The combustion chamber of the oil furnace

[@ryanbrandt3374]

On the miller Mobil home furnace when changing the firebox I’ve anal bolts in the past. I just bought a rivnut gun and was wonder if you have used one if so does the heat affect the rivnut over time?

[@brutusjb3814]

So all it does it protect the inside metal and it heats around the flame to help combust the particles the flame it self can't burn alone.

[@grayfurnaceman]

That's pretty much it. GFM

[@redmavis6136]

I will be replacing the combustion chamber on my Miller CMF80 furnace this year...the old one looks cracked and in bad shape after 30+ years of service. Looks very similar to the one shown in your video. I attempted this operation 10 years ago but snapped off one of the 14 nut/studs on the weld plate then, so I gave up...but this must happen even to technicians doing the job. Do you know if these heat exchanger studs can be replaced? I've found that Miller/Nordyne used to supply a stud replacement kit, but hard to find now. This furnace has served me well for many years if serviced regularly. I really appreciate all of your videos/knowledge...has helped me understand my furnace better. Thank you!

[@grayfurnaceman]

Not simple. As there are so many, I would not be concerned about one. Also, careful as you remove them. GFM

[@redmavis6136]

@@grayfurnaceman Thanks for the advice...yes, I'll have to be very patient removing the remaining nuts with probably a lot of penetrants and heat. Hopefully I won't have to resort to drilling or hammering on the exchanger as this thing is so old now!

[@ryanbrandt3374]

They have a tool called a rivnut gun. I just purchased it. I bought the ratcheting one for tight spaces. It will work but I don’t know how the heat will affect it over time. With the expansion of the steal. Might not do anything. But there on Amazon for 60 bucks. If it works well it will be worth every penny. I have a lot of millers out there

[@redmavis6136]

@@ryanbrandt3374 I would think the constant heat cycling would tend to loosen the rivnuts over time. Would you use the existing holes where the studs are located or drill additional holes?

[@ryanbrandt3374]

@@redmavis6136 use the existing holes. Prob would and some high temp silicone around the rivet as well. When I do try it I will check it every cleaning to see if they loosened up. Thanks for the info. I wouldn’t use it if they all snap though that’s to risky. Just put in a new thermonpride Mobil home. I love those. Not a fan of the new millers.

[@r9ball717]

I am replacing the combustion chamber on a Miller CMF-80-PO mobile home furnace, on the back of the inlet cover there is a flange with four holes, were the chamber butts up to. The old chamber was not attached just slide on the burned tube, is this the correct mounting or does it get bolted or wired ?????

[@grayfurnaceman]

I can't say for sure on that furnace but I have never see one installed with any connectors. GFM

[@mainelyelectric]

Hey another question about my miller furnace in my greenhouse. You say in this video that these combustion chambers should be glowing red when fully warmed up! But should I be seeing as it’s running and up to temp when I look into the inspection port at the top of this chamber what looks like a yellowish Hot gaseous plasma coming out of the top of the chamber?? If I’m describing it correctly. You have said in the past a few licking yellow flames 🔥 out the top is normal but that is not what I’m trying to describe. I’m thinking it might just be how the hot gases are roaring out of the top of the chamber and burning.

[@grayfurnaceman]

If you have a large amount of flame coming out of the combustion chamber, the chamber could be too small. GFM

[@mainelyelectric]

grayfurnaceman Hey Thanks as always for the reply, it’s the chamber that came in the furnace. And I only have a .579 nozzle installed and the pump pressure is set at about 130-135 psi since It seemed to run BEST and smooth at that pressure. I think what I am seeing is just the high heat and combustion roaring out the top of the chamber like normal. I don’t have very much flame 🔥 licking out of the chamber, a little lick of flame 🔥 hear and there but that’s normal. I will try to email you a picture but not sure if the camera will capture what I’m seeing.

[@trankt54155]

I have the one that stands up like a a half of the pyramid. Where would I get a replacement one in case if the one I have is broken. It is very soft and flimsy.

[@grayfurnaceman]

I don't have any sources. I would try a local dealer. GFM

[@mrokofsky]

Should the chamber liner completely enclose the flame? The flame can be seen slightly outside the inner liner but doesn't seem to be damaging the metal part of the chamber. Two people who have seen a photo tell me it means I need to have it replaced and two people with more experience tell me it's fine. Any thoughts?

[@grayfurnaceman]

It is normal for the flame lick out the top of the combustion chamber. If the chamber is cracked and flame is coming out the sides, the chamber needs to be replaced. GFM

[@mrokofsky]

grayfurnaceman is that an expensive job?

[@grayfurnaceman]

Depending on the furnace, $400 to 600. GFM

[@amandarowland7333]

Gary, I really need your help I have an old 1970 Mobile home with a Nordyne Miller CMF80 Beckett Oil Burner. How often should the combustion chamber be replace mine looks to be foam, and it look like it has a hole in the bottom of it.Can I change the combustion chamber liner or do I have to replace the entire heat exchange? By the way thank you for you're videos they have been a god send for my husband.

[@mainelyelectric]

Amanda Rowland The combustion chamber like this one in the video for Miller mobile home furnace’s is sold on amazon for around $40-60 I believe, I was researching them for a backup. They are not to hard to change they should just slide into place but be careful with them they are fragile and you should have a mask 😷 since they are a fibrous ceramic and not good to breath!

[@ckproper]

My combustion chamber has a crack in it visible through the flame inspection port. Should it be replaced?

[@grayfurnaceman]

I would replace it. GFM

[@HYDROGENTEK]

Where can I get a replacement chamber for a unit using a .75 gph nozzle. Mine is broken up which caused cracks on one side of the heat exchanger.

[@grayfurnaceman]

HYDROGENTEK If you have cracks in the heat exchanger, your least problem is the combustion chamber. You need at least a new heat exchanger, probably a new furnace. Don't even think about welding it. Hope this helps.GFM

[@ConSoul]

what happens in the combustion chamber cracks or breaks - is there a danger to the furnace?

[@grayfurnaceman]

Yes, If the flame touches the heat exchanger, it will burn thru it. GFM

[@donfreeman4736]

I'm not sure if this is normal, but there is a hole on the side of my chamber, it's located on the inspection door side of the furnace and it is a perfect circle. I'm not sure if this is by design or a burn through. My furnace is mounted horizontally in my basement. Do all chambers vent through the top? (this could be a confusing statement as different models do also operate both standing and laying down). I may have answered my own question? Btw..great videos, Furnace porn... love it!!

[@grayfurnaceman]

It is probably normal if it is at the exit end of the combustion chamber. GFM

[@donfreeman4736]

Yes, your right, the hole in question is pointed at the exhaust vent/pipe leading to the chimney. All your videos are done so well and approached in a manner that is easily understood. Thank you for taking the time to produce them. It really is appreciated.

[@grayfurnaceman]

Welcome GFM

[@Xbreaselx]

Was looking in an inspection hole last week and saw a cloth/canvas looking thing surrounding the flame.. What would that be?

[@grayfurnaceman]

Could be a part of the combustion chamber that is falling apart. GFM

[@HYDROGENTEK]

I planned on cutting the damaged area, making the cut as close as I can to the original welded seam and replace it with a similar gauge sheet metal.

[@grayfurnaceman]

HYDROGENTEK I won't support any welding of a heat exchanger. It is dangerous and I have never seen it work. They always seem to break next to the weld. Give up on it and go with new.GFM

[@Dicofol1]

How long do combustion chambers like these last ?

[@grayfurnaceman]

Unless they are physically damaged, they last for the life of the furnace. GFM

[@PracticalOutdoorist]

can you replace the liner? If so, with what?

[@grayfurnaceman]

Yes. If the old one is brick, a wet pack can cover it. If it is a foam liner, they can be purchased. GFM

[@MrGoddesslover]

do you have a video on replacing the chamber?

[@grayfurnaceman]

+Niclous Cone I have not done one. I will consider doing one. GFM

[@MrGoddesslover]

+grayfurnaceman if you could I would be great full