Nordyne/Miller CMF80-PO

[HowieH]

I have a Nordyne Miller CMF80-PO, also on the label is PGB-2-D1. It has a very intermittent problem of not lighting. The tech was out here yesterday and of course it was running and he checked a few things with his meter and said he couldn't fix anything that wasn't broken, and to call him again when it wouldn't light. So this morning I get up, and it's 58 degrees in the house and I call him and he's on his way up. Is there anything I should ask him to specifically check while he's here? I have a feeling when he opens the door, and and then holds in the safety switch that's hooked up to the door the damn thing is going to relight again and he won't find anything again. Thanks, Howie

UPDATE: The techs were here today, they replaced the transformer, and ignition module and the friggin thing still doesn't work . What I did this evening was when the igniter glowed and the valve opened (ROBERTSHAW 7000ADERC) the flame would stay lit for a few seconds then turn off, The next time it tried to light I lightly tapped the valve with a screwdriver and it stayed lit. Don't know for how long it will work. Hopefully all night cause it's 14* out now. Thanks and any and all help would be appreciated. Howie

[Robert]

Hi Howie,

Why did they replace those items ? If they were not the problem, they should not have replaced them.



Four things to cover:

1- Electrical- Make sure all electrical components in ignition circuit receive full power at appropriate times and hold for time designed to.

2- Make sure correct manifold gas pressure through burner for ignition process.


3- Make sure you have adequate combustion air.


4- Make sure that your ventilation (flue,roofjack,etc...) is correct and undamaged.



3 and 4 are basicly black and white, no intermittant.


So, that leaves 1 and 2.


You or they can locate last point of measured power (test point) in ignition circuit, then when it happens , immediately test for full power there.


If not present, problem lies downstream in elect. ignition circuit.


If it is present, problem most likely lies in gas not reaching ignition point in satisfactory ammount or at designed pressure.




Thanks,
Robert

[HowieH]

Well they finally made it back and as instructed they removed all the new parts they put on and reinstalled the old (2 yrs) ones again. Then they replaced some sort of relay, looked double stacked with 4 electrical connections on it. (I don't see one on your site) that sat under the ignition module in a box with the transformer. They did check out the pressures of the gas and they claim they are all good. Now it ran good for approx. 24 hours and all of a sudden nothing again. I reset it and tap on the valve and it fires up fine. I had asked him why it works when I tap it and he thought that the tapping vibrated that relay and made it work, but now it's a new relay. I'm leaning toward maybe something in the orifice? I'm just not sure if I want to pull that out or what.

[Robert]

Follow steps I listed and what to do when it happens to find the fault.


Make sure power is at end of circuit before going the gas pressure (orifice is part of that) route.


Thanks,
Robert

[HowieH]

Robert, Thanks for the help. I believe the part he replaced the last time was a Time Delay Relay, and like I said it worked for about 24 hours, then I reset it and it's been working fine since. I think what I'm going to do is pull the igniter out and check that and the orifice to see if anything is in there. Here's a pic of the burner. Where I have that yellow arrow, is that just pressed fit into the valve? Thanks again, Howie



EDIT: Answered my own question. I took it apart, the igniter is good and nothing in the orifice or the tube.

[Robert]

It's threaded.


Thanks,
Robert

[HowieH]

OK, got that figured out. The igniter looks fine and I assume that also works as the flame sensor. Nothing in the gas tube or orifice. The voltage when the valve turns on is 22-23.

[Robert]

If there isn't a remote sensor, don't believe there is, but didn't look it up.


Make sure it has correct power first.

Then check for gas flow.

Then combustion air.


Needs those and they must remain.


Is it NOT lighting or lighting then going out ?


Thanks,
Robert

[HowieH]

It lights, stays on for 3 to 5 seconds then goes out... What should the voltage be at the valve when all is working correctly?

[Robert]

24-28vac.


Could be ignitor not sensing flame.



That's a pricey guess though.



Thanks,
Robert

[HowieH]

24-28vac.


Could be igniter not sensing flame.



That's a pricey guess though.

Is 22 to 23 volts enough then?

What igniter does this beast take?? Do you stock them?

Thanks for all your time. Especially on a Sunday evening. Howie

[Robert]

Hi Howie,

You're very welcome, happy to help.


No, should be at least 23 always, but really should be 24.


I would replace transformer also.


Hot Surface Ignitor # 902499 @ $41.00


Transformer # 620825 @ $15.95


Both can be seen and ordered from left side through PayPal here:

http://www.mobilehomerepair.com/NordyneGas.html


Let me know if outside the U.S., added ordering info needed.


Can't gaurantee this will take care of it, but it is a good possibility and the 22-23volts is not enough from transformer.


Thanks for inquiring,
Robert

[HowieH]

I believe they replaced the transformer when they replaced everything else. When they removed those parts I don't know if they also removed the transformer. But anyway the transformer should be putting out between 24 and 28 volts, and it's not. So I guess I'll try the new transformer and igniter. Thanks again, Howie

[Robert]

Hi Howie,

The very lowest would be 23vac and it would have to stay ther always, never going below that.

Still may not be enough though as it should be 24+.


Hopefully one or both will take care of it.



Take care and best wishes,
Robert