Afue?


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Old 02-02-03, 05:37 AM
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Question Old oil furnace efficiency?

I am replacing my old oil furnace. Its a 1970s model Armstrong L61-112 (112K BTU/hr) unit. Anyone have an idea of how efficient that was rated at? I am just wondering what the efficiencies were back in the ole' days. Peace: e3 - spamman

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I changed the title of the thread to more accurately describe your question.
 

Last edited by GregH; 02-02-03 at 09:36 AM.
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Old 02-02-03, 12:39 PM
fjrachel
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You can figure that yourself and get somewhat close by taking a stack temp. reading
1000d=65 to 69%
800d=70 to73%
600d=76 to79%
400d=82 to84%
 
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Old 02-02-03, 12:53 PM
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excellent info

not being an oil man i had no idea. thanks fjrachel.
 
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Old 02-02-03, 01:06 PM
fjrachel
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hvac4u,
Those numbers are really only good after the unit is set up correctly. Which would be 10 to 12% CO2 and no visable smoke from the stack. FYI
 
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Old 02-02-03, 02:01 PM
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I am assuming the 400d (example) is 400 degrees faranheit? I would need a thermocouple huh? I am not sure what the CO2 level is, but it should be logged on the furnace from his visit last week. I am getting really annoyed with this oily smell. But get this.... NO visible smoke on anything on any level of the house. They said there is a crack in the heat exchanger but I would assum to see some smoke on the white wall registers or on the light colored walls. nothing. e3
 
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Old 02-02-03, 02:17 PM
fjrachel
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CO2=carbon dioxide and you'll need a thermometer to measure stack(flue) exhaust temperature and check for smoke where flue exits house, not registers in the house. Yes, fahrenheit.
I doubt a CO2 test was done on your unit. Most techs who do that type of test would not have left you with the smell problem.
 
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Old 02-02-03, 04:18 PM
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oil burner

MY 2 cents.Old oil furnaces , if you set them right with a combustion testing kit we could set them at about 70% to 80% most of the time.You need the kit so you can set the draft , take the co2and then the temp.Do you still have that crack in the heat exchanger?????You can run the furnace some to warm it up then put in a small smoke pill and see if you get and smoke up in the home. Id do this to make sure there is no leaks in the furnce ED
 
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Old 02-02-03, 04:20 PM
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Unfortunately, the mid 70s wasn't the old days. Unless your burner has a 1725 rpm burner motor on it, it isn't much different that the new one you will get. If you have a flame retention burner, preferably a Beckett, you have the same unit you will be getting. No changes in burner technology have happened since the mid-late 70s. Sorry. The same holds true for heat exchangers. No different now than then. I hope you are not buying a new furnace to save money on fuel because it won't happen. Many advertisements say "call now to get a new furnace and save up to 15% on your fuel bill". What that really means is if you have a real dinosaur piece of crap, we can save you 5%. If the promise came with a guarantee, you would see a very different advertisement.
 
 

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