Help with furnace

[gassy]

So on the coldest day of the year my furnace kicks. Bullet points to make an easier read.

• Automatic pilot--no match needed.
• Go thru all the motions--funace starts, gass attempts to light three times and whole unit then shuts off.
• During this I see no spark whatsoever...
• ?
• Have an appointment for 7:30 tomorrow am. We're at 60 now but it's dropping. outside temps of -1.
any ideas?
• Any photos of sand and sunny fun times are welcomed.

[legion]

I had a similar problem for years. The problem got worse the colder it got. I had the furnace company at my house three times and got three different solutions (none of which fixed the problem).

The only difference is that I had a spark--it would just take from a few seconds to light to never lighting.

Turns out the problem was........a vacuum leak.

I have a side-vent furnace (a blower motor pushes the exhaust out a horizontal vent). There was a vacuum tube that ran from the blower motor to the flame box. The tube was fine, but the flame box was not properly sealed. I taped it up with silver tape and have not had a problem since.

[legion]

Oh, and do you have any electric space heaters? You might want to run some to keep the temperature up in the house.

[einreb]

do you know what an 'ignitor is'? is it ok?

http://www.myhvacparts.com/Published%20HSI%20Educ.htm

[legion]

Weird. My furnace uses a spark to ignite. It has a lead that runs from the flame box to a control module. Much like a spark plug, its surface can become fouled and the expansion/contraction cycles can increase or decrease it's gap from the grounding components to the point it will not ignite.

Christian, I think your first step is to identify what kind of furnace you have.

[einreb]

Originally Posted by legion

Weird. My furnace uses a spark to ignite. It has a lead that runs from the flame box to a control module. Much like a spark plug, its surface can become fouled and the expansion/contraction cycles can increase or decrease it's gap from the grounding components to the point it will not ignite.

Christian, I think your first step is to identify what kind of furnace you have.

Chris maybe has the intermittent pilot type?

http://homerepair.about.com/od/heatingcoolingrepair/ss/furn_electr_ign_3.htm

this is the more common version...

http://homerepair.about.com/od/heatingcoolingrepair/ss/furn_electr_ign_4.htm

this is a good reminder. I need to go buy a spare! those little f'ers go out every few years. good for the hvac business, but a pita for the homeowner.

[legion]

Yep, that's what I have.

[ruf-porsche]

Originally Posted by gassy

So on the coldest day of the year my furnace kicks. Bullet points to make an easier read.

• Automatic pilot--no match needed.
• Go thru all the motions--funace starts, gass attempts to light three times and whole unit then shuts off.
• During this I see no spark whatsoever...
• ?
• Have an appointment for 7:30 tomorrow am. We're at 60 now but it's dropping. outside temps of -1.
any ideas?
• Any photos of sand and sunny fun times are welcomed.

You may need to clean the flame sensor. What kind of unit is it? How old is it? Go to youtube and search for a video on cleaning the flame sensor.

On my carrier unit (9 years old) I normally clean the flame sensor at the beginnng of the heating season. You can use a fine steel wool to remove the soot that builds up on it. One screw is all it takes to remove the flame sensor. 5 minute job, but if you have it service at a minimum 100 bucks.

Do your furnance used a spark ignition or a hot surface ignitor to ignite the gas (I'm assuming we are talking about gas)?

http://www.youtube.com/watch?v=yMDiQhaXSt4

Hey you're just a couple of click from my location.

[gassy]

Originally Posted by einreb

do you know what an 'ignitor is'? is it ok?

http://www.myhvacparts.com/Published%20HSI%20Educ.htm

Well that did it! My first foray into HVAC a success. I owe you a reach around.
Thanks

[legion]

What was the problem? What fixed it?

[gassy]

I replaced the ignitor --it had gone bad.
this thing:

[gassy]

Bigger pic

[cgarr]

What Ruf said, is the gas lighting? if so then the flame sensor is not working and it will shut down, usually just some sand paper across it will fix it, its just a steel rod on the opposite side of the ignitor. That way all the burners have to light before the system accepts all is well.

If the ignitor is bad and not lighting up you can manually light the furnace when the gas kicks on and at least warm the house for a bit.

After it tries three times and fails you will need to shut the power off to the furnace and back on to reset the controller. Then it will cycle again.

[ruf-porsche]

Originally Posted by gassy

Bigger pic

That's a Hot Surface Ignitor, it glows, like the glow plug on a diesel engine. The other kind of ignitor is a spark ignitor that spark like a spark plug.

If you ohm the ignitor it should around 75 ohms, if the ignitor is crack it will read infinite or open circuit.

I keep a spare flame sensor and HSI at home incase the furnance goes out at 2:00am.

[einreb]

Originally Posted by gassy

i owe you a reach around.

you have a pm.

[Tishabet]

Originally Posted by gassy

i owe you a reach around.

Originally Posted by einreb

you have a pm.

[cgarr]

Originally Posted by tishabet

+2

[legion]

And suddenly, I've lost interest in this thread.

[sketchers356]

Did you have an extra ignitor laying around?

[gassy]

No, I ran to True Value and they actually had one. $39.99