Cleaning Miller CMF

Robert_H

A recent Miller CMF-80 I serviced had a lot rust and flakes on top of the heat exchanger as seen with the roof jack raised. I used a soot snake on my vac and got everything off the top but am concerned about what might have fallen around the sides.

I would like to go back and clean deeper. Has anyone here ever removed the top or front to clean one of these?

Also, I believe the debris is from the old roof jack that was replaced a last year. other than this the furnace is in really nice shape.

Thanks

Robert

EBEBRATT-Ed

I haven't done one in a long time so not much help. Usually have to find a smaller hose and duct tape it onto your vac hose.

EBEBRATT-Ed

Nordyne (now called NORTEK) bought out Miller. They are tough to get information out of them sometimes but they may have some cleaning instructions.

Unfortunately, those furnaces don't have a great reputation but in a trailer, you are kind of locked in to what you have.

HydronicMike

I use a 3+ ft. piece of garden hose instead of the metal snake. Just slide it into the main hose nozzle. Holding your gloved hand there gives you enough of a seal.

EdTheHeaterMan

You need the gasket for the front door where you remove the burner the jacket panel and the combustion chamber cover. Carefully lift the combustion chamber out of the heat exchanger and then use your soot vac's thin metal flex hose to suck soot from behind the baffle that holds the combustion chamber in place….

This exploded parts view shows the heat exchanger (HX) and the parts of the jacket and HX that you need to remove to access the area that never gets cleaned.

Below is a detail of the HX front and side view that indicates the path of the heated exhaust gasses thru the HX in RED. The combustion chamber that needs to be removed is shown in the side view on the left and the baffle that is behind the chamber that needs to get soot vacuumed. the problem area with debris is shown in brown. It is tough to illustrate but this is the best I could do.

I only had to do this 2 times in my 40+ years of service calls… and I have services hundreds of Miller CMF 80 furnaces in my time.

I hope you don't need to do this but if there is a lot of back pressure in the peep hole for viewing the flame, then first . . . check that the roof Jack (that is the chimney section that goes thru the roof) cap has not been smashed down on the vertical pipe blocking off the exhaust opening. Hate to see you go thru all that work only to find that you can fix it is 5 minutes by removing the roof cap. Hence the tag line in my signature.