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Is it possible to test a boiler efficiency?

245

Comments

  • captainco
    captainco Member Posts: 801
    Yes we do have a bunch of Better Statistics (BS) than most. I am sure that is what you meant!!
  • ChrisJ
    ChrisJ Member Posts: 16,394

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    HVACNUT
  • captainco
    captainco Member Posts: 801
    One of my favorite people. Always question but don't close your mind to the answer with an uneducated opinion.
    Proving or disproving requires intelligence. Just denying only requires ignorance.
  • Gordy
    Gordy Member Posts: 9,546
    It doesn't take much to figure out if I have a beverage in an insulated container it will stay hot, or cold longer........
    HVACNUT
  • ChrisJ
    ChrisJ Member Posts: 16,394
    Gordy said:

    It doesn't take much to figure out if I have a beverage in an insulated container it will stay hot, or cold longer........

    No,
    And energy doesn't just disappear.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    GordyHVACNUT
  • captainco
    captainco Member Posts: 801
    Coffee = btus - 180 degrees
    Cream = Air - 40 degrees
    Cup = Heat Exchanger

    Coffee with no cream = 180 degrees = cup 180 degrees
    Coffee 60% with 40% cream = 124 degrees = cup 124 degrees

    Same amount of energy in both cups however the cream(air) absorbed or diluted it before it could heat the cup.

    This kind of information was first printed in the Beckett Professional Serviceman's Guide from the 70's?

    What they didn't figure was that with every one Oxygen you get 4 Nitrogens. So when adding cream we are also adding water which still ends up with the same problem. The available btus are stolen before they are transferred to the cup.

    Yes, both cups will stay the same temperature longer if they are insulated.
  • ChrisJ
    ChrisJ Member Posts: 16,394
    captainco said:

    Coffee = btus - 180 degrees
    Cream = Air - 40 degrees
    Cup = Heat Exchanger

    Coffee with no cream = 180 degrees = cup 180 degrees
    Coffee 60% with 40% cream = 124 degrees = cup 124 degrees

    Same amount of energy in both cups however the cream(air) absorbed or diluted it before it could heat the cup.

    This kind of information was first printed in the Beckett Professional Serviceman's Guide from the 70's?

    What they didn't figure was that with every one Oxygen you get 4 Nitrogens. So when adding cream we are also adding water which still ends up with the same problem. The available btus are stolen before they are transferred to the cup.

    Yes, both cups will stay the same temperature longer if they are insulated.

    Yes,
    But you didn't add creamer to those homes that had their insulation, windows etc improved. Creamer would explain the energy loss.



    You're saying they improved their insulation, did nothing with the heating system and yet the bills went UP.

    So my question was, where did the energy go? Either the temperatures of the houses went up greatly, or something else changed.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    HVACNUT
  • HVACNUT
    HVACNUT Member Posts: 6,504
    And if the cup is the house, and the coffee is the available BTU'S, they didn't add cream, they insulated the cup. Where did it go?
  • Paul48
    Paul48 Member Posts: 4,469
    Hold on a second..........There was some major facts left out of that equation. Proper size....Proper installation.....Proper function. That's like twisting @HVACNUT's example...using 4 quarters, meaning 4 representative parts of a whole, and then speaking about cents.
    No arguments....just discussion. :smile:
  • Gordy
    Gordy Member Posts: 9,546
    What cap was "trying" to say is the btu delivery system went unchanged without any improvements to it. However envelope improvements would most certainly allow the envelope to use less btus over time while the btu delivery system would see no efficiency improvements.
  • JUGHNE
    JUGHNE Member Posts: 11,317
    Back to Larry the OP.
    I believe he has LP and no meter to clock.
    Seems difficult to measure gas consumption for a season as one does not usually start with an empty tank at the beginning of the heating season.....plus needs the LP for DHW.

    A 24 volt hour meter connected to the main gas valve would give you the time factor. Then if the gas orifices were the correct factory size and LP pressure set to nameplate ratings, a close approximation of the gas consummation for 30 days could be made.

    Best would be a LP gas meter for the boiler only. Gives you a meter to clock and monthly consummation for the HDD calculations.
    More money though.
  • larryjbjr
    larryjbjr Member Posts: 69
    edited July 2017
    Actually, I put a 24 V hour meter on the furnace back in January. I watched it and kept tabs on it for all of February March April and May.

    Judging best I can it seems like I was using about 1 gallon of propane for every hour the furnace was running.

    Can't remember exactly how I came up with that figure, but I took into account the DHW usage.
  • captainco
    captainco Member Posts: 801
    First of all the houses in question had new 95% furnaces installed along with the sealing but were not checked or set up properly. The coffee, cream and cup comparison is the furnace only not the house. If the new furnace is less efficient than the old one then the sealing of the house may not show any dividends. Not saying it doesn't need it.

    Simple answer to the original question - If you replace your current boiler with a Mod-Con, you will see a substantial savings in your fuel bill in the existing house as is.

  • Gordy
    Gordy Member Posts: 9,546
    edited July 2017
    I'll believe the "substantial" savings when a right size properly setup Ci boiler is replaced with a right sized properly setup mod/con.

    When I see 30% reduction in fuel. Usually that is from an oversized boiler being replaced.

    Technically in a low temp system that can get a mod/con to condense 15% should be the reduced fuel consumption.
  • captainco
    captainco Member Posts: 801
    Cast Iron Boilers O2 = 6% - 9%
    Mod-Con O2 = 3%-5% 3% to 5% difference
    Cast Iron Boiler Flue T = 430 degrees 160 degree outlet Temp
    Mod-Con Boiler Flue T = 160 degrees 160 degree outlet Temp
    Every 30 degrees equals 1% efficiency = 9%
    Mod-Con Latent Heat Recovery = Add'l 10%
    Mod-Con over 20% higher operating efficiency assuming both are operating the best they can, which is rare on the cast iron boilers.
    Newer non-condensing induced draft boilers do pick up and extra 3%.

    Assuming the same house and same exact set-up, a 200,000 btu boiler operating at 140 degrees outlet temperature is more efficient than a 100,000 btu boiler operating with a 200 degree outlet temperature.
    Hint: 200,000 btu boiler - O2 = 6% Flue T - 410 degrees
    100,000 btu boiler - O2 = 6% Flue T - 470 degrees
  • Gordy
    Gordy Member Posts: 9,546
    edited July 2017
    captainco said:


    Assuming the same house and same exact set-up, a 200,000 btu boiler operating at 140 degrees outlet temperature is more efficient than a 100,000 btu boiler operating with a 200 degree outlet temperature.
    Hint: 200,000 btu boiler - O2 = 6% Flue T - 410 degrees
    100,000 btu boiler - O2 = 6% Flue T - 470 degrees

    With that being said are you saying that if the 200k boiler, and 100k boiler both had the same 140 outlet temp they would both be the same efficiency? If so then oversizing has no relevance to efficiency other than the short cycle quandary.

  • captainco
    captainco Member Posts: 801
    If they are both running at 65% efficiency they use exactly the same amount of fuel. One just does it quicker. In 1987 ASHRAE did a study that showed there was no significant difference in fuel usage when equipment was as much as 200% oversized.

    Short cycling can be minimized by setting control differentials a little wider. Sizing can be addressed with indoor-outdoor controls. We never recommend oversizing but the majority of the heating equipment in the field is too big most of the year. Down South it is oversized all the time and up to 300%.

    Short cycling does not cause flue condensation or thermal shock. Condensation is cause by underfiring, poor venting or poor combustion air and nothing else.
  • Gordy
    Gordy Member Posts: 9,546
    Sooo if that's the case what relevance does modulation have?
  • HVACNUT
    HVACNUT Member Posts: 6,504
    1987. I'm glad I'm not near any sharp objects right now.
    Gordy
  • captainco
    captainco Member Posts: 801
    Modulation allows them to recover more latent heat because of lower flue temps. Plus, they are the first modulating piece of equipment I have encountered in 37 years that maintains a low O2 reading in all firing rates, somewhere around 3% to 5%. Furnaces on the other hand have O2 readings above 10% in lower firing rates, some as high as 15% O2.
  • captainco
    captainco Member Posts: 801
    You must be looking in a mirror NUT:)
  • ChrisJ
    ChrisJ Member Posts: 16,394

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    HVACNUTMilanD
  • HVACNUT
    HVACNUT Member Posts: 6,504
    captainco said:

    You must be looking in a mirror NUT:)

    Sorry, what? I was away taking a fistful of Xanax.

    ChrisJ
  • captainco
    captainco Member Posts: 801
    Chris thanks for keeping it light-hearted. NUT I hope you feel better.
  • HVACNUT
    HVACNUT Member Posts: 6,504
    >> Thanks, I think its kicking in. I love you bro.

  • Gordy
    Gordy Member Posts: 9,546
    If your analysis is accurate and a CI boiler delivers 64% efficiency we should have many three section oil fired boilers (65k net) unable to heat the buildings on the design day (65k x .64= 42 KBTU to the building). The boiler would run at a 100% duty cycle. But, no oil fired boiler EVER runs anywhere near 100%. 60% on the design day would be a miracle. So, obviously, the efficiency is greater than 64%, or we would have no such thing as three section oil fired boilers that can perform on anything larger than a cottage.
  • ChrisJ
    ChrisJ Member Posts: 16,394
    > @Gordy said:
    > If your analysis is accurate and a CI boiler delivers 64% efficiency we should have many three section oil fired boilers (65k net) unable to heat the buildings on the design day (65k x .64= 42 KBTU to the building). The boiler would run at a 100% duty cycle. But, no oil fired boiler EVER runs anywhere near 100%. 60% on the design day would be a miracle. So, obviously, the efficiency is greater than 64%, or we would have no such thing as three section oil fired boilers that can perform on anything larger than a cottage.
    >

    It also suggests my boiler can output only 83750 and yet it can fill 94000 worth of radiation with steam not counting piping losses. WM rated it 104000 out from 125000 in but apparently that's a huge lie

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • captainco
    captainco Member Posts: 801
    WM boiler rated at 83% AFUE has a maximum net IBR rating of 73%. At one time I thought that IBR actually check for input and output by using actual input and then, gpm X Delta X 8.33 X 60 for output. Then I found the test protocol and found that not to be true. It is all based on a combustion efficiency test and additional assumptions.

    In the 80's I was in a meeting with Bacharach and their design engineers discussing new products. They ask me if they should add more efficiency calculations to their analyzers for additional fuels. When I stated that they already have enough bad ones and more won't help I thought they were going to pick me up and throw me out the door. They said their's were the same as everyone elses. I agreed and said they are all wrong. After the meeting one engineer walked me down the hall and agreed with me and wanted to know what they could do to change that. I said if you change that, which would really be expensive, no one would buy their analyzers because they would show everything less efficient.

    I have done many heat loss and gain calculations over the years and helped customers design systems. I have found the heat loss and gain calculations to be based on loose assumptions and better safe than sorry.
    Somethings are just always accepted because that is the way its always been. As ChrisJ posted earlier, question everything? And when you find it is not correct you will be considered a radical, a loose cannon, troublemaker etc.
  • ChrisJ
    ChrisJ Member Posts: 16,394
    edited August 2017
    captainco said:

    WM boiler rated at 83% AFUE has a maximum net IBR rating of 73%. At one time I thought that IBR actually check for input and output by using actual input and then, gpm X Delta X 8.33 X 60 for output. Then I found the test protocol and found that not to be true. It is all based on a combustion efficiency test and additional assumptions.

    In the 80's I was in a meeting with Bacharach and their design engineers discussing new products. They ask me if they should add more efficiency calculations to their analyzers for additional fuels. When I stated that they already have enough bad ones and more won't help I thought they were going to pick me up and throw me out the door. They said their's were the same as everyone elses. I agreed and said they are all wrong. After the meeting one engineer walked me down the hall and agreed with me and wanted to know what they could do to change that. I said if you change that, which would really be expensive, no one would buy their analyzers because they would show everything less efficient.

    I have done many heat loss and gain calculations over the years and helped customers design systems. I have found the heat loss and gain calculations to be based on loose assumptions and better safe than sorry.
    Somethings are just always accepted because that is the way its always been. As ChrisJ posted earlier, question everything? And when you find it is not correct you will be considered a radical, a loose cannon, troublemaker etc.

    The IBR rating includes a pickup factor.
    The DOE output does not.

    You should always question things, just as we are right now.

    There's nothing wrong with that.
    What there is something wrong with, is assuming everything is true. For example, 6 Horsepower Shopvacs that only consume enough power to be 1, MAYBE 2 Horsepower. Home theater receivers that are rated 800 watts because they can do 100 watts, and have 8 of those 100 watt channels, but in reality can only deliver 100 total limited by both heat sinks, and the power supply.

    Companies are getting away with flat out lying. Is it possible boiler mfgers are as well? Absolutely. But, things need to add up.

    My boiler specifically, has a DOE output rating of 104,000 btu/h with an input of 125,000 btu/h. The IBR includes room for piping and pickup losses. 125K in, 104K out assumes 83% efficiency, no?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • ChrisJ
    ChrisJ Member Posts: 16,394

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • captainco
    captainco Member Posts: 801
    Although this is not exactly 100% scientifically correct it is something that I walk through in class.

    125,000 btu input. (sensible heat- non-condensing)
    125 cu.ft. of gas = 112,500 btu(LHV) sensible heat @ 3600 degree flame
    At 2800 degrees flame or 6% O2 112,500 = 101,250 btus input

    If you are only producing 101,250 sensible heat input, it might be difficult to get 104,000 output.

    What input would be necessary to produce a useable 125,000 btus kinetic energy? Approximately 154,000 btus or 154 cu.ft.

    154,000 input - 104,000 output = 67%

    It is harder to measure actual btu output of a boiler because you need a good gpm flow meter. But based on measuring thousands of furnaces in the field, the above works out fairly close. Also the btus in the gas can vary from 930 btus per cu.ft. to 1030 btus per cu.ft.
  • captainco
    captainco Member Posts: 801
    ChrisJ - As you see the Net AHRI rating is 73%. Still an assumed rating based on combustion efficiency calculations only.
    If the HVAC industry had been Spanish they would still be standing on the shores of Spain and saying the world is flat.
    If the HVAC industry was astronomers, they would still be saying the Sun orbits the earth.
    If the HVAC industry was in the space program, they would still be saying the moon was made of cheese.
    The U.S government would not give the Wright brothers a patent for their airplane because they were told it is impossible to fly.

    But I still have "High Hopes!"
  • ChrisJ
    ChrisJ Member Posts: 16,394
    edited August 2017
    captainco said:

    Although this is not exactly 100% scientifically correct it is something that I walk through in class.

    125,000 btu input. (sensible heat- non-condensing)
    125 cu.ft. of gas = 112,500 btu(LHV) sensible heat @ 3600 degree flame
    At 2800 degrees flame or 6% O2 112,500 = 101,250 btus input

    If you are only producing 101,250 sensible heat input, it might be difficult to get 104,000 output.

    What input would be necessary to produce a useable 125,000 btus kinetic energy? Approximately 154,000 btus or 154 cu.ft.

    154,000 input - 104,000 output = 67%

    It is harder to measure actual btu output of a boiler because you need a good gpm flow meter. But based on measuring thousands of furnaces in the field, the above works out fairly close. Also the btus in the gas can vary from 930 btus per cu.ft. to 1030 btus per cu.ft.

    Hmmm.

    So how is the DOE output rating calculated if it's so far off?

    And how doesn't it cause huge problems for guys sizing by heat loss, and even going on the small side. There's a few guys on here that actually have systems running 100% on design day and not losing temperature, or barely.

    For my specific system, there's too many variables.
    I have no clue how accurate my heatloss calculation was. I don't know how accurately steam radiators are sized etc. So I don't know that I couldn't be 20K short, and even notice.

    But all of the guys sizing both cast iron HW boilers and modcons using the same heatloss methods..........that one is a bit confusing.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • captainco
    captainco Member Posts: 801
    Heat Loss and Gain are still mathematical calculations based on many assumptions plus.
    DOE, (Disoriented-Obstinant-Engineers) which knows nothing about combustion, merely approves information that has been given to them based on a standardized test protocol. This test protocol uses the mis-calculated combustion efficiency as the major component of the rating.

    In the 80's and 90's when I knew and worked with engineers at AGA testing labs,(now CGA testing labs) they told me some interesting things like they don't really know if the efficiency they use is real or not. They said they were just comparing oranges to oranges. More like lemons to tomatoes but that another story.
  • captainco
    captainco Member Posts: 801
    ChrisJ - I posted an article I wrote for our students earlier, showing 5 different sets of combustion readings that all calculated into the same efficiency on an analyzer. Do you believe they are all 82% efficient, because that is how they get their DOE rating?
  • Gordy
    Gordy Member Posts: 9,546
    Soo what cap is saying is IBR is the real efficiency rating, or closer to it.
  • captainco
    captainco Member Posts: 801
    Assuming perfect conditions, it is closer to correct, but still slightly exaggerated because perfect doesn't exist.
  • Gordy
    Gordy Member Posts: 9,546
    edited August 2017
    If we apply this IBR logic to mod/cons they are only 80% efficient.

    The ones that put IBR input in their specs. Seems HTP avoids this DOE/IBR confusion.
  • captainco
    captainco Member Posts: 801
    That is the one product I have tested in 38 years that actually works near its rating.
  • ChrisJ
    ChrisJ Member Posts: 16,394
    captainco said:

    That is the one product I have tested in 38 years that actually works near its rating.

    What about when 5-10 years old?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.