Furnace lights intermittently (but it's not the Hot Surface Ignitor)

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Old 02-11-13, 04:22 PM
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Furnace lights intermittently (but it's not the Hot Surface Ignitor)

I have a problem with my gas burning furnace, a 'Bryant plus 80t' model. (Preferred™ Series Plus 80t™ Gas Furnace - Bryant)

Problem: I'm only getting ignition intermittently -- and it seems to be more likely to ignite after it has *not* been on for quite some time.

I can report that it's not a problem with the Hot Surface Ignitor -- had a spare, plugged it in, & am seeing same problem. If I watch the furnace go through its entire cycle, it will try to power up the HSI at the correct point in time, blow gas, but the HSI won't glow or will glow very weakly, and then the gas shuts off. It then repeats a few more times before going into lockout.

Tested the plug that feeds the HSI with my ohmmeter. I seem to see a very brief surge in power around the time that the HSI should be kicking on, but I don't have time to see a stable reading before it goes back to 0.

And again: occasionally the HSI gets enough power to actually ignite. But this happens rarely...

Thanks in advance for your help!
 
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Old 02-11-13, 05:08 PM
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As soon as the furnace gets a call for heat......the inducer blower starts. As soon as that happens the HSI should be getting voltage. It should be glowing for at least thirty seconds before burner tries to light.

You will want to put your meter.....set for at least 120vac....on the HSI plug with it connected.
 
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Old 02-11-13, 05:21 PM
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Tested it again with the meter while HSI is connected. It's getting power very occasionally.. the first couple times my meter was non-zero, it was for a split-second and I couldn't get a reading.

Around the time of the 3rd ignition attempt it stayed on for a 3-4 second stretch; I was able to measure ~120V and the HSI started to glow. But then it went back to 0 before the gas kicked on, the HSI cooled, & it failed to ignite.
 
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Old 02-11-13, 05:35 PM
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You may have an intermittent connection at the HSI plug or where it connects to the control board. Try checking for voltage on those wires at control board. Be careful not to damage the pins.
 
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Old 02-11-13, 07:33 PM
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Cables seem to be well-seated, & checking voltage at the control board yields same result. Extremely brief uptick in voltage, but nothing sustained & no glow from HSI.
 
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Old 02-11-13, 07:49 PM
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One last thing to check. Connected to the draft inducer blower is a pressure switch. This switch sends 24 vac to the control board so that the board knows the blower is running and pressure is established. Using a meter check for 24 vac on the two wires on the switch. You should see voltage on the switch and when the blower runs and the switch closes the voltage will go to 0. (or vice versa)

If this checks out......it leaves us with a possible defective control board.
 
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Old 02-11-13, 08:18 PM
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Hmm... well that's no good. Am getting 110 vac coming out of the draft inducer pressure switch, when the motor is running.

The one time (out of about 10 tries) that I saw ignition, it stepped down to 60 vac (I think) after flame was up.
 
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Old 02-11-13, 08:28 PM
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There are two wires on the switch......correct ?

Your leads should be on those two wires.

You have your meter set to a scale just over 24 vac..... correct.
 
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Old 02-11-13, 08:38 PM
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Yeah, I'm puzzling over the 110 vs 24 vac too. Wondering if I measured the wrong leads. But It was a pair of wires from the draft inducer to the control board (ending in the same plug on the board as one of the HSI wires). Does that sound right?

In this picture here, I measured the red/black wires: http://i45.************/11lhpox.jpg
 
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Old 02-11-13, 08:45 PM
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take 2 on the picture:

 
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Old 02-11-13, 09:00 PM
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You WERE measuring the blower.

The pressure switches are those round items.
One has a brown and gray wire.
The other has a orange and yellow wires.
 

Last edited by PJmax; 02-11-13 at 11:16 PM. Reason: Clarification
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Old 02-11-13, 09:26 PM
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Thanks for hanging in there with me on this. Tried again & got the measurement you were looking for.. the top-left pressure switch, labeled LOW FIRE, does give me 24 vac when the inducer motor is OFF and drops to 0 when the inducer is ON. So... bad control board? My estimate is that this furnace is about 8 years old.

(Reading up, I see this is a dual stage furnace. I was only reading power out of one of the pressure switches, but I assume that's normal...?)
 
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Old 02-11-13, 11:20 PM
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Yes.....that's normal.

If you look at the pressure switches........the one in the back says low fire and the one in the front says high fire. So you have one for first stage and one for second stage.

It would appear that you have a defective control board.
 
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Old 02-12-13, 10:53 AM
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Yep PJ, you nailed it... the repair guy showed up today, I am now $115 poorer and he told me exactly what you did. Also tried selling me a new furnace, but that's a different story...

So he's checking around for a board for me. Says I'm looking at $650 to replace, but then again he also said he'd sell me a new ignitor for $250. Should I be looking into picking up my own? Is the install rocket science or can I copy over the same wiring from my existing setup?
 
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Old 02-12-13, 01:09 PM
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Look for a part number on the control board.....try googling it.

Otherwise post it here as well as the model number for your furnace and we'll look it up.

Shouldn't be an issue for you to install yourself.
 
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Old 02-12-13, 01:35 PM
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It's part number CEPL130455-01. Furnace is a Bryant, model 312AAV. Do you have a go-to source for this picking up a part like this?
 
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Old 02-12-13, 08:40 PM
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Yeah.......the bank......ouch Expensive board.

You will have to call or email parts places for the board. I see the old board at several places but very expensive. There may be a newer replacement that is not as costly.

Carrier Furn Control Board CEPL130455 01 CEBD430455 04A | eBay

Try:
Bryant Carrier Control Boards
 
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Old 02-12-13, 09:41 PM
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Ha! Yeah... price quote for board+install shot up to over $1k after the tech called his supplier. Needless to say I'm not happy spending that much on an 8 year old furnace; considering just buying a new one of a different brand for approx the same price if I install myself. Really disappointed with the Bryant double-whammy of no warranty & crazy expensive maintenance so soon.

I actually bought my spare ignitor from Arnold Service & was really happy with their service. But I didn't see my particular board on there... emailed them to ask if they have whatever Bryant is recommending right now for my furnace. We'll see if they have good ideas.

Thanks again for all the help. This is an awesome forum. If you've got a particular furnace that you think is better than the others, let me know. I'm in the market....
 
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Old 02-13-13, 02:03 PM
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<<
Yeah... price quote for board+install shot up to over $1k after the tech called his supplier.

Read more: http://www.doityourself.com/forum/gas-oil-home-heating-furnaces/488439-furnace-lights-intermittently-but-its-not-hot-surface-ignitor.html#ixzz2Koqfi3Se>>



I'm guessing the repair guy is figuring a $150 cost for the part and $850 to install it --- a half hour of work, probably.
 
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Old 02-14-13, 04:15 PM
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Final update: ordered the control board online, installed it this morning, & have a functional furnace and warm house right now. About 1/3 the price of paying someone else to do it, and I learned a lot too. Thanks for the help PJmax!
 
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Old 02-14-13, 07:47 PM
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You are very welcome and thanks for stopping back with the update
 
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Old 02-15-13, 03:27 PM
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I'm guessing the repair guy is figuring a $150 cost for the part and $850 to install it --- a half hour of work, probably.

Read more: http://www.doityourself.com/forum/gas-oil-home-heating-furnaces/488439-furnace-lights-intermittently-but-its-not-hot-surface-ignitor.html#ixzz2L0soEb5D>>



Pigs get NOTHING!



I was a furnace repairman, and I typically charged an extra $100 on a $150 part if I had it with me --- probably $200 or so if I hasd to shop for a part I didn;t haver and return to install it.

But really. Some people think their skill is a license to rip people off.

All too many people.
 
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Old 02-17-13, 07:26 AM
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I'm guessing the repair guy is figuring a $150 cost for the part and $850 to install it --- a half hour of work, probably.
He obviously wants to sell you a new furnace.
 

Last edited by hvactechfw; 02-17-13 at 09:01 AM.
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