dead furnace


Well, I'm sitting here in my kitchen with the oven on and open... furnace quit about 9:30 or so. Home warranty people recommended some guy that can't come out tonight. None of the "24 hour service" HVAC people in the phone book apparently really do offer 24 hour service... so for lack of anything better to do, anyone want to walk me through trying to figure out what I need?
Furnace is a Ruud 90+ gas fired forced air unit. When I turn up the thermostat, the blower kicks on, I hear the gas valve click open and then the main blower kicks on, but the burner never ignites. It'll run for a couple minutes, blowing cold air, and then shut itself off. I'm guessing it's either the gas valve or the ignitor, but how to tell which one?
nate
(kinda scared to go to bed with the oven going, I realize that this is not a recommended method of heating one's house.)
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Nate Nagel wrote:

Update: after some googling I determined which component was the ignitor. I disconnected it and found it to be completely open. I'm guessing that this is the problem? Should I bother to place a service call or just run down to the parts place as soon as they open and pick one up? (better yet maybe two; googling also seemed to indicate that this is a common failure of "high efficiency" type furnaces.)
nate
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If the ignitor is open, plus you can confirm you're getting 110v across the ignitor leads, then it's probably the ignitor. I would just buy one myself. Don't get 2 of them yet just in case it isn't the problem.
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wrote:

If you cant get a serviceman out anyhow, you may as well wait till morning and get your own part, providing you know how to change it.
I've heated with the oven on for short periods of time. I would not leave it on all night though. Get it hot in the house and use lots of blankets. An electric space heater in the bedrooms would help too. I assume you know how to use them safely, and not near the bed, where a blanket could fall on them.
If this fixes your problem, I would buy a spare ignitor if you plan to stay in that home for years more.
I have a feeling if you placed a flame in the burner at precisely the moment the ignitor was supposed to ignite, you might get the furnace started, but only until it shuts off again.
I'm glad I have a wood stove. Its always there if the furnace quits, and saves on fuel too. I just have to keep reminding myself to use it and not be lazy to haul in wood.
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snipped-for-privacy@my.com wrote:

Done and done. It was the ignitor. Hit the appliance parts place before they opened (at 8:30) was at home and had heat by 9AM.
Ended up using the oven all night and moving the electric oil-filled radiator thing back and forth between the basement and 2nd floor. I do have a wood stove but never stocked up on wood having just bought the place not long ago.
Total cost of repair was $55ish (including spare ignitor) so I guess it's hardly worth going to the home warranty people at this point, what with a $50 deductible and all. Only peeve is the fact that there's tons of HVAC people in the phone book that advertise 24 hour service and yet you can't get someone after hours when you really have an issue. (yeah, I was going to "let the pros handle it" but it is still apparently easier and faster to just DIY.)
Now that I've paid attention to how this works, I could have diagnosed it instantly had I known what to look for. That ignitor sure is bright when it heats up! I thought about your idea of trying to manually light the burner, but was too chicken to actually try it. I've done it tons of times with recalcitrant stoves, but I just had this possibly irrational fear of causing a massive fireball in my basement...
nate
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wrote:

Glad you got it going and was a relatively easy and cheap. That 24 hour service is apparently only for the city mayor and police chief :)
Get yourself a few days worth of firewood if you got that woodstove, you may as well have it useful if you need it again.
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Good for you. You've learned three important lessons 1. How to diagnose common heater problems 2. Home warranties are pretty much useless 3. You can't always rely on the pro. There are some very good ones though.
If you have to rely on a pro for everything, home ownership is much more expensive. You did good.
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It's always a good idea to be familiar with the sights and sounds your appliances make when they're running correctly, since when they break you may be able to tell immediately what is missing. My furnace is one of the 80% types. When it starts, the inducer fan runs for a few seconds, then the pilot light turns on and is ignited (spark igniter), then after a few more seconds the main gas valve opens and the main flames appear. A dead igniter would give no sparking sounds.

It's probably safer than in a stove, because of the forced draft in a HE furnace. That guarantees you won't get an accumulation of gas in one spot. If your igniter lights the main flame directly, you could probably do the same thing with a barbecue lighter held in about the same place at the right time. With a furnace like mine, I'd have to use the lighter to get the pilot flame lit at the right time, or the safety circuitry would never open the main gas valve.
At times like this, I wonder how much it would cost manufacturers to include an old-fashioned standing pilot light in addition to the on-demand ignition. It might remain unused for 20 years, but when your igniter fails you'd be able to light the standby pilot and have heat.
    Dave
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Since you've got the problem diagnosed, replace the ignitor yourself. And it's a good idea to buy two, as they are a common replace part.
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wrote:

Just wander over to a local department store and buy a couple 1500 watt electric space heaters. Those will keep the house habitable for a day or so, until you can get the furnace repaired.
Plug them in on different circuts.
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