Fixed my home heater... eventually

Thought I'd relay my experience with repairing my home heating unit a few days ago. Maybe it'll help someone else.
Last Friday when I went to sleep, the heat was working. When I woke up a few hours later, I noticed the house was cool; checked a vent and it was blowing tepid air. So I went to the furnace (York P2DP downflow) and opened the panel, and sure enough, no flame to be seen. I shut it off for a few minutes and then restarted it. The problem was obvious; the ignitor gave one little bright spark and then sat there. Close examination showed a tiny break in it.
Called the local mom-and-pop parts dealer; they had a generic in stock. Did a quick web check and the generic (AF101) seemed to be a good fit for the furnace, so I ran down and grabbed one. Got the usual caution about not touching the element, but already knew that. So I bent the wires to use them as a handhold to move the element into place, finally got the screw started in the teensy little space available and screwed it down. Then I turned on the heat.
There was no noticeable glow from the ignitor. Instead, below the point where I could see it, something glowed very bright white for a few seconds, then the ignitor cracked in two. Natch, the store was closed by then. As the heat dropped in the house, I decided to use a propane torch as an ignitor for a temporary run of warmth. That worked for a while; the gas kept shutting on and off, but it worked for a while. Then it no longer let the gas flow. Oh well, we were warm and tomorrow's another day.
Next day I send the wife for a new ignitor. I wasn't even gonna ask, but she did and they replaced it free of charge. (That's what I like about the mom-and-pop shops; unless you're a regular, the big places usually won't give you the benefit of the doubt.) Brought it home and tested it outside the furnace; it worked and I installed it.
This time I got a nice bright orange glow. But no gas. So I removed the access panel and found a light blinking four times. Looked up the controller number on the web, couldn't find an exact document but did find similar units that said four flashes was the roll-out switch. That was fine. So I started blindly following a troubleshooting guide until I found a list of the flash codes on the controller itself; four flashes actually meant the limit switch. Checked it and it was indeed bad.
I wiggled it and prodded it and it came back to life temporarily, so we had heat for the weekend. Got a new one Tuesday and replaced it.
Here's the part many people will be interested to read. Now that the new limit switch is in there, the gas no longer shuts off and on during a normal heating cycle, as it did when I was using my torch as the ignitor. Apparently the switch was touchy enough that it was overcycling the heat. I'd call that subjective, except that the past few days the temperatures outside have fallen quite a lot, with a high of about 30 now and a low of less than zero F. At those times before, the heat used to run almost continuously; now it cycles almost like it did when it's forty outside, except less often.
So even if your furnace is working properly, if it's old you might consider changing the limit switch on principle. Mine was available for just under $6 on the net, though I paid $10.74 at the mom-and-pop for immediate gratification. :) I bet this month's heating bills are going to be lower than they have been for the more temperate months preceding.
--
All relevant people are pertinent.
All rude people are impertinent.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

My oh my, you threw parts at it until it worked. That makes you fully qualified to fix everyones furnace now. Aren't you proud of yourself?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Al Moran wrote:

I thought I made it clear that I did NOT throw parts at it.
I diagnosed the ignitor the easy way. I watched it when I turned on the heat. Instead of glowing, it gave one bright flash from one tiny point on the ignitor. Physical examination of the ignitor showed a break in the element, surrounded by material that was lighter gray than the rest of the element. Any moron, even me, can tell that that was a defective ignitor.
When the heat didn't come on, I followed the diagnostic procedure the best I could without a manual, until I found the correct procedure written on the controller but hidden by a gaggle of sloppy wiring. It said "limit switch". I checked the limit switch and it was defective.
I've been troubleshooting electronics, appliances and HVAC probably since before you were soiling Pampers. My first full-time job at it was in 1967. And yes, I am proud of myself for being able to follow simple, time-tested diagnostic procedures to diagnose and repair a problem, thank you very much.
And unlike you, I am able to diagnose the fact that the old, intermittent limit switch had a pronounced effect on the operation of my heater.
And apparently unlike you, I was willing to share my newfound knowledge with the rest of the newsgroup. I don't see much helpful information coming from you.
--
All relevant people are pertinent.
All rude people are impertinent.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Bullcrap! You've done nothing but toss a part at a symptom. Try repairing the cause. Symptoms are easy. Got a cough? Take a cough drop. What the hell does that solve? Your diagnostic skill suck. Bubba
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bubba wrote:

You must work for the crap company that first worked on my furnace. When I found out by accident that there was a serious recall on my furnace, I called York and was assured that the people whose sticker was on the furnace (they installed it when the house was new) were just great. So I called them Now bear in mind that they not only got their standard service call fee, and free parts, but they got an additional $25 for this. We made the appointment in April; when we finally pestered them in October, they deigned to come out in November. While doing the upgrade they broke an interlock switch. They promised me a service call to replace the switch free. That was two years ago and they still haven't bothered to come back and repair the damage.
I'll bet you work for them. You sound like the kind of hack they employ.
In 39 years two people have complained about my diagnostic skills. The other apologized when ten people told him he was wrong. You haven't even a clue because you haven't seen me work.
So go off and rob some poor sucker tracking down why a ten-year-old ignitor burned out for your $80 per hour. There's enough suckers out there that you can get by with it most of the time.
--
All relevant people are pertinent.
All rude people are impertinent.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

So since 1967 (39 years) you still havent figured out that if a part goes bad, its not always because "the part just went bad". Like I said, "Your diagnostic skills and thought processes suck". Too bad you wont figure it out. Hopefully you wont kill someone in the process. Your parts changing ability and inability to figure out why a part went bad will only cost you much much more money in repairs later. Oh well, "must suck to be you". By the way, my house is nice and warm and my limit doesnt cycle because someone installed my system and set it up properly..............ME! Bubba
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bubba wrote:

I'm eagerly awaiting your genius description of how an ignitor develops a hole in its spiral structure after nearly ten years.

I'll try and remember everything you've taught me.

It's pretty great to be me.

And mine is nice and warm and my limit switch doesn't cycle because its ten-year-old furnace was properly repaired by a competent technician... ME!

With a name like bubba, <http://tinyurl.com/3ztz might be more your speed.
--
All relevant people are pertinent.
All rude people are impertinent.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yeah but at least my wife doesnt look like yours. http://tinyurl.com/gz5oy
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

So you poked and prodded and you think you have it working now? Here is a little clue for you to ponder, Einstein. Your igniter went bad and.........more importantly, your limit went bad. Hmmmmmm, why did that limit go bad in the first place?? Must be just cheap shit they keep putting out, huh? You know, Mexico, Thailand, Japan. Those guys just put out cheap parts. Yeah, that must be it...................I hope your saving your money up for that new heat exchanger. Bubba
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I am a service tech for office type machines, 30 years of troubleshooting...
anyhow I think the original poster did a excellent job of troubleshooting.
sometimes 2 problems occur at the same time.
incidently I have seen my furnace short cycle:( will check the limit switches thanks to this poster.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.