Furnace Ignitor Intermittently Fails To Energize

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Hi All,
I've been having an issue with a Miller cmf-65 gas furnace with direct igni tion.
Normally the thermostat clicks on, after a few seconds I hear a click, indu cer motor comes on, the ignitor glows. After about a minute the gas ignites and then blower comes on.
When the ignitor fails to energize I don't hear a click and the inducer mot or keeps running. Turning the furnace off and on, either by the thermostat or the door restarts the furnace, no problem. There's no pattern to it - it 'll go for a week just fine, then 2 days in a row it fails...The problem se ems to be getting worse tho, needing more resets since I first noticed last winter.
I replaced the ignitor since it was old anyways, but the issue still remain s. Could it be an intermittent problem with the Ignition Control Module no t sending power to the ignitor? It's a older model Honeywell S89C1087, no L ED.
Any suggestions would be appreciated!
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On Friday, January 16, 2015 at 6:06:43 AM UTC-6, snipped-for-privacy@gmail.com wrote:

nition.

ducer motor comes on, the ignitor glows. After about a minute the gas ignit es and then blower comes on.

otor keeps running. Turning the furnace off and on, either by the thermosta t or the door restarts the furnace, no problem. There's no pattern to it - it'll go for a week just fine, then 2 days in a row it fails...The problem seems to be getting worse tho, needing more resets since I first noticed la st winter.

ins. Could it be an intermittent problem with the Ignition Control Module not sending power to the ignitor? It's a older model Honeywell S89C1087, no LED.

Have you checked: inside and outside for crap in the intake and exhaust? Is condensate draining properly? If so, it may be the vacuum switch or the co ntrol board. It's common for circuit board solder to crack and give you an intermittent problem. (Mine had a crack on the blower relay-not handy in th e middle of winter) Good luck!
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On Friday, January 16, 2015 at 8:51:33 AM UTC-5, bob_villa wrote:

ignition.

inducer motor comes on, the ignitor glows. After about a minute the gas ign ites and then blower comes on.

motor keeps running. Turning the furnace off and on, either by the thermos tat or the door restarts the furnace, no problem. There's no pattern to it - it'll go for a week just fine, then 2 days in a row it fails...The proble m seems to be getting worse tho, needing more resets since I first noticed last winter.

mains. Could it be an intermittent problem with the Ignition Control Modul e not sending power to the ignitor? It's a older model Honeywell S89C1087, no LED.

Is condensate draining properly?
Agree, it could be a safety not allowing it to proceed to ignition.
If so, it may be the vacuum switch or the control board. It's common for ci rcuit board solder to crack and give you an intermittent problem. (Mine had a crack on the blower relay-not handy in the middle of winter) Good luck!
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On Friday, January 16, 2015 at 8:54:36 AM UTC-5, trader_4 wrote:

e:

t ignition.

, inducer motor comes on, the ignitor glows. After about a minute the gas i gnites and then blower comes on.

er motor keeps running. Turning the furnace off and on, either by the therm ostat or the door restarts the furnace, no problem. There's no pattern to i t - it'll go for a week just fine, then 2 days in a row it fails...The prob lem seems to be getting worse tho, needing more resets since I first notice d last winter.

remains. Could it be an intermittent problem with the Ignition Control Mod ule not sending power to the ignitor? It's a older model Honeywell S89C1087 , no LED.

? Is condensate draining properly?

circuit board solder to crack and give you an intermittent problem. (Mine h ad a crack on the blower relay-not handy in the middle of winter) Good luck !
I found the manual for the furnace and the Ignition Module - I've been foll owing their flowchart and it gives a few reasons that the ignitor does not heat up - the wiring, the ignitor, or the S89c Cntrl Module.
I don't believe it goes into "lockout mode", It just looks like it's waitin g for the next instructions - as the inducer motor keeps running.
Bob : The furnace looks dry and clean inside, but also not sure where to lo ok. Wouldn't the the Control Module at least power up the ignitor to check for other errors? I see a motor relay, transformer, and time delay relay i n the elecrical box , don't see a vacuum switch. If I open up the electrica l box would I see a crack if there is one?
Tony : It's HSI, and reading up on it online it's a part that has a limited life and it's quite possible it's way beyond that. Vibrations from years o f use and hot/cold cycles could def cause loose soldier.
Should replacing the S89c with the modern equivalent be the next step then? The new one has LED to also narrow down other problems if they exist.
THANKS!
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On Friday, January 16, 2015 at 10:06:03 AM UTC-5, snipped-for-privacy@gmail.com wrote:

ote:

ect ignition.

ck, inducer motor comes on, the ignitor glows. After about a minute the gas ignites and then blower comes on.

ucer motor keeps running. Turning the furnace off and on, either by the the rmostat or the door restarts the furnace, no problem. There's no pattern to it - it'll go for a week just fine, then 2 days in a row it fails...The pr oblem seems to be getting worse tho, needing more resets since I first noti ced last winter.

l remains. Could it be an intermittent problem with the Ignition Control M odule not sending power to the ignitor? It's a older model Honeywell S89C10 87, no LED.

st? Is condensate draining properly?

r circuit board solder to crack and give you an intermittent problem. (Mine had a crack on the blower relay-not handy in the middle of winter) Good lu ck!

llowing their flowchart and it gives a few reasons that the ignitor does no t heat up - the wiring, the ignitor, or the S89c Cntrl Module.

ing for the next instructions - as the inducer motor keeps running.

look. Wouldn't the the Control Module at least power up the ignitor to chec k for other errors? I see a motor relay, transformer, and time delay relay in the elecrical box , don't see a vacuum switch. If I open up the electri cal box would I see a crack if there is one?

ed life and it's quite possible it's way beyond that. Vibrations from years of use and hot/cold cycles could def cause loose soldier.

n? The new one has LED to also narrow down other problems if they exist.

From the manual... On call for heat, the thermostat contacts close which en ergizes the combustion blower motor relax and starts the blower motor (I se e now blower=inducer).
When motor operation reaches 80% of full rpm, the centrifugal switch, locat ed in the motor end cap, closes and powers the time delay relay. The time d elay relay provides 30-60 sec prepurge cycle before supplying power the s89 c.
When s89c is powered, the ignition sequence is started with an internal saf e start check. After the check is complete , the s89c will initiate a timed igniter warm up period.
That clears a few things up but also seems to make diagnostic more difficul t! Damn intermittent problems!
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On Friday, January 16, 2015 at 9:06:03 AM UTC-6, snipped-for-privacy@gmail.com wrote: Regarding the circuit board...you would almost need to remove it completely and examine it under a light to look for cracks or burn/arcing areas.
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On Friday, January 16, 2015 at 11:16:30 AM UTC-5, bob_villa wrote:

Thanks Bob, I'm looking inside and I still don't see anything that looks like that, nor is that part listed anywhere in the manual - Here's a parts list, page 5
http://yaunco.com/pdfs/miller/cmfparts.pdf
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On Friday, January 16, 2015 at 10:44:15 AM UTC-6, snipped-for-privacy@gmail.com wrote:

Page 5, Item #6 HSI Control...can that be opened to check the board?
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Thanks Tony,
I see something called a time delay relay inside the electrical box , - reading up on it , it connects power to the elements over a period of 30-60 secs...maybe the s89 cntrl module isnt getting power because of an intermittent fault with the relay?
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Thanks Tony,
I see something called a time delay relay inside the electrical box , - re ading up on it , it connects power to the elements over a period of 30-60 s ecs...maybe the s89 cntrl module isnt getting power because of an intermit tent fault with the relay?
the Hsi control doesn't look like it supposed to be serviced, and the manua l says it connot be repaired - but its attached i cant see if there are scr ews or clips holding the cover on from underneath..Yes it would beneficial to see if there is a yvisible cracked or damaged connection.
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snipped-for-privacy@gmail.com wrote:

Hi, They seem to use non usual nomenclature for parts. item #16 on IPB(illustrated parts breakdown) called air tube. Can you locate it?
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Tony, that's not my model - check page 5, direct ignition gas burners for power gas models..
There are 2 relays left out of the diagram - in the electric box , the time delay relay and the motor relay .
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snipped-for-privacy@gmail.com wrote:

Hi, They call it pressure switch. Try Googling Nordyne furnace pressure switch. Any thing like that around inducer motor? The switch is NO type. Closes when pressure is sensed. It can get stuck open or closed.
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I 'm reading up on the "centrifugal relay", - it looks like it serves the same purpose as the pressure sensor- and it's at the base of the inducer motor, inside.
I don't think it's a servicable part, it might be part of the motor, which would mean replacement.
Still taking suggestions!
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snipped-for-privacy@gmail.com wrote:

Hi, If that is the case it is very poor design. Motor turning can't guarantee right pressure. What if turbine is loose on the motor shaft? Cenrifugal relay is not really a relay(coil. actuator, contacts) it is just a contacts which closes when motor spins up to full speed against a spring tension. Contacts can burn or get pitted making poor contacts causing intermittent problem. You can burnish the contacts some times to make it work again.
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On 1/16/2015 8:51 AM, bob_villa wrote:

in the intake and exhaust? Is condensate draining properly? If so, it may be the vacuum switch or the control board. It's common for circuit board solder to crack and give you an intermittent problem. (Mine had a crack on the blower relay- not handy in the middle of winter) Good luck!

One time I had a similar problem at a customer's furnace. Turns out the installer had not used the larger pipe required for the distance and number of elbows.
- . Christopher A. Young learn more about Jesus . www.lds.org . .
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On Friday, January 16, 2015 at 9:22:57 AM UTC-5, Stormin Mormon wrote:

This brings us to a related issue. Almost all the direct vent pipes I've seen, there is no screen guard, anything over them. Wasps for example could get in during summer. Or worse, rodents. For my Rheem, the install manual specifically says no screen, etc is allowed. I think they are worried about freezing rain, snow, etc blocking it. But that leaves a direct path into the furnace for mice, etc. On either the combustion side, or the fresh air side. Doesn't sound like a great idea.
And you're right about the pipe size versus distance, number of elbows, etc. On mine, I knew that it required 3" because it was 120K BTU. If I had thought about how much more difficult it is to work with, hang, align those, I would have gone down to a 100K which uses 2". It was a real bitch making all the tight turns, getting it to the exact spot it needed to go, etc.
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snipped-for-privacy@gmail.com wrote:

Hi, What kinda ignitor? HSI or Piezo? Loose circuit from cold solder or cracked solder joint on the control board or it is bad. If it is module only way is to replace it and see.
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snipped-for-privacy@gmail.com wrote:

Hi, After inducer motor starts the inducer pressure sensor should make to let ignition occur. The sensor is diaphragm type connected with small ttubing which often get dirty inside with debris. You should make sure thi tube is clean inside. After pressure is sensed OK, next step is ignition and flame sensor is next .... I'd check the pressure sensor. Find it around the inducer motor.
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On Friday, January 16, 2015 at 10:26:09 AM UTC-5, Tony Hwang wrote:

ignition.

inducer motor comes on, the ignitor glows. After about a minute the gas ign ites and then blower comes on.

motor keeps running. Turning the furnace off and on, either by the thermos tat or the door restarts the furnace, no problem. There's no pattern to it - it'll go for a week just fine, then 2 days in a row it fails...The proble m seems to be getting worse tho, needing more resets since I first noticed last winter.

mains. Could it be an intermittent problem with the Ignition Control Modul e not sending power to the ignitor? It's a older model Honeywell S89C1087, no LED.

I don't see anything that looks like that, or see anything that refers to a pressure switch in the manual...Could it be called something else, or mayb e I don't have one?
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