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Jack11j · Jan 7, 2009, 12:22 PM

Our Miller model won't light up - intermittently. Came home to a 45 degree house and service call resulted in new electronic module and igniter. Next day same problem. Different tech - couldn't fix it, but suggested buying an oil burner! Has happened twice since, and was able to start by turning 'stat down to 55 and up again.
3 flashes on the module says: "gas valve error; false flame sensed during warm-up; control will return to normal oper. and repeat ignition when false flame is not present."
Checked forced draft fan, amps OK at .8. [The tech. tried to sell me a new draft fan!]
I haven't a clue! I'm afraid to leave the house for more than a couple of hours.

hvac1000 · Jan 7, 2009, 02:30 PM

Originally Posted by Jack11j

Our Miller model won't light up - intermittently. Came home to a 45 degree house and service call resulted in new electronic module and igniter. Next day same problem. Different tech - couldn't fix it, but suggested buying an oil burner! Has happened twice since, and was able to start by turning 'stat down to 55 and up again.
3 flashes on the module says: "gas valve error; false flame sensed during warm-up; control will return to normal oper. and repeat ignition when false flame is not present."
Checked forced draft fan, amps OK at .8. [The tech. tried to sell me a new draft fan!]
I haven't a clue! I'm afraid to leave the house for more than a couple of hours.

You might try cleaning the flame sensor.

Jack11j · Jan 8, 2009, 08:29 AM

Originally Posted by Jack11j

Our Miller model won't light up - intermittently. Came home to a 45 degree house and service call resulted in new electronic module and igniter. Next day same problem. Different tech - couldn't fix it, but suggested buying an oil burner! Has happened twice since, and was able to start by turning 'stat down to 55 and up again.
3 flashes on the module says: "gas valve error; false flame sensed during warm-up; control will return to normal oper. and repeat ignition when false flame is not present."
Checked forced draft fan, amps OK at .8. [The tech. tried to sell me a new draft fan!]
I haven't a clue! I'm afraid to leave the house for more than a couple of hours.

ADDITIONAL INFO ON PROBLEM: Gas pressure within specs; there is no flame sensor in the firebox, and no connector on the control box. Good suggestion from HVAC1000, but not for a Miller MMHB. BTW, how come Miller doesn't even list a MMHB - they all are M1HB on their webpage. Can't contact Miller.
Ideas?

hvac1000 · Jan 8, 2009, 11:23 AM

ADDITIONAL INFO ON PROBLEM: Gas pressure within specs; there is no flame sensor in the firebox, and no connector on the control box. Good suggestion from HVAC1000, but not for a Miller MMHB. BTW, how come Miller doesn't even list a MMHB - they all are M1HB on their webpage. Can't contact Miller.

EXACT brand and model of module?

You must be smarter than me since my book on the unit says it has a flame sensor!

Jack11j · Jan 8, 2009, 07:11 PM

Originally Posted by hvac1000

ADDITIONAL INFO ON PROBLEM: Gas pressure within specs; there is no flame sensor in the firebox, and no connector on the control box. Good suggestion from HVAC1000, but not for a Miller MMHB. BTW, how come Miller doesn't even list a MMHB - they all are M1HB on their webpage. Can't contact Miller.

EXACT brand and model of module?

You must be smarter than me since my book on the unit says it has a flame sensor!

Let me re-phrase that! What I see in the comb chamber is a gas orifice unit [hey, I don't know what it's called]:) and the igniter, which has two wires going to it. It looks like a woven wire cylinder 2" long, with a porcelin[?] center. Can this unit be both igniter and flame sensor?
It's a new "UT Electronic Controls, 1018 Hot Surface Ignition" which the local gas guy replaced.

hvac1000 · Jan 8, 2009, 07:17 PM

Does it look like this

hvac1000 · Jan 8, 2009, 07:19 PM

Better pic

hvac1000 · Jan 8, 2009, 07:21 PM

Is this what you were talking about with the two wires.

Jack11j · Jan 9, 2009, 06:40 AM

Yes, looks very much like it. The leads are about 16" long, as it goes from the module to the end of the "burner tube."

Jack11j · Jan 9, 2009, 06:41 AM

Originally Posted by hvac1000

Better pic

Yes, this is the unit.

hvac1000 · Jan 9, 2009, 08:37 AM

Try this diagram to help solve your problems with ignition. You should have some sort of flame sensor since that is a safety control. Usually the flame sensor is located near the burner around the same area as the hot surface ignitor. Now I still cannot locate your exact model of furnace as I do not have it in my electronic data base. I do have a 5 inch thick book on Nordyne/Miller somewhere buy in the library there is over 100 books in no specific order and I tried looking in the pile but no cigar. It is possible I lent it out and never got the book back. That happens all the time. LOL

There are many different UT Electronic moduals that have been used in different furnaces that is why I wanted to find the specific one for your unit. Some were wired different and some used a vacuum switch as a safety and a flame sensor so there can be differences.
One tip from your post
gas valve error; false flame sensed during warm-up; control will return to normal oper. and repeat ignition when false flame is not present."
False flame sensed means that the flame sensor is not working and that is why I told you to clean it your reply was that it did not have one so I have no idea which direction to go from here except to take a look at the link below and jump your unit through the steps provided.

Mobile Home Repair - Mobile Home Gas Furnace Operation Flow Chart

Jack11j · Jan 9, 2009, 09:45 AM

Originally Posted by hvac1000

Try this diagram to help solve your problems with ignition. You should have some sort of flame sensor since that is a safety control. Usually the flame sensor is located near the burner around the same area as the hot surface ignitor. Now I still cannot locate your exact model of furnace as I do not have it in my electronic data base. I do have a 5 inch thick book on Nordyne/Miller somewhere buy in the library there is over 100 books in no specific order and i tried looking in the pile but no cigar. It is possible I lent it out and never got the book back. That happens all the time. LOL

There are many different UT Electronic moduals that have been used in different furnaces that is why I wanted to find the specific one for your unit. Some were wired different and some used a vacuum switch as a safety and a flame sensor so there can be differences.
One tip from your post
gas valve error; false flame sensed during warm-up; control will return to normal oper. and repeat ignition when false flame is not present."
False flame sensed means that the flame sensor is not working and that is why I told you to clean it your reply was that it did not have one so I have no idea which direction to go from here except to take a look at the link below and jump your unit through the steps provided.

Mobile Home Repair - Mobile Home Gas Furnace Operation Flow Chart

Thank you for your diligence in trying to solve the problem.
I used the flow chart and where it says to call a technician, that has been part of the problem: 4 techs have been here 5 times and after replacing igniter and control module, the problem still exists! Amazing.
BTW, www.askmehelpdesk.com is an excellent site.
Thanks again.
Jack in Pennsylvania

hvac1000 · Jan 9, 2009, 03:02 PM

That is one of the frustrations of trying to do a repair sitting behind a computer. If I had my tool kit/meter bag and was actually there it would be fixed by now. I have a feeling that something was changed on that unit and the work was done incorrectly. That in turn has lead everyone else astray and without the original furnace manual all is guess work. I will keep looking around and if I can find the book I am looking for I will post back on this link. Good luck and sorry I could not help.

In the mean time some of this might work.

slowwalker · Dec 8, 2010, 02:55 AM

I have the same problem with no flame sensor. Mine is a Miller CMF 80 PG CONV about 5 years old.

Owen Sclandersa · Aug 9, 2012, 04:35 AM

Looking for a wiring diagram when used in agriculture heater

bigdaddy31674 · Oct 13, 2012, 09:32 AM

I have a similar furnace in my home and experienced the same problem. There are three elements of fire; Fuel, air, and spark. If the flame is igniting, its getting spark(or glow plug style ignitor). If the flame doesn't last or gets weak it is losing air or fuel. Your model has a combination ignitor/flame sensor. Most likely, with your model , it's not losing fuel, it's probably not getting enough air. Watch the flame through the peephole and see what the flame is doing. If you see blue then orange then blue then out, you are most likely losing air. Remove the inducer motor, 5 bolts including the ground wire. You'll want to remove the ground wire and disconnect motor so you can completely remove motor and squirrel cage. Check for debris in the squirrel cage or obstruction in the duct above the motor. When I removed the motor and squirrel cage on my furnace I found a dead bird wedged in the duct just above the motor restricting air flow. Works like new now.

live2ride74 · Oct 18, 2013, 02:51 PM

I have had a similar situation recently. What I have found is that the adjustment on the inducer fan was too far open. After moving to the next lower size on the air flow gauge my furnace is working perfectly. Now instead of the furnace bouncing off the high limit switch the old girl is running off the thermostat. This is after following all the advice I have read in this posting... the cleaning of the intake duct, burner, and exhaust outlet. I DID NOT NEED TO REPLACE ONE SINGLE PART! Cheers.