No heat....help with furnace question, please!

#21 02/14/10, 11:18 PM

I know you said you couldn't afford a repairman but you have a 27 year old furnace that hasn't been serviced in 10 years . I'd highly recommend that you have it inspected & serviced by a professional if at all possible .

cc-rider · #22 02/14/10, 11:21 PM

It's natural gas, so there is none to run out.....
wait a minute....
yeah, the stove is working so I have gas.

Ok...heading down again to see if I can find a reset button on a circuit board. My furnace is mounted up near the ceiling....horizontal, instead of standing vertical, if that makes any difference. What would a circuit board look like, and where would it be? You mentioned behind a door or plate???

tinknal · #23 02/14/10, 11:23 PM

Good luck, I've shot my limited wad of knowledge on gas furnaces and need to go to bed!

cc-rider · #24 02/14/10, 11:24 PM

Quote:

Originally Posted by tinknal

OK, one more question. I doubt this is your problem due to the age, but my 90 percent effecient furnace installed in 2001 has a little vacuum powered solinoid. It has a rubber hose attached. Sometimes the hose fills with condensation and the solinoid will not work. When this happens I pull the lower end of the hose off the nipple, drain the water, reinstall, and turn the furnace off and on again. Starts right up.

There is an orange rubber hose that runs somewhere up by where the igniter or thermocoupler, or whatever that thing is. I can't find either end, though. I'll check that out, too.

Ok...heading down again....

cc-rider · #25 02/14/10, 11:25 PM

Quote:

Originally Posted by tinknal

Good luck, I've shot my limited wad of knowledge on gas furnaces and need to go to bed!

Hehhe. Thanks Al! You gotta get to bed so you can get up and start cooking tomorrow! Did you have a good Valentine's Day crowd??

Thanks again...

blooba · #26 02/14/10, 11:32 PM

there are usually 2-3 "boxes"

the top one has the A-coil(air conditioning) usually sheetmetal like the duct work

the next one has the burners(user accessible) Part of the "Furnace"

the bottom one(where the air comes into) (usually need screwdriver or nutdriver) contains the "brains" of the furnace. Same color of the burner access panel

There are a few of furnaces out there that have everything in one big panel, but those are usually older than yours.

You will know if u found the circuit board. it should be about 6"x8" and easily accesible

http://homerepair.about.com/od/heati...ectr_ign_8.htm Yours will look like an antique board compared to this...lol
Here is a furnace not installed without the A-coil. http://www.rheem.com/product.aspx?id...C-4C6DFC771D50
the bottom panel usually has the control board

blooba · #27 02/14/10, 11:59 PM

Well hate to leave ya out in the cold (literally) but its getting past my bedtime too. If you cannot fix the problem try to warm the house as Al said

Quote:

Originally Posted by tinknal

I've done this in a pinch. Use a long grill type lighter. Turn the furnace off then on again. Hold the lighter just above the ignitor. It will heat up the sensor that turns on the gas and the gas will flow and ignite. Turn your thermostat way up. You will have to reoeat this process every time the furnace reaches temp and shuts down. Set it at 85 or so and the temp shouldn't drop to bad by morning.

Even if you get it fixed or use Al's tempfix get a HVAC guy in there to at least inspect it ASAP. There are safety switches that can go bad and it may leak deadly odorless gases into the house. It will make you goto sleep and never wakeup again. Not something to be lax on.

Good luck.

cc-rider · #28 02/15/10, 12:00 AM

Ok....the fan that was running is the exhaust fan...not the fan that pushes the air. I think that exhaust fan comes on whenever it thinks the furnace should be running...

cc-rider · #29 02/15/10, 12:06 AM

Thanks for all your help, guys! I'll call a repairman in the morning...sigh.

blooba · #30 02/15/10, 12:08 AM

Try lighting it by hand, if it runs correctly its the ignitor
If not its the control board. dont let it burn for more than a few minutes without the blower coming on(it will overheat)
good night and good luck, keep us posted

cc-rider · #31 02/15/10, 12:21 AM

Thanks. Egads...I didn't realize how late it was! Gotta be getting up for work in a few hours.

I'll let you know tomorrow what happens. Thanks again.

Oh! And nice to see you on the board, blooba. Where are you from in NW Ohio?

sammyd · #32 02/15/10, 07:16 AM

Make sure you do not have a buildup of ice on the vent that goes outside.
If the exhaust fan runs but does not make a sufficient vacuum the unit will not start.
Sometimes there will be a big icicle on the vent pipe or an ice pile on the ground that reaches the opening that you can knock off and things will be hunky dory...

blooba · #33 02/15/10, 07:37 AM

I am in Pandora.
The ice buildup maybe the problem, I know one of my gutter downspouts are frozen solid. The temps have been right for ice buildup. although since its not a high effeciency it probably is running flue temps too high for ice. You did check that condensate line that Al mentioned right?

cc-rider · #34 02/15/10, 08:35 AM

Quote:

Originally Posted by sammyd

Make sure you do not have a buildup of ice on the vent that goes outside.
If the exhaust fan runs but does not make a sufficient vacuum the unit will not start.
Sometimes there will be a big icicle on the vent pipe or an ice pile on the ground that reaches the opening that you can knock off and things will be hunky dory...

I'll have to check that. Thanks!

For the last few weeks, a lot of times when it kicks on, it makes an explosion sound. Scared me the first few times and I'd run down and check to make sure nothing blew up. Got used to it after awhile. I wonder if that was a warning that something wasn't quite right?

cc-rider · #35 02/15/10, 08:37 AM

Quote:

Originally Posted by blooba

I am in Pandora.
The ice buildup maybe the problem, I know one of my gutter downspouts are frozen solid. The temps have been right for ice buildup. although since its not a high effeciency it probably is running flue temps too high for ice. You did check that condensate line that Al mentioned right?

Yep, pulled that rubber tube off and nothing came out.

I've got a call out to a repairman, so I'll see what he says. Of course, he's the guy that told me 10 years ago that I needed a booster fan to force more air so that I'd have heat in the upstairs.....and I pointed out that I didn't have floor vents up there anyway.

blooba · #36 02/15/10, 08:39 AM

Sounds like a gasbuildup before igniting, probably your ignitor then.
Did you try lighting it by hand? You will have to turn the furnace off then back on since the thermocouple cuts off the gas when no flame is detected after a few secs. Might need 2 ppl for that job.

cfabe · #37 02/15/10, 09:24 AM

In the furnace there is something called a flame rollout switch. If for some reason when the burner lights there is a "whoosh" of flame like you mentioned, it could have tripped that switch. They usually automatically reset but it may be a manual reset, usually pushing back in a button that has popped out.

Based on the fact that the furnace has an exhaust fan, it is a high efficency furnace. They usually have a sequence that they go through to start up. On yours it would usually go something like:
1. Call for heat from thermostat
2. Turn on exhaust draft fan, monitor vacuum switch to make sure draft is good
3. Start ignition spark
4. Turn on gas to pilot, monitor thermocouple in pilot flame to make sure pilot lights
5. Turn on main gas to burner, monitor thermocouple to make sure burner lights
6. Monitor flame roll out switch to make sure no flame rolls out of burner
7. Wait for heat exchanger to heat up, then turn on main air blower fan to give heat to house
7. While heating, monitor the high temp limit switch to make sure heat exchanger doesn't overheat, and monitor all other safeties as well.

If any of the steps fails, the furnace shuts down, usually waits a few minutes and tries again.

So if you are getting the exhaust fan coming on, but you do not hear/see the sparking to start the pilot light, the problem could be that it is not getting proper draft (blocked exhaust) or the spark ignition system has failed and is not providing spark.

On these older units, the spark ignition systems get flaky with age. You can sometimes clean the probes with sandpaper to help them out. My mom's place has a similar furnace with the intermittent spark pilot ignition, and after a couple years of fiddling with the spark unit, I replaced it with a retrofit kit. Works fine now, cost was about $150. But on a 25 year old furnace, you might consider complete replacement if planning to stay in the house for a while. 25 years is end of life timeframe for any furnace.

cc-rider · #38 02/15/10, 11:38 AM

Well, the guy came out, turned it on, and the blasted thing worked fine!!! Grrrrr.
He spent a lot of time, however, showing me all the stuff that he needed to check...pretty much along the lines of CFabes comments. He'll have to come back if and when it isn't working. But I'm keeping my fingers crossed.

He noticed that I have a tiny hole in the manifold (or something) that he found with a camera probe that is bad, bad, bad, and said he'd ignore it this time, but if has to pull it out to clean it, he'll have to tell me it will need replaced. I have a carbon monoxide detector, so I'm not too worried at this point.

He said the life of one of those furnaces is about 15 years, so I'm already about 15 years PAST that. I guess I should feel lucky. Except my house is for sale and a crappy furnace won't help matters.

Thanks for all your help last night, though!!! I felt blessed to have friends!!!!

blooba · #39 02/15/10, 01:09 PM

A home inspection will probably show the hole in the manifold. You may want to think of replacing it as an added bonus to the buyers. Glad it works for now. Hopefully no more problems.

cc-rider · #40 02/15/10, 01:30 PM

I've been thinking that I need to look into that home buyer's insurance policy. I think it is about $500, but it covers the new owners for anything up to one year after they buy the house. It would replace the furnace....but I'm not sure if it is at 100% or 50% of the cost. Either way....it'd probably be good.