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Troubleshooting a Miller Oil Furnace

Posted by timsrv (My Page) on
Sat, Dec 23, 06 at 2:22

Hi, I got a call from a cold tennant tonight. Since I can't seem to get a serviceman out to his location (due to the holidays), I'll be driving 3 hrs tomorrow to try and fix his furnace. It's a Miller CMF80-PO oil burning furnace. After having a conversation with him on the phone, I was able to extract the following information. Tuning the wall t-stat up causes a click in the lower motor (probably a relay for the pump), but nothing else happens. He can get the blower fan to come on by messing with a manual reset button, but blows only cold air. I was hoping someone here may be familiar with troubleshooting this thing and could give me a few pointers. It would be nice to know sequence of events for start-up and voltages I should see in key places. Any help or pointers would be greatly appreciated. Thanks in advance. Tim


Follow-Up Postings:

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RE: Troubleshooting a Miller Oil Furnace

timsrv
If you do not completely understand my explanation or not aquainted with oil furnaces do not try to fix it ,call a tech. The tstat calls for heat energizing the primary control. The burner motor and transformer will be brought to life.The transformer carries 10,000 volts to the electrodes and will put you on your can. The burner motor is coupled to the oil pump and delivers oil to the nozzel at the same time electricity is sent down the electrodes to the end of the drawer assembly where the fuel and spark meet causing combustion. After the unit heats up the main blower is activated ,delivering heated air to the trailer.
Be careful


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RE: Troubleshooting a Miller Oil Furnace

I've been there.
This site is a treasure trove for the theory and practical advice.
http://oiltechtalk.com/Oil_Tech_Talk_Toolbox/Old_Files.htm
Give 'er a try.
Good luck.
-br


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RE: Troubleshooting a Miller Oil Furnace

Boltonranger, thanks for the info and link. I checked the site you mention, but didn't find anything on Miller. Do all these things basically have the same sequence of events / voltage values, or are there differences that will effect my troubleshooting?

Turnkey I appreciate info and your concern. No worries though as I am a master certified RV technician by trade & run my own business repairing RV appliances (which I think have similarities). My tenant couldn't find a schematic on the unit, so that worries me slightly. If I find one when I get there, then there shouldn't be a problem. By the way, this furnace isn't in a trailer. It's about 10 years old and in a 900 sq ft 2 bdrm home. The house is almost 100 years old! I'll be leaving in a few minutes. It will take about 3 hrs to get there. If he has an internet connection, I'll check back when I get there. Wish me luck! Tim


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RE: Troubleshooting a Miller Oil Furnace

I wonder what he's gonna do if he gets out there and finds a bad primary control or siezed burner motor. hmmmmm


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RE: Troubleshooting a Miller Oil Furnace

Actually, based on what my tenant told me, I'm suspecting a seized burner motor. Although not able to get a serviceman out there, I was lucky enough to contact one in the area. He said he has a good inventory for parts to this unit and would sell me parts (I just have to use a secret phone ring combination and he will answer :). I'm leaving now. Thanks again. Tim


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RE: Troubleshooting a Miller Oil Furnace

Are you sure he just isn't out of oil ?


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RE: Troubleshooting a Miller Oil Furnace

Boy kalining, that would be a real kick in the a-- huh? I could see the headline in the paper now, "LANDLORD TRAVELS 3 HOURS TO REPAIR FURNACE AND ENDS UP STRANGLING TENNANT" LOL Actually, he mentioned something earlier about a click coming from the burner. Probably the cad cell relay. We'll just have to wait and see if he's got 110 VAC between those orange and white wires under there.


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RE: Troubleshooting a Miller Oil Furnace

Timsrv, my mistake. Ithought it was probably in a 14 x 70 3 bedroom trailer not a doublewide. The RV industry and your tennant house do have similarities, they both get to where they are going on wheels. Could not help myself, good luck


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RE: Troubleshooting a Miller Oil Furnace

Howz that old saying go? In some parts of the south there's a big similarity between a divorce and a tornado. In either one "somebody" is gonna loose a trailer! LOL


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RE: Troubleshooting a Miller Oil Furnace

LOL, I just got back and I'm happy to announce my Tenant is warm and happy now. By the way, this unit is not a mobile, It's a 100 year old 2 bdrm house (built from lumber on location).

As for the furnace, it really wasn't too difficult to troubleshoot. I think the fear of the unkown is often the worst part when working on something unfamiliar. Once I pulled the cover off the primary control everything was self explanatory (didn't even need a schematic). The problem turned out to be a bad primary control. There was a cold solder joint where the relay attaches to the board. It somehow made it that way for the past 10 years, but finally gave up. I could have re-soldered, but opted to replace. Probably paid too much ($146 with tax), but my time is worth something & I didn't want to go back anytime soon. Now I've got to get up and walk around a bit (I've been sitting on my can driving for the better part of the day). Thanks for the help everybody! Tim


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RE: Troubleshooting a Miller Oil Furnace

Glad to hear it Tim;
That money's not so bad on short notice.
Merry Christmas.
-br


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RE: Troubleshooting a Miller Oil Furnace

Glad to hear it was an easy one tim, and the trip was uneventful. I hope that tennant realizes what a good landlord he has. If it was me I woulda said, "hey, nobody made you move to a cold region of the country" LOL BTW, just where is it where heating technicians don't work on holidays anyway? Hows the real estate market out there where that is?


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RE: Troubleshooting a Miller Oil Furnace

Thanks for asking. Trust me, you don't want to live there. It's in Hoquiam WA, a depressed coastal timber town (just far enough away from the beaches so that tourists don't stop there). The climate is mild as far as temp goes, but it rains all the damn time. Real estate market sucked when I bought that house 9 years ago and still sucks now. Nobody has jobs and everybody is broke. At least I got out :). I'm much happier living in SW WA (just a few miles north of Portland OR). It's amazing how much nicer the weather is here. The real estate market here is booming too. The house I live in has gone up in value 50% per year (since I purchased 2 years ago). There is a bunch of new construction (residential, schools, businesses) in my immediate area & so far I've been immune to the housing bubble. Let's just hope that continues for a while. Tim


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RE: Troubleshooting a Miller Oil Furnace

Sounds nice,I like your line of work too. You must meet alot of interesting people from all over the country servicing RV equipment.


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RE: Troubleshooting a Miller Oil Furnace

Yes, I am very lucky. I really enjoy what I do as well! Here are some of my "on the job" pix. Tim

http://www.TimsRV.net/photos.html

Here is a link that might be useful: My web site home page


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RE: Troubleshooting a Miller Oil Furnace

Looks like a pretty decent gig tim. Now just think, if they every devise a way to run oil fired furnaces in motorhomes you'll be a pioneer in that aspect of the industry too. :-) Why don't you let these folks in on the simple fix for most of the problems with those little absorber refrigerators. Nah, that would be like giving away business for free right?


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RE: Troubleshooting a Miller Oil Furnace

No simple fixes for a rusted out cooling core. Actually the biggest problem with absorption refrigerators these days is planned obsolescence. Around 1980, they improved the design to prevent damage if ran off-level. Unfortunately, at the same time they quit galvanizing the pipes inside the foam pack.

As long as you didn't run them off-level, the older refers would easily last 20+ years (I still see them from the early 60's that are still working great). The biggest problem with a refer that lasts so long is it tends to get kind of gross inside over the years. I guess we don't need to worry about that anymore as the average life span for a cooling core now is only 10 - 12 years. Reasonable cost of replacing a full size RV refer ranges from $1,400 - $1,700 (conventional type) & up to $3,500 for side-by-side units. There are companies that "recondition" these cores, but it's been my experience that these only last 2 - 4 years. Based on cost and longevity of reconditioned VS new, I no longer recommend core replacement. Tim

PS: I hope you guys aren't too strict here about getting off topic. If so, then I apologize. Tim


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RE: Troubleshooting a Miller Oil Furnace

Hey you guys seem to have something under the hat. Can someone tell me the cause for the mis-fireing of my Miller Kerosene Furnace? Thanks in advance. John


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RE: Troubleshooting a Miller Oil Furnace

Not to be offensive but how the hell are we supposed to do
that? you give no info on anything. i'll ask you how long is a piece of string ? It will misfire if you are tring to
burn motor oil. It will misfire if there is no ignition.
It will misfire if there is no fuel. Get real. no one can
answer that without some history on your unit. Does it not
fire cold ? does it not fire hot ? does it not fire after a
heating cycle ?


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RE: Troubleshooting a Miller Oil Furnace

For cryin out loud kalining, you live in a mobile home up there in the great frozen north and you don't even know what makes a Miller Kerosene furnace mis fire!!! 99 times out of a hundred it's the flue damper bearings! Even I know that!


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RE: Troubleshooting a Miller Oil Furnace

Mr. Havac. i'll give you that one but what about the other
1 percent that no one EVER thought of ? It's guys like us that usually get stuck with the one percent. You might have
come across that ? I use an electric furnace with a wood stove. The electric furnace is the back up. I have this place tweeked up to where my phone bills are higher than my hydro bills but i'm working on that too. Good to hear
from you havac. Wondered what happened to you. Nothing new up here. Got a shight load of snow but nothing compared to north dakota.


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RE: Troubleshooting a Miller Oil Furnace

Hi My Miller gun furnace is blowing out Pure Kerosene smell and it is strong. I have done all the normal stuff like clean the filter, change the tip and bleed the furnace to get the air out. I do get a down draft but not to the extent that I should get this much fumes. What can I do to stop these fumes from being blown up my heater vents???


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RE: Troubleshooting a Miller Oil Furnace

I have a miller burner in my mobile home and I could use some help and the technician could use some help. I ahve a restart problem. On a freezing day I can turn the heat on and i fires up instantly and soon the blower comes on. The last time it ran for 2 1/2 hours before coming up to the minimum temperature on the thermostat. I was working on other things and noticed that the burner nevcer came on again and it was getting colder. I opened the door and had to reset the red buttun and when I close the door the burnet started instantly and ran until the called for temperature was reached. It repeated the problem and anever restarted even though the temperature dropped. I reset the red button and ran it again until it reached the called for temp and shut down. I thn put my ear to the furnace door and mover the thermostat up. The only thing I heard was I very very slight click and nothing else. When I opened the door the red button had tripped. The next day I went and reset the red button and the furnace fired up instantly. After about a minute or two the blower came on and blew heat into the mobile home. I then turned the thermostat off and the burner stopped right away but the blower continued for about 5 minutes. after the bloser stopped I turned the heat on at the thermostat and it ran OK. I did the same thing and got the same result. I did it again but after I turned off the thermostat and the burnr stoppd ad while the blower was still running I turned the thermostat on and it fired right away. It seems to only fail when the called for temp is reached and then there is a call for heat after the temp drops. The repairman replaced the transformer (Allandon ?)because he said they were problematic. Next he replaced the blower motor because he said the bearings were red hot and siezed. The problem continues exactly the same way. I could use some help to pass along to the repairman.
Tanks in advance.


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RE: Troubleshooting a Miller Oil Furnace

Not too funny. I am having the same problem. I too have had the service man here who said I need a new furnace??? I have already changed the control limit switch, thermostat,now he wants to replace the gaskets after he checks for holes in the burner. But before I let him do anything else I want to have him check my vent system for any holes where cold air can be sucked back. I tested the unit by starting it and using a hair blower on the thermostat this did the trick. so I know it is not the furnace. will update after vent check.


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RE: Troubleshooting a Miller Oil Furnace

Yes it was the vent. It had came undone causing a large amount of air to flow back into the system. once we repaired the vent the furnace worked just fine.A expensive lesson for a cheap repair. Had to repost under a different name as I was unable to sign back in with Andi


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RE: Troubleshooting a Miller Oil Furnace

I have a Miller furnace in my garage an older model when the temp in the garage gets below 32 degrees f the furnace won't fire up, when its aove 32 degres it fires up and works great I've checked with several people and they never heard of such a thing.


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RE: Troubleshooting a Miller Oil Furnace

a MILLER furnace CMF2 80 PO CONV FLASHING RESET BUTTON AFTER JUST ONE ATTEMPT TO RESET AND RESTART FURNACE. FLAME FOR SEVERAL SECONDS, THEN SHUT OFF, AND RESET LIGHT HAS CONTINUOUS FLASHING. ANY IDEAS?


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