas turns on. It's a pretty slick bit of engineering.

    He thought that either the exhaust flue was clogged (leaves, bugs, nest, whatnot) or the drain line was plugged, as that is what the vacuum switches hook up to. He blew out the drain line -- looked a big gunky, but still flowed. And also verified that the vacuum switches both worked. I went outside and checked the exhaust flue -- seemed clear, but I banged on it a bit, and then the furnace lit up. He cycled the furnace 3-4 more times and it lit up each time, so we concluded that there was a small blockage at the exhaust that I had knocked loose.

    End of story, pay the bill, thank-you-very-much.

    Not.

    This morning (Wednesday) the house was 17c again when we got up. Brrr.

    I went down and checked and the furnace would not ignite. Not at all.

    Being the handy guy I am (read: stubborn), I first set about seeing what I could do, before calling the guy. In part, I'd watched him scratch his head a lot yesterday over our situation. I checked the vacuum switches myself -- both clicked. In fact by sucking on the line you could get the furnace to ignite. (Of course you'd eventually pass out since it's impossible to keep sucking on the line forever... ) We double-checked the drain line and blew out some more gunk -- poured some clean water through to flush things out. (There is an "vent" in the drain line where the humidifier hooks up, so I was not pouring water in the furnace, don't worry!)

    The tech mentioned yesterday that they sometimes feed a golfball in from the outside, to let it rattle through the flue pipe, to make sure it is clear. So dismantled the outside flue pipe cover (I have an old metal cover that dates probably from 1984, so it is not a simple elbow like on modern installations) and first tried sucking with a shop vac looking to clear debris, and then fed in the large marble (golf ball wouldn't fit) and it came all the way into the furnace. So that line was NOT plugged.

    So now what?

    Process of elimination had me looking at where the vacuum switch hooks up to the power vent fan.

    I didn't take any photos, but I found this picture online of a similar furnace:
    ruud1.jpg

    If you note the arrow -- that is where the line from the one vacuum switch hooks up to the power vent fan.

    Both the tech and myself had removed that line several times during our attempted diagnosis. This time I actually looked INSIDE the nipple connection, and saw what appeared to be a spider web or moth chrysalis. So there we have it. I dismantled the fan housing and blew it out with a compressor -- no dice. I then pulled out a pick and poked at it. The nipple hole was essentially 100% clogged with mineral deposits (calcium I suppose?) from the condensate or maybe from bits of moisture running back down the flue.

    I cleared that out and the furnace fired up. Tested it a few times, and it fired up every time.

    The house has heat again. Hopefully that is it.



    So the question: Are there ANY furnaces on the market that have a digital readout that shows error codes or error messages?
    It just seems to me that this problem could have been fixed quicker. The furnace "knew" that vacuum switch was not tripping, so it would have been nice if it could display a code or message that told me or the technician where to look.
    It's not about you.
  • Thread Continues Below...

  • #2

    Re: Furnace Won't Light (fixed)

    Re: Furnace Won't Light (fixed)

    I have a Lennox that has a red flashing LED that will produce codes when something is wrong, and my last house had a Carrier with the same feature. It gives a starting flash and then you count the flashes and pauses to get a 2 digit number. Usually points you in the right direction but last time I had to call the technician anyway because it needed a new motor and it was warranty.
    Be careful when you follow the masses...sometimes the 'm' is silent.

    Comment


    • #3

      Re: Furnace Won't Light (fixed)

      Re: Furnace Won't Light (fixed)

      Both our Goodman and York have the flashing light troubleshooting guide as well. Both are 1-2 years old.

      Comment


      • #4

        Re: Furnace Won't Light (fixed)

        Re: Furnace Won't Light (fixed)

        You done good!
        Egon
        from
        The South Shore, Nova Scotia

        Comment


        • #5

          Re: Furnace Won't Light (fixed)

          Re: Furnace Won't Light (fixed)

          ps: and how about a simple audible alarm, either on the furnace or the thermostat, so we actually KNOW when the furnace stops working, instead of 8 hrs later when the house starts to cool down.
          Bryan @ Woodstock likes this.
          It's not about you.

          Comment


          • #6

            Re: Furnace Won't Light (fixed)

            Re: Furnace Won't Light (fixed)

            Originally posted by ArtMulder View Post
            ps: and how about a simple audible alarm, either on the furnace or the thermostat, so we actually KNOW when the furnace stops working, instead of 8 hrs later when the house starts to cool down.
            According to another thread you can probably get one to sync with your phone (not my phone though!)
            Be careful when you follow the masses...sometimes the 'm' is silent.

            Comment

            • Thread Continues Below...

            • #7

              Re: Furnace Won't Light (fixed)

              Re: Furnace Won't Light (fixed)

              Since most people have electronic thermostats these days, you would think a standard interface would be built into it to report codes from your furnace.

              Funny that this is not the norm these days.
              Steve The Drill Sergeant
              Check out MyShopNotes on YouTube.

              Comment


              • #8

                Re: Furnace Won't Light (fixed)

                Re: Furnace Won't Light (fixed)

                My furnace is annoying. I've had endless problems with it. It has a Honeywell SmartValve that has a blinking LED to indicate what the problem might be. The problem is the SmartValve itself doesn't seem that reliable and it's mighty expensive here in Canada (robbery). I don't know how many times I've gotten up on the morning to a cold house. Once it was the SmartValve (and I got charged $300 to replace it). That lasted about a year or so and we started having problems again and the HVAC said it was probably the SmartValve again but his supplier was totally backordered. So, I ordered a SmartValve from the States instead (for about 1/3rd the cost, I might add) but also bought a new HSI (hot surface ignitor). I replaced the HSI and then the furnace had no problems for a year. This year, the same problem started again and I figured, "okay...maybe it's time to get an HVAC guy to finally replace the SmartValve" but I noticed that I could *always* get the furnace to start by power cycling it and wiggling one of the connectors to the SmartValve. All connectors are in tight but there's clearly some electrical connection that's not quite snug. So I stuffed a small piece of V-shaped metal to the side of the connector to apply a bit of lateral pressure to it and the furnace has been working fine ever since. I'll take a closer look at the connectors/pins later. :P I still have a brand new SmartValve sitting in a box waiting to be installed...when the day comes, at least I won't have to fork out $300 just for the part.

                Given the primitive "technology" employed in these HVAC parts, it's pretty much highway robbery what they charge (at least in Canada). My co-worker's furnace had problems recently and the HVAC guy charged $75 to diagnose the problem (reasonable) and wanted $400 to replace the venter fan...a part that you can order from Amazon.com for $89. :P

                Comment


                • #9

                  Re: Furnace Won't Light (fixed)

                  Re: Furnace Won't Light (fixed)

                  Learning experience: we bought high efficiency units because of some grants that were available at the time. The sales guy that they hired to deal with the surge of orders due to the grants 'threw in' the 10 year extended warranty to beat a competitive offer and get our business. He neglected to tell us that you have to have the units (A/C & furnace) serviced twice a year by their company and replace the $219 Merv 16 air filter too. Total cost to keep the 'free' extended warranty valid was more than $500 / year on new equipment! We found out on year 3 when the motor went and they didn't want to honour the warranty because they had not serviced it. Next time- mid efficiency unit without extra warranty.
                  Be careful when you follow the masses...sometimes the 'm' is silent.

                  Comment


                  • #10

                    Re: Furnace Won't Light (fixed)

                    Re: Furnace Won't Light (fixed)

                    Art, One thing to remember is all the safety switches thermostat etc are usually daisy chained together ending with power to the gas valve, that then turns the main burner on.Why tech did not jump each safety in turn with a couple of roach clips and a wire I don't know .He could diagnosed it without so much effort. Look at the logic diagram.However anything within the electronic module is not so easy

                    Comment


                    • #11

                      Re: Furnace Won't Light (fixed)

                      Re: Furnace Won't Light (fixed)

                      Well done Art. I'got a tip for anybody whose H E furnace is around 8-10 yrs old. Around my area a lot of installers were putting a P trap on the exhaust pipe outside the house. Reason unknown. My Son's furnace would fire up & run for less than a minute 7 cut out, then repeat etc. Middle of winter, couldn't get the installer in for 3 days, so I had a look. After doing the usual checks I realized I was hearing a gurgling sound. Traced it to the P trap outside which was full of condensation, created back pressure & shut the furnace down. I drilled a hole in the bottom of the P trap & it was fine. When the installer got there he cut the trap of & admitted that a lot of his calls were for that problem.
                      There may still be some traps out there that need to be cut off.
                      Paul W.

                      Comment

                      • Thread Continues Below...

                      • #12

                        Re: Furnace Won't Light (fixed)

                        Re: Furnace Won't Light (fixed)

                        I have a Lennox and as mentioned above it has flashing LEDs that give some help but it's not as good as OBD.

                        I had a situation just like yours at this time of year last year. In my case it was the ignitor that was shot. The flashing LEDs told me that the furnace "failed to start". Thanks for that detailed analysis, I thought. I measured the voltage on the leads to the ignitor when it was supposed to be on and found I had voltage so I knew it was the ignitor itself that was toast.

                        This is where I got my replacement ignitor:

                        https://www.amresupply.com/

                        The replacement part I got was the exact same as the original, same manufacturer's name and part number printed on it.

                        Why an installer would put in a P-trap on a flue vent is beyond me. There's tons of condensate coming out of the flue gas. Every now and then during the winter, it's worth checking the furnace vent pipe, there is often an ice "stalagmite" under it. It should be knocked over so that ice cannot block the pipe.

                        Comment


                        • #13

                          Re: Furnace Won't Light (fixed)

                          Re: Furnace Won't Light (fixed)

                          I also have a furnace with a pricy filter although not as costly as yours. Mine is a 5" pleaded 20" x 20" and my local guy wants $85.00 each. I buy from this place http://filtersolution.com/ in the US and get 2 for $62.00, even cheaper if you buy more. Prompt service and they will ship USPS so you avoid the customs charges the couriers usually apply. No affiliation only a satisfied customer.

                          Tom

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                          • #14

                            Re: Furnace Won't Light (fixed)

                            Re: Furnace Won't Light (fixed)

                            My furnace is a Lennox signature series. It has a flashing light, but also a pair of seven segment displays side by side. When the furnace fires up it will show the following in blinking lights
                            h (Heat) or C for cooling
                            Then 2 digits which is the percentage. Its a unit which can go from 40-100 for heat output.
                            then A for air and a digit,
                            then 2 more digits showing the amount of CFMs.

                            It has a 16x25 5" filter Merv 10. It can be pricey, but there is a shop in toronto that sells them for $40 which is pretty reasonable, they last for 6 months and definitely keeps the dust down.

                            Comment


                            • #15

                              Re: Furnace Won't Light (fixed)

                              Re: Furnace Won't Light (fixed)

                              Originally posted by ArtMulder View Post
                              Executive Summary: My furnace wouldn't light. Fixed it.
                              Fixed it AGAIN...

                              I'm torn between grumpy that it happened again, and happy that I knew exactly what to do to fix it, saving a $150+ service call.

                              Original post is from November 2013, It is now March 2015, so it's only been 16 months, give or take a bit.
                              It's not about you.

                              Comment

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