# Miller combustion chamber cleaning



## dneilson (Dec 13, 2009)

I have a Miller MSHA oil mobile home furnace. Have had a few service calls over the last month. New burner motor and solid state controls installed and still had problems. The cad cell gets very dirty and when cleaned furnace runs fine until it gets dirty again. They say the combustion chamber needs to be cleaned to correct this. They say to do this the furnace must be removed, moved to their facility, cleaned and re-installed. this of course would be extremely expensive. This doesn't make sense to me so my question is----is this true? The are also trying to sell me a new furnace. If anyone has a definate answer I would greatly appreciate it. Thank you.


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## beenthere (Oct 11, 2008)

Can be removed and replaced on site. Very seldom can you remove it, and clean it. without damaging it.

Also, once it is removed. The flue passage ways need to be cleaned. Thats where the soot really is. And you probably have a lot on the top of the furnace. Where the flue pipe connects. 

4 hours to do the whole job correctly, including inspecting the roof jack.


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## dneilson (Dec 13, 2009)

Thank you for the fast reply. Well, that's one question answered, they don't know it can be done on site--doesn't speak well for them. I just took a look at the top of the furnace at the flue pipe connection point and there's not one bit of soot on the top of the furnace anywhere. You say the chamber is easily damaged so if they do that they'll have to order a new one which is probably expensive--so--that coupled with the fact they don't seem to know what they're talking about it doesn't seem like a good option. I wonder if they misdiagnosed this--is there anything else that could cause the cad cell to dirty up? After they replaced the burner motor and installed the solid state controls it was good for about a month. Another thing they did was put a probe into the flame with a device they pumped on to pull stuff out and it deposited on a strip of white paper and it was absolutely clean. Not sure what to do, I'd really like to avoid buying a new furnace but if that's the best thing to do I guess I'll have to do it.

Thanks again!!


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## yuri (Nov 29, 2008)

Call another company with better techs. Beenthere is our oil guru :notworthy:and it sounds like it needs some serious attention. The cell rarely gets dirty unless the flame is dirty/poor combustion and that costs you extra fuel $$.


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## beenthere (Oct 11, 2008)

The combustion chamber is not really expensive.
Im my area, its a commonly stocked item. Lots of them get replaced on site when the furnace is cleaned.

You might want to call another company.

What you saw them use is a smoke tester. used to determine how clean it is burning.

Probably just clogged up in the passage ways.
And reducing your overfire draft. Which can cause soot to build up on teh cad cell.


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## dneilson (Dec 13, 2009)

Thanks for all the information, I'll have to give this some thought and decide what to do.

Thanks again!


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## dneilson (Dec 13, 2009)

I read the paper work the tech left after his last call and wonder if his comment might shed some more light on my real problem. He said "the flue draft goes anywhere from +2 to -.08". beenthere--you mentioned that it might just be clogged up flue passageways so I'm thinking maybe I can get them to do that and not have to bother with the combustion chamber. Any advice appreciated, am really trying to avoid buying a new furnace.


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## beenthere (Oct 11, 2008)

Only way to clean flue passage ways is to remove the combustion chamber.

If your flue drat(draft in flue pipe, not over fire draft)is going into positive draft. Check your chimney cap. It may have rusted out some, and have a hole in the top of it. The draft should not go to a positive draft.

Could be you have a bad roof jack.


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## dneilson (Dec 13, 2009)

OK--thanks for the additional information.


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## dneilson (Dec 13, 2009)

I just had another talk with a different guy at my service place. I got him to agree that the furnace does not have to be completely removed and taken to their place, cleaned and reinstalled. What he did say was that the chamber had to be removed and taken outside and cleaned with water. Is this correct? I forgot to ask and he didn't mention how they clean the flue passages. He said it would be a 4 to 5 hour job and be around $500. I'm still at a loss what to do.


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## beenthere (Oct 11, 2008)

Better to replace then try to clean the combustion chamber.
Wet, the chamber will be damaged by being handled.

4 hours for a really dirty unit. 

And if the guy has a lot of practice. A real dirty one can be done in 3 hours from pulling into the driveway to leaving the driveway.

To clean the passage ways. Besides sticking the snorkel up the passage ways. They should be using a hammer to knock the soot, loose. I know it sounds strange. but it works. Saves time and money.

Its not a cheap job. It doesn't take much in the way of parts.

1 combustion chamber, 2 gaskets, 1 nozzle(wouldn't trust your nozzle since its been subjected to heat).


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## dneilson (Dec 13, 2009)

Again I thank you for your expertise. It's been running fine since the last service call but I'm sure it's going to act up again. When it does I don't think I'll put any more money in it--will get a new one. They sell Thermo Pride and I've researched it and it looks good (the OMD-70). They want $2850, complete price for furnace and installation. $850 down and 0% financing for the remainder. That seems pretty decent unless someone says Thermo Pride is no good.

Thanks again!


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## beenthere (Oct 11, 2008)

Thermopride is probably the best made oil furnace you will find(dang things weigh a ton, their constructed that good).
It has the price tag fitting its quality. but is well worth the money.


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## dneilson (Dec 13, 2009)

Sure am glad to hear that. I don't think that price is horrible and it's hard to beat 0% financing.


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## beenthere (Oct 11, 2008)

dneilson said:


> it's hard to beat 0% financing.


0% is nice.


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## coachwert (Jan 9, 2010)

*what fuel is used*

What fuel are you useing. if you are useing diesel fuel this burns alot dirtier. and this can cause black suet all over, even the cad cell.








dneilson said:


> Thank you for the fast reply. Well, that's one question answered, they don't know it can be done on site--doesn't speak well for them. I just took a look at the top of the furnace at the flue pipe connection point and there's not one bit of soot on the top of the furnace anywhere. You say the chamber is easily damaged so if they do that they'll have to order a new one which is probably expensive--so--that coupled with the fact they don't seem to know what they're talking about it doesn't seem like a good option. I wonder if they misdiagnosed this--is there anything else that could cause the cad cell to dirty up? After they replaced the burner motor and installed the solid state controls it was good for about a month. Another thing they did was put a probe into the flame with a device they pumped on to pull stuff out and it deposited on a strip of white paper and it was absolutely clean. Not sure what to do, I'd really like to avoid buying a new furnace but if that's the best thing to do I guess I'll have to do it.
> 
> Thanks again!!


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## beenthere (Oct 11, 2008)

While #2 fuel oil does burn dirtier then #1 kerosene.
That will not in itself cause the cad cell to get sooted up.
There would have to be other troubles.

Delayed ignition. Is often a cause of of a dirty cad cell.


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