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  1. #1
    Join Date
    Sep 2009
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    Wisconsin
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    13

    26 Year Old Duomatic-Olsen - 90% Efficient

    I have a 26 year old Duomatic-Olsen furnace. It's a condensing furnace and is about 90% efficient. Single stage burner and only one fan speed. I replaced the blower motor 2 years ago and the combustion blower last year.

    I am looking to have a new Bryant 355CAV with the Evolution control installed because of the age of my existing furnace. I am having difficulty justifying it though because of the high efficiency of my existing unit. The $1500 fed tax credit is what is really making me take the plunge. Thoughts about replacing? Yes or no?

    I have a similar aged A/C by Rheem, it's a high-efficient unit also, and I am currently planning on keeping the old A/C. I live in Wisconsin so if the A/C croaks one day it's not as desperate of a situation. However, the furnace going out when it's 0 degrees out is another matter. Thoughts?

  2. #2
    Join Date
    Sep 2002
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    Northeast Ohio
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    While the DMO was a reliable and reasonably trouble free unit, it's due. I have over 100 of that brand out and 0 failures as far as heat exchangers yet. Can't say that about some of the other premiere brands I have installed or worked on. As far as the AC, what was high efficiency 26 years ago won't even come close today.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  3. #3
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    Sep 2009
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    Wisconsin
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    You have 100 of which brand out and 0 failures? The DMO or Bryant?

  4. #4
    Join Date
    Sep 2002
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    Northeast Ohio
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    Quote Originally Posted by Tony49837 View Post
    You have 100 of which brand out and 0 failures? The DMO or Bryant?
    DMOs. Can't speak for the newer Bryants but I have changed out some of the older high efficiency Bryants 12-15 years, because of HE problems
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  5. #5
    Join Date
    Nov 2008
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    1,673
    From my ~40 samples of HVAC lifetimes mostly taken from this forum, at 26 yrs you have a 50% chance of making it to 40 years at some level of reduced performance and safety.

  6. #6
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    Sep 2002
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    Quote Originally Posted by WhoIsThat? View Post
    From my ~40 samples of HVAC lifetimes mostly taken from this forum, at 26 yrs you have a 50% chance of making it to 40 years at some level of reduced performance and safety.
    You need to grade on a curve here. 90% condensing furnaces by their very nature invite corrosion. Couple that with the fact that the earlier ones were deficient in several different areas that anyone who has done this for 30 or 40 years is already aware and you don't have to be a rocket scientist (or metallurgist) to figure out that the odds of ANY 90% condensing furnace heat exchanger making it to the 40 year mark are practically non-existent. For example, the first DMO Ultra Maxs required you to physically rinse down the secondary heat exchanger annually. How many of those do you think will make it 40 years? I would venture a guess that are fewer than 5% of the Heat Controller Reclaimer series are still out there and who could forget the ever-popular Luxaire Heat pipe. If you want to take ALL furnaces as a group from the drum style single burner dinosaurs, to the ribbon burnered clam shells, to the power vented 80% and on to the 90%+ units and take your average from there, you still won't average out to 50% of the whole group making it to 40 years.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  7. #7
    Join Date
    Nov 2008
    Posts
    1,673
    Here's my distribution for resi. HVAC in the US.

    If you can supply several datapoints for subcategories [oil furnace, heat pump, gas furnace, other] I'll be glad to split these out into a separate distributions. This will make for more accuracy for poster's repair/replace decisions.
    10 datapoints is reasonable and 30 is considered a "statistically large" sample.

    HVAC replacement age in years

    how many have reached this age|age reached in years
    1|1
    1|6
    2|7
    3|10
    3|12
    1|13
    3|15
    2|16
    1|17
    3|18
    7|20
    1|22
    1|25
    1|26
    2|30
    2|35
    1|40
    1|46
    1|50
    1|56
    1|58
    1|80

    Mean = 17.0 yrs
    Median = 19 yrs

    ..0 to <10|xxxx
    10 to <20|xxxxxxxxxxxxxxx
    20 to <30|xxxxxxxxx
    30 to <40|xxx

    http://en.wikipedia.org/wiki/Skewness

    In my distribution only 5 out of 41 make to 40 yrs or older and 4 out of 41 don't make it past 7 yrs.

    I come to find out that people have many reasons to replace HVAC equip besides equipment failure.

    Been There will be along any minute now. . .

  8. #8
    Join Date
    Apr 2002
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    11,808
    Quote Originally Posted by heaterman View Post
    While the DMO was a reliable and reasonably trouble free unit, it's due. I have over 100 of that brand out and 0 failures as far as heat exchangers yet. Can't say that about some of the other premiere brands I have installed or worked on. As far as the AC, what was high efficiency 26 years ago won't even come close today.
    I bet that olson must have been through a few inducer fans, probably a couple in the first 5 years
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  9. #9
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    Sep 2002
    Location
    Northeast Ohio
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    Quote Originally Posted by Carnak View Post
    I bet that olson must have been through a few inducer fans, probably a couple in the first 5 years

    The early steel housed ones didn't last long but they changed to thermal plastics and made them retrofitable. I think the OP indicated that he had changed one recently, that would be unusual if that was the first one.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  10. #10
    Join Date
    Nov 2008
    Posts
    1,673
    "Fans" in general are supposed to last 40,000 hrs, some maybe going to 10 yrs. This info is hard to pull off the Internet.

  11. #11
    Join Date
    Apr 2002
    Posts
    11,808
    well when a metal fan becomes a paddle wheel slinging around acid, they tend to not last that long. Took them a while to go with `windjammers``as a replacement
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  12. #12
    Join Date
    Feb 2004
    Location
    Pacific NW
    Posts
    566
    If you can supply several datapoints for subcategories

    here is a single data point for you, will check out the HE again next month, last time checked was 2 years ago.

    Mom's Homart/Dornback NG furnace was installed in 1952. Still in use in boyhood home in Central IL. Remember watching it get installed. From inspecting the HE, it looks like it is stainless, but something less of an alloy than 303.


    Replaced the rubber bushings on the fan motor last time I checked the HE, motor still good. Pop oiled twice a year and replaced filter bi-monthly. Pop probably had replaced the fan belt sometime(s), all else original as far as I know. Since Pop died in 2001, probably has only gotten filter changed and oiled once a year. The motor rubber bushing may have failed from too much oil spilled on them for 55 years <G>

    So, that is a 57 YO statistic, still going strong.

  13. #13
    Join Date
    Nov 2008
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    Quote Originally Posted by junkhound View Post
    If you can supply several datapoints for subcategories

    here is a single data point for you, will check out the HE again next month, last time checked was 2 years ago.

    Mom's Homart/Dornback NG furnace was installed in 1952. Still in use in boyhood home in Central IL. Remember watching it get installed. From inspecting the HE, it looks like it is stainless, but something less of an alloy than 303.


    Replaced the rubber bushings on the fan motor last time I checked the HE, motor still good. Pop oiled twice a year and replaced filter bi-monthly. Pop probably had replaced the fan belt sometime(s), all else original as far as I know. Since Pop died in 2001, probably has only gotten filter changed and oiled once a year. The motor rubber bushing may have failed from too much oil spilled on them for 55 years <G>

    So, that is a 57 YO statistic, still going strong.
    You've just raised the average from 17 years to 18 years.

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