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AFUE must go?

Is that it [supposedly] provides comparison not only between boilers of wildly different classes (steam, conventional water, condensing, condensing/modulating), but between boilers and forced air furnaces!

Based on AFUE alone, a high-rated furnace [should] take significantly less fuel annually than a traditional boiler in a given structure. I realize this is mainly anecdotal, but it's rather well known that the hydronic system will be very comparable with the edge often going to the hydronic system. (This given reasonably typical systems installed typically and not hacked up with later modifications.)

Then try to compare a condensing/modulating boiler (AFUE similar to "advanced" forced air) installed in a suitable system and you're utterly faced with the idea of significantly higher than 100% AFUE!!!

How can this be?

While I respect Glenn Stanton's statement that, <I>"...All in all I feel it is a fair set of guidelines that tries to take into effect system efficiency issues along with boiler efficiencies..."</I>, I must take issue with how "system efficiency issues" are regarded.

I cannot help but think that those "system efficiency issues" effectively show forced air in the best possible light, conventional hydronics in the shadows and high-efficiency hydronics in the dark!
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Comments

  • John Ruhnke
    John Ruhnke Member Posts: 882
    AFUE must go!!!!!

    AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!! AFUE MUST GO!!!!!


    JR

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  • Brad White_64
    Brad White_64 Member Posts: 11
    How did I know...

    that you were the author, John, before I read the message...?

    It is not pronounced "ah-fooey" for nothing!

    Yours in agreement,

    Brad
  • Supply House Rick
    Supply House Rick Member Posts: 1,404
    Ditto

    AFUE actually sells boilers, incredible...

    Rick
  • heatboy
    heatboy Member Posts: 1,468
    It's just a number.

    Sort of like EMPG. Means nothing when purchasing a vehicle. In all of my years, I have never had a customer buy or not buy a boiler due to AFUE ratings.



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    heatboy



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    "The laws of physics will outweigh the laws of ecomomics every time."
  • It's a standard!

    We all adhere to standards that allow for fair comparisons of equipment. Regardless of the standard whether it be AFUE, Thermal Efficiency or Combustion Efficiency most equipment ratings will still compare similarly. I feel that AFUE does a good job of comparing how a "boiler" performs with the test criteria used in the ratings. This is more in line with real world scenarios in that it compares how the "boiler" works with the "system" and not just laboratory conditions with a heat distribution unit parked right next to a boiler. All in all I feel it is a fair set of guidelines that tries to take into effect system efficiency issues along with boiler efficiencies. Just my opinion!



    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • John Ruhnke
    John Ruhnke Member Posts: 882
    It doesn't do justice........

    Glenn,

    AFUE doesn't work well with hydronics. All of the boilers are tested at the same water temps. The water temps greatly effect the performance of the boiler. Condensing boilers often have a AFUE rating of about 5% to 10% higher then conventional boilers. Often though the savings are much higher like 50%. If a client thinks he will only gain 5% to 10% he is less likely to upgrade to a condensing boiler. This hurts our country greatly. It causes people to make the wrong choices and install equipment that costs them a lot in fuel bills. A more accurate comparison would reduce fuel consumption here in America and help manufacturers to make the right choices in boiler design, here in America. Please read ASHRAE Journal July 2006 page 51 to find out what I mean. You can download it for free from ASHRAE.org website if you are a member. Non members are $8.00. The article points out the huge savings with outdoor reset and condensing boilers.

    JR


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  • John

    I think you are misinterpreting what I am trying to convey. AFUE ratings take into effect how the boiler will perform with a system operating in a greater "system efficiency" mode such as 140°F supply water and 120°F return water. Consider for example a standard electronic ignition direct vent boiler with an AFUE of about 83-84% as compared to a Burnham Revolution direct vent boiler with variable speed injection built-in and an AFUE of 87-88%. The boilers are similar as far as construction and gas train but the big difference is the way the boiler handles the cold return water thus resulting in a much higher AFUE. The Revolution II takes this another step up the ladder by utilizing a secondary heat extractor to use flue gasses to warm up the return water before it enters the boiler and therefore gets a 90-91% AFUE rating. The AFUE ratings take into effect thermal efficiency, combustion efficiency and possible system efficiencies as well. The homeowner will appreciate fuel savings regardless of whether he is operating with cooler return water or not. As with condensing boilers it would always be more desirable to apply all of the test criteria such as the cool return water.


    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Ike Gatlin
    Ike Gatlin Member Posts: 65
    wrench

    If AFUE takes all those things into account.... how come low mass products can’t make the amazing AFUE numbers high mass products can? Mass stores energy right? If the energy isn’t applied to "work" then it is wasted right?

    Ike Gatlin
    Learning is fun.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    John, when you say

    "Often though the savings are much higher like 50%"

    What are you comparing the condenser to? A brand-new non-condensing boiler, installed properly? Or the old coal-converted one that was removed?

    You have to be more specific. These numbers you quote sound pretty wild if we don't know how you arrive at them. And they may actually turn people off- you know the saying "if it sounds too good to be true, it probably is".

    "Steamhead"

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  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80


    Technically they do take those things into account. They factored them into their "profile" for residential use. Interestingly enough they use the same "profile" for commercial applications.

    The "profile" they use is simply outdated and often mis-applied.

    All this being said I do believe there should be a AFUE rating; however, the test should be much more simplistic and it's terms posted on every sticker.
  • John Ruhnke
    John Ruhnke Member Posts: 882
    RE:

    > "Often though the savings are much higher like

    > 50%"

    >

    > What are you comparing the condenser to?

    > A brand-new non-condensing boiler, installed

    > properly? Or the old coal-converted one that was

    > removed?

    >

    > You have to be more specific. These

    > numbers you quote sound pretty wild if we don't

    > know how you arrive at them. And they may

    > actually turn people off- you know the saying "if

    > it sounds too good to be true, it probably is".

    > "Steamhead"

    >

    > _A

    > HREF="http://www.heatinghelp.com/getListed.cfm?id=

    > 367&Step=30"_To Learn More About This

    > Professional, Click Here to Visit Their Ad in

    > "Find A Professional"_/A_





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  • John Ruhnke
    John Ruhnke Member Posts: 882
    RE:

    Steamhead,

    1st off I want to say that these heating degree day analisys and hunches that I have done are on a Contractors level. When I do a research project, it will be much more accurate and detailed in info. Don't confuse what I have done in the past with my future Overall Efficiency Project. Are you refering to what I said? "Condensing boilers often have a AFUE rating of about 5% to 10% higher then conventional boilers. Often though the savings are much higher like 50%."

    What I am comparing to is a condensing boiler using outdoor reset to the old boiler coming out. The old boiler would be a hot water boiler about 30 or 40 years old piped and wired properly, maintained properly somewhat every year. Maybe it doesn't run 100% like new but not far off from it. I'll tell you this much. I have tuned a lot of old boilers and some of them run more efficient then some brand new boilers that I have tuned. Though on average I find the newer boilers of simular design more efficient by about 5% to 20%.

    This is not counting the old and way out of wack boilers, like coal conversions, or boilers with big fire boxes, boilers sooted up to the max. Efficiency Savings would be even higher for boilers like that.

    Also a lot of what I am talking about is hunches. I have done heating degree tests on a few projects. I also have reviewed heating degree day analisys done by others on other projects. I look for other projects a lot now. I find them in internet forums and trade journals. My hunches are well founded.

    I do agree that some of the savings is do to the old boiler's efficiency being off do to age.



    JR

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  • Tim_33
    Tim_33 Member Posts: 83
    I agree...

    with Glen on this one. No one can dispute that AFUE is a compromise and is not the absolute, in service fuel usage ultimate efficiency estimator. It is a relatively useful comparative number. Comparative, not absolute. Given two similar, competeing products, tested under identical conditions, AFUE is the best true comparison that you will ever have. OTH, try using AFUE to compare two vastly different pieces of equipment, even if they are both lumped in the "boiler" catagory, then the "user" is faulted, not the number.

    AFUE is certainly not perfect. I would advocate several classes of boilers be segregated for comparison, with separate criteria, based on a consensus of real world "typical" operating temperatures and delta T's.
  • Jim Davis_3
    Jim Davis_3 Member Posts: 578


    Because AFUE is based on a combustion efficiency calculation in the first place it is not a compromise but in fact bogus! There are an infinite set of O2 & Flue temperature readings that calculate into the same combustion efficiency when in fact actual performance could vary as much as 50%. I will admit that boilers are designed to a much closer set of standards than furnaces but the numbers used to rate them are still fictitious. When the flue temperature of an appliance is cooler than the water it is heating and it gets a higher AFUE someone is not paying attention. Having seen thousands of pieces of equpment in the field rated at 80 & 90% AFUES and only delivering 50-60% of their rating at factory specs it isn't hard to realize there is no consistency to AFUE rating and equipment performance.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    What I Believe to be the Major Problem with AFUE

    EQUIPMENT OVERSIZING! GROSS EQUIPMENT OVERSIZING!! RIDICULOUS EQUIPMENT OVERSIZING!!!

    Why do I say this?

    Because we have a problem with the term "heat loss" AND how such is calculated!!!!

    Face it. Structures in the real world are not well reflected by laboratory models that determine things like U-value, R-value, etc. Not only are the conditions infinitely changeable, but entire influencing factors are either ignored (the sun, occupancy gain) or assumed constant (wind from EVERY direction).

    I don't really have a problem with such assumptions and at least well-conducted calculations do seem to give quite accurate proportional compensation.

    The problem is that in each and every step of that "heat loss calculation" numbers are rounded up--this to include compensation to raise the heat level to design specifications. Combine that with what is either ignored or assumed impossibly constant and you what you wind up with is NOT a "heat loss calculation". What you get is a heat requirement calculation!

    EVERY SOURCE I FIND, be it "official" from ANY country or anectodal or from my own experiments shows that these "heat requirement" calculations overstate "heat loss" in a space where room temperature is maintained by AT LEAST 30% with 50% or more quite common!

    Again, I don't have a real problem YET...

    But what happens:

    As designers and installers we CONTINUE TO ADD MORE EQUIPMENT POWER!!!! We KEEP figuring up!!!!!!

    It begins at the beginning... Recommendations from the likes of HVAC-Calc (which I consider a great Manual-J program) REPEATEDLY stress that such calculations are the "bare minimum" and suggest that additional equipment power should be added! BUNK! FOOLISH!

    Then we often add some "extra" by reducing the design temperature. I'm guilty of this myself--I use the lowest authoratitive number (regardless of age) I can find.

    Then many will use a design indoor temperature significantly above an already generous 72F at design conditions.

    Then, we have this barrage of equipment output ratings. Not at all uncommon to use the lowest (I=B=R)--after all it "compensates" for the distribution system...

    Then when selecting the equipment we frequently size to the next size UP!!!

    By the time all of this is done, what we typically end up with is a heating plant nearly double the size of a heat requirement that is already doubled with regards to true heat loss to maintain your indoor design conditions!!!!!

    ---------------------------------------------------

    Back to the MAJOR problem with AFUE. It [seems] to assume that equipment is PROPERLY sized and completely ignores reality where it is grossly, horridly, ridiculously and insanely oversized.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    The Effect of Equipment Oversizing

  • John Ruhnke
    John Ruhnke Member Posts: 882
    AFUE is not remotely close............

    Tim,

    AFUE is not even remotely close. That is the big problem. The government dumps millions of dollars into this program. There is no correlation between AFUE and how efficient the boiler runs in your home. I have tuned up old boilers that have been in the field for many years, with an AFUE of 80 or less and got better combustion efficiency results then some new boilers with an AFUE of 85 to 88. Two indicators to look at are oxygen levels and stack temps. You want the lowest possible oxygen content and the lowest possible stack temps. The lower the stack temps the better the heat transfer was. The lower the oxygen content the more of the flue gas was used in the combustion proccess. The excess air pulls excess heat from the boiler and carries the heat up the chimney.

    Also water temps in the boiler have a huge effect on the efficiency of the boiler. An American conventional boiler found to have an AFUE of 88 when tested at 140 actually runs at 180 in the field. The boiler cannot be set to have lower then 140 return water temps. That relates running 12-20% less efficient in the field then lab tests. A condensing boiler is also tested at 140 degrees. At 140 the boiler won't even condense. If you take that condensing boiler and tie it into a low temperature radiant heating system running with outdoor reset and a design temperature of 120 degress it will run much more eficient. The boiler will gain efficiency from two different sources. Source one is the drop in temperature. The drop in average water temperature will cause a improvement of in 12- to 20%. Also there will be another improvement due to the recovery of heat from the condensate which will cause an addional 5 to 20% improvement in efficiency. The AFUE may state that the difference between a condensing boiler and a conventional boiler is around 5 to 10%. But after analysing many heating degree day analysis's done on a before and after cahange out from conventional boilers to condensing boilers we are seeing a increase in efficiency of 40 to 76%. Yes 40 to 76% that is a huge difference. AFUE does not show real world conditions in any way shape or form. It does not help the consumer to make the right choices when changing out a boiler and it causes American boiler manufacturers to produce a substandard product which greatly lessons the chance of them selling oversees. This weakens are economy badly. The average conventional American boiler is designed for a minimum return water temp of 140 degrees. Buderus can take 110 degree and Veissmann can take 90 degree return water temps.


    AFUE is very bad for this country.

    John Ruhnke

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  • John

    Your comments regarding the American manufacturers making equipment that is somewhat substandard in comparison to European manufacturers are totally unfounded. the Euro company "claims" of being able to operate with temperatures that low are just that...."claims". you can't take their standard equipment and install it without adding a very expensive control device.

    It doen't matter what testing standard is used to rate boilers because you will seldom find "laboratory conditions" on jobs in the field. You are seeing older equipment with higher combustion efficiencies than newer equipment because there is some sort of imbalance due to installation issues. In the overall long run combustion efficiencies are all related to the same three things...."Air. Fuel and Draft". If all three are in correct parameters, then the overall efficiencies will be as tested. Is that the fault of the equipment manufacturers.........NO!

    Field installation issues are the things that I always stress in my training seminars. I call them the "invisible problems" because you can't see them without proper instrumentation. Yes the AFUE ratings are based on low water temperatures. That is done because that is the dividing line of where things start to go wrong with boilers that were NOT meant to condense.

    It is a "standard" and as a comparison is a fair standard provided the jobsite conditions are such as those of the lab, which as you and I both know is seldom. Reset technology is a growing standard in the boiler business and operating with lower water temperatures is a growing trend. That, my friend, is "System Efficiency" and NOT boiler efficiency and is taken into effect with AFUE. If the American manufacturers simply took "Thermal Efficiencies" you would indeed see where the Euro companies really are in ratings.....low to mid eighties at best. If you could look at standby losses of those other boilers with some of the "thermographic imagry" equipment that we use for testing you would think twice about some of the comments you are making here. I'm not sure what this Anti-AFUE rage is all about John, but if you look back at your posts and the points I have been trying to make you will see that all in all it is a fair measure based on present and upcoming technology trends. Just my two cents.


    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Tim_33
    Tim_33 Member Posts: 83
    AFUE is...

    ??

    Can you answer that question John?

    Can you tell me in some understandable, concise way, how boilers are tested and rated for Annual Fuel Utilization Efficiency? What water supply temperature do they use? What return temperature do the use? What flow rate? What are the conditions of the room? What are the flue temperatures and the gas pressures, and the ratio of excess air, and the combustion air humidity level? If you know all of these things (and the many more that are involved) and can tell me why they are inappropriately chosen, then I and many others will listen to your criticisms. Otherwise, there is no credibility in your rantings.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928


    Sorry to interject Glenn, but something you said troubles me...

    "....'Air. Fuel and Draft'. If all three are in correct parameters, then the overall efficiencies will be as tested."

    Doesn't the neglect something very important, namely heat transfer efficiency? You can approach perfection of combustion, but if you can't transfer the energy produced effectively the true efficiency of the appliance (and this is not "system" efficiency) can be dismal. This does make me tend to think that a rather high degree of "designing for the test" may be occurring...

    I do respect AFUE as a reasonable comparison between appliances of a similar class, and they even seem to be reasonable when comparing forced air (of any sort) and traditional hydronics.

    What I do not respect about AFUE however is the actual number. After all, it's supposed to be at least somewhat reflective of annual fuel utilization efficiency in real-world systems. How can you explain condensing/modulating boilers which by ALL reports when applied to even reasonably suitable systems result in fuel reductions MANY times greater than implied by AFUE and WELL ABOVE 100%???




  • Tony_23
    Tony_23 Member Posts: 1,033
    Exactly

    I've taken CI boilers with a combustion efficiency of 85% (actual, not rated), replaced same with an Ultra, and cut usage 40%. Did NOT connect the reset feature at the time because of the 32F confusion and ran it for a year with those results. Yet the Ultra is AFUE'd at 92%. BS, plain and simple.

    Also, I'd like to know HOW a boiler with 3" of jacket insulation loses more in stdby than one with MAYBE an inch of insulation.

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  • Hi Mike

    I will agree that if the appliance to transfer the heat is hindered by a dirty or sooted up heat exchanger, then the AFUE will pay a pretty serious sacrifice. But that is a byfunction of proper Combustion Air, Fuel and Draft as well as the sizing of the system pump(s), system pipe sizing and just about everything else relating to that boiler.

    I'm not here to argue but until someone else comes up with a better standard (and that is exactly what AFUE is....a standard) to compare the various equipment by, then we will have to accept it. All be it that they are based on laboratory testing standards and criteria. Unfortunately I've yet to see a fuel savings of 100% with any equipment installed. As stated in an earlier post the testing is based on 140°F out and 120°F back to the boiler. If the equipment can operate with lower temperatures then lower system temperatures will improve the AFUE beyond the test conditions. I will also agree that possibly a different set of values may be in order for the Mod/Con boilers using for example 90°F-100°F water instead because by design they are not operating in the danger zone since they want to condense.

    But on the other hand, when a condensing boiler is misapplied in a system that can not operate with water temperatures conducive to condensing, then the perceived AFUE values will no longer be accurate either. Sure you will save something with the reduced firing rates but you won't have anywhere near the sytem efficiency as tested in the lab.

    All in all this is a very complicated matter. There will always be situations where you are not getting the claimed AFUE ratings and there will always be situations when you may exceed the laboratory testing values. But again, it is intended to be a standard for comparison purposes. These values are simply what the equipment is capable of achieving provided all of the described conditions are right. I'd still like to see that job with the 100% fuel savings though.

    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Tony

    You too are confusing Combustion Efficiency with AFUE Efficiency when they are two completely different things. I've seen 30-40 year old equipment with combustion efficiencies of 84% but that doesn't mean they have an AFUE rating of 84%. AFUE is a measure of Combustion Efficiency, System Efficiency and Thermal Efficiency and it also takes into effect numerous other things such as burner cycling flow rates and too numerous things to mention here. It is a standard that is used for equipment caomparison purposes primarily. It shows what the equipment is capable of when utilizing all of the criteria used in the testing procedure. Some eqipment simply does better and some does much worse.

    If you go out and install a boiler in a house that is properly sized using a reset control and then install the next larger size in an identical house next door without using the reset control then you will achieve two entirely different AFUE ratings for those installations. Can you measure that with instruments? Maybe.....but the homeowner will let you know all about it when he finds out what the guy next store spent for fuel. That is the gauge! Is this the testing Agency's fault? No! Is it the boiler manufacturer's fault? No! Will it ever be a true gauge of what you guys will see in the field? No! There are way too many variables in the field. Is it a true guideline for the homeowner to gauge his buying decision by? Yes. It is a fair guideline because all of the equipment manufacturers abide by the same guidelines or standards. Without these sets of standards it would be a "free for all" of of Marketing Claims such as we hear about on this sight and others every day.


    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Tony_23
    Tony_23 Member Posts: 1,033
    Sorry, I have to disagree

    A CI boiler with an AFUE rating of 83% is more than 9% less efficient than the Ultra rated at 92%. I'm not comparing 40 yr old equipment against the Ultra, I'm comparing a 16 yr old. I'm not comparing neighbors, I'm comparing the SAME HOUSE WITH THE SAME OCCUPANTS WHO KEPT GOOD RECORDS. Avg daily temps vs. the CCF used.

    With all due respect, you seem to be dancing around the subject by injecting hypotheticals into what we are saying we see and experience, while at the same time saying that AFUE encompasses more than we know w/o telling us what those "mystery" things are. Enlighten us. Don't bet the farm on me not understanding you.

    I look forward to the full explanation of what AFUE encompasses, as I am sure, do others :)

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  • Tony

    > A CI boiler with an AFUE rating of 83% is more

    > than 9% less efficient than the Ultra rated at

    > 92%. I'm not comparing 40 yr old equipment

    > against the Ultra, I'm comparing a 16 yr old. I'm

    > not comparing neighbors, I'm comparing the SAME

    > HOUSE WITH THE SAME OCCUPANTS WHO KEPT GOOD

    > RECORDS. Avg daily temps vs. the CCF

    > used.

    >

    > With all due respect, you seem to be

    > dancing around the subject by injecting

    > hypotheticals into what we are saying we see and

    > experience, while at the same time saying that

    > AFUE encompasses more than we know w/o telling us

    > what those "mystery" things are. Enlighten us.

    > Don't bet the farm on me not understanding

    > you.

    >

    > I look forward to the full explanation of

    > what AFUE encompasses, as I am sure, do others :)

    > _A

    > HREF="http://www.heatinghelp.com/getListed.cfm?id=

    > 384&Step=30"_To Learn More About This

    > Professional, Click Here to Visit Their Ad in

    > "Find A Professional"_/A_



    If you look at your own words you will see that you are trying to compare Combustion Efficieny to AFUE when they are different things in actuality.




    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Tony

    I'm not dancing around anything. Simply stating that a boiler sizied at 100,000 btu output installed in a home requiring a 60,000 btuh boiler is not going to achieve 83% AFUE Efficiency. You can't measure this in the field as you are not equipped to do so and neither am I. You would need to monitor combustion efficiency, thermal efficiency, burner run times, burner input and countless other variables for an extended period of time.

    If you and John know of a better method then take it up with the agencies that govern this. I'm just not sure what you are looking for with all of this discussion. If an equipment manufacturer told you that their boiler was 100% AFUE would you feel better or would you believe them? On the other hand, why would you want to install an Ultra without using the reset feature? Do you know now how much more fuel you could have saved your customer.

    Fuel usage comparisons in changeouts are not a fair comparison because you don't know how that old boiler was sized and about a dozen other things about it's performance because that was done by someone else. Now you go in and install an Ultra that you know is sized right, that is burning correctly, has adequate combustion air and had a much better flow rate because you probably installed it primary-secondary. Of course you are going to appreciate a 40% savings! But does that mean that that old boiler with a rating of 83% AFUE was achieving 83%? No! The only thing you know is that you sized the new one right, installed it right and it is achieving better combustion efficiency because it is a direct vent boiler correctly installed. But on the other hand you aren't getting anywhere close to the claimed 92% the Ultra should offer because you just operated it for a season with 180°F water. If you don't believe that then activate the reset and find out how much fuel they really can save because AFUE test criteria is based on those lower operating temperatures.

    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Tony_23
    Tony_23 Member Posts: 1,033
    Glenn

    I said I ran the Ultra for that season w/o reset because of a programming problem. Do you know what that was ? Full temp at 32F. Not much good here. Reset alone doesn't add as much as you're implying or we'd just put it on existing boilers. Also, that Ultra ran at 160,tops, just like the old boiler. However, on light days, it may not hit target temp before shutdown. You talk about boilers that run at 180 as if that's the only temp they see, not true. An oversized, cold start boiler with adequate circulation and high volume might not see 180 for days. Besides, AFUE isn't based on 180 is it ? It's based on an unrealistic 140 supply, right ? How come we don't test at 180 ? AFUE has been out a lot longer than mod/cons. Shouldn't testing be done as close to design parameters as possible for accuracy ? Test a CI non-condenser at 180 and an aluminum mod/con at 140 or less.

    BTW, my comparison home that you say isn't accurate because I don't know the past... I used the same heatloss from my files for the Ultra as I did for the Crown. The Crown was 112,500 input 81 IBR output. The Ultra is an 80. The heatloss is 68+ by the "book". After a carpenter bought the house from the original owner and butchered up the piping into yet smaller zones I was out for about 3-4 years. The current owner called me in right after buying the house and I was shocked at the mess. We found the old lady's records and started keeping new ones. We also started experimenting. Aquastat made it to 160 and was able to maintain on a design day. Records were kept. They are compared to the first Ultra season and after w/reset (minor difference).
    I'm betting if I merely repiped the Crown the same as I did the Ultra and supplied comb air, the usage wouldn't drop even 20%. Of course, that's my opinion.

    There are so many differences between the Crown and the Ultra, from combustion air to HX material to modulation. How can one have 83% and the other only 9% higher ?

    You're right about not being a lab, in the formal sense. But most people don't care what lab results are, they care about their results in their home. They call references, not labs.

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  • Ron Schroeder
    Ron Schroeder Member Posts: 998
    Glenn

    Thank you for your time in explaining AFUE as you did here, I kept puzzling over this 100% plus effency stuff for a while now. While reading your post it made me think of a contruction contractor I once worked for when computers where first becoming popular in the field, he said if you don't like the answer to a question you just change the input numbers until you get the answer you want. THis is what I see here, we have a standard however if you change the input peramiters ie supply/return temps then the output is going to change and that standard now gives a skewed number

    Bruce
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,240
    Completely avoiding...

    ... the main topic here. Glen, one way to see 100% fuel savings is to have an extended house-warming party. With each human "emitter" putting out roughly 350 btu's, simply crowd more in on cold days and party outside on not so cold days. Privacy might become an issue after a few years though ;~)

    Solar is good too, along with an efficient shell.

    Yours, Larry
  • Solarstar
    Solarstar Member Posts: 82


    After chaseing solar ideas and heat loss in my building envolope over the last 15 years. Ive also learned the true value of air sealing, use of ridgid insulation.and of course my handy spray foam gun ...these efforts always pay off starting the next heating season of course.I must say I have learned so much here .Thank you all. Now I,m pursueing condensing boiler and low temp radiant with the odd TrV'd panelrad.Also chaseing Killawatts to get my house to 10 Kw /day from my present 20 ..so I can generate this 10 with PV,s.This will be a major challenge Paul
  • John Ruhnke
    John Ruhnke Member Posts: 882
    A better way.......

    Glenn,

    Glad you asked. As a matter of fact I do know some better ways. With better testing methods we could save this country billions of dollars in fuel bills year after year and improve the quality of boiler manufacturering here in America.

    First off heating system efficiency is broken down into two parts. Boiler side efficiency and system side efficiency. The two added together produce Overall Efficiency.

    Overall Efficiency is the measurring stick used to judge the performance of the heating contractor to install the heating system with the best design. Also Overall efficiency will alow us to compare on an equal level heating systems of different types, hot air, steam, hot water, warm water and condensing. We can monitor the results of overall efficiency by comparing heating systems before and after installations. This is done by a heating degree day or bin analysis or another related method. As Steamhead pointed out though the old system comming out is mostly in bad shape so some of the improvement gains are due to a drop off in performance by the old equipment. This makes the efficiency gains to look stronger then they actually are.

    Overall efficiency is described as the amount of btu's leaving the conditioned space (heatloss)averaged out to btu's per hour over a set period in time devided by the amount of btu's in the fuel inputed into the boiler averaged out to btu's per hour over the exact same period of time. Overall effiency changes with the seasons and is higher at peak loads in the winter and lower in the spring and fall.

    We can measure this by installing a flow meter to a data logger. Then we need to analyse the fuel for btu content.Measuring the heatloss is a bit complicated. It would take a full page to explain the proceess and I won't go into detail here.

    To split up the measuring of boiler side and system side efficiencies is easy to do. We install a btu meter on the feed and returns as close to the boiler as possbible. On the boiler side of the btu meter we have boiler side efficiency and on the system side of the btu meter we have system side efficiency.

    Measuring boiler side efficiency in the field is real easy to do. You can also use the same measuring method in laboritory conditions. Two data loggers hooked up to the flow and btu meters will give you the boiler side efficiency. Just take the amount of btu's leaving the btu meter averaged out to btu's per hour over a set period in time devided by the amount of btu's in the fuel inputed into the boiler averaged out to btu's per hour over the exact same period of time.

    Measuring boiler side efficiency is real easy to do and a lot more accurate then AFUE. AFUE is a very long set of rules regulations and adjustments to the original efficiency calculation. It is very complex and because of its complexity becomes very unaccurate quickly.

    Measuring boiler side efficiency and making notes as to how the equipment was set up. such as what water temps are used is much more accurate. Boiler side efficiency should come with a rating for different average water temps to aid a home owner in choosing the best equipment for his home. Some systems such as hydroair can only run at higher water temperatures. The homeowner should be able to look at a chart and find the efficiency of the boiler based on the required system water temperatures.

    Measuring boiler side efficiency is real accurate and easy to do. I have applied for a Government grant with the DOE on testing heating system efficiencies but was turned down. I have a patent pending on a method of measuring overall efficiency with computerized monitoring equipment. I am currently working with a heating control company. We have discussed measuring boiler side efficiency when testing out his controls and might set up a few test houses this year depending on our budgit. I would love to do work with the DOE in future projects.

    I was a chairman for the energy efficiency action group for the RPA. They recently disbanned the whole group and shut down my project all based on one e-mail that I wrote. One e-mail and they killed th whole project. It is hard to deal with people sometimes, they are so unpredictable and unforgiving. They expect you to perform perfectly all the time and with one simple mistake they come down on you like a ton of bricks. I can't be expected to function like that. I made mistakes in the past and will make them in the future. Along the way to success lots of mistakes are made. it is part of the learning proccess.

    JR

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  • Christian Egli_2
    Christian Egli_2 Member Posts: 812
    73.8% no bull

    The big fault of AFUE is not that it should go, there are many other test standards out there all equally valid, I=B=R, DoE, EDR, ETC..., it's just that AFUE should not be oversimplified and overamplified the way it is with the giant yellow stickers that scream numbers at passing shoppers.

    It is clear many here are waiting to have the full knowledge behind AFUE. What do you think the common man in the street has? AFUE is just a number. Do our wives all think bigger is better? I won't admit knowing anything about AFUE... except that it is another government design just like the EPA numbers stuck on impossible to remove labels on the inside of our new cars that tell us what magic gas mileage we can dream about. It has zero credibility - re the bungle associated with hybrid vehicles estimated miles per gallon.

    AFUE numbers such as 83.3 vs. 83.4 leading you to bomb one boiler over another is very misguided. Labels and pamphlets should be there to educate the consumer about what simple energy principles lie behind home heating; this would help build more common sense reasoning, just like this wonderful website does single handedly.

    More numbered ratings will only add more confusion. There are already so many of them. There are, however some we should pay attention to and others not.

    Numbers presented in percentage forms can be readily discarded. Unless you have the full behind-the-scene computation, you can be deceived very easily. Think of how politicians package their tax rates, inclusive, exclusive, it changes everything. Chimerical investment broker talk should sound familiar too. 50 deg C to 100 deg C is either a (-) 50% or a (+) 100% difference, but 122 deg F to 212 deg F is respectively (-) 42.5% and (+) 73.8 %, yet there has been no change in real temperatures... see how confusing this all is, we never know what we're talking about. 100% pure sounds better than just 42.5%, which number would you buy.

    Also, some counter axiomatic mathematical operations should be anathematized. Percentage values cannot be carelessly added or subtracted from one another. You've got a 50% discount coupon and you purchase a new dress labeled as 70% off-at-the-register; what will the cashier do? Surely give you a store credit for 20% of the value of the dress (70% + 50% = 120%). Make a stink, call for the department store manager. Percentages work best as marketing tools, and shopping trips are dangerous expeditions to go on.

    Should efficiency percentages stop at 100%? Do they in AFUE? There are boiler numbers I prefer by far. Here they are. They also have withstood the test of time.

    I like to know the square footage of the fire side surface of the heat exchanger in contact with the water. This is the old square feet, it is readily transformed into boiler horse power (which is arguably antiquated) and it also readily matches the very modern kilowatt, kW units (something old, something new). The burner energy input rate should be kept apart.

    This square footage number is very good for side by side boiler comparison and relation to fire power. Plus, if you don't trust the numbers, you can pull out a tape meter right there in the display room, and proceed to a rough check. Not easy to be lied to with a straight face. That's why also, the similar EDR numbers are so incredibly useful.

    On my wish list of specification data.

    I would like the weight and metal composition of the nude boiler exposed on the label, along with the weight of the water content. Why the weight? because I can double check it for myself with a simple scale and because it will also tell me whether there is actually enough metal to develop all the surface claimed in the number above. Plus, weight, mass and metal type directly relate to heating speed performance. Add another entry on the label for the heat carrying performance of the heating fluid.

    Now we're on the way to making sound comparisons, all on our own.

    With cars, the most important fuel economy number to consider is the total weight of the vehicle, everything else is principally related to this value. Why do the hybrids have higher efficiency numbers? because they are so light in weight (and to compensate for mightily heavy batteries, they made the car real small). Still, low mass systems are smart.

    Doesn't all this make loads of sense or what?
  • John

    That is all well and good if you have the equipment, expertise and most of all time to do all of that. We can't even get installers to take 15 minutes to read through the installation manuals let alone take days to log data. Sorry but I just don't see that happening at all so for now AFUE will have to do.

    Glenn Stanton

    Manager of Training

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Glenn

    I know you're right about those oversized boilers. At the end of the coming season I should have some numbers coming from the boiler replacements we've done this summer- not lab-quality but the best I can get. So far the old ones were at least 100% oversized, and we just looked at one which was worse than that. All have/had been short-cycling badly. Stay tuned- and it's good to see you so active on the Wall again!

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  • John Ruhnke
    John Ruhnke Member Posts: 882
    Lab tests........

    Glenn,

    I think you miss understand me. It is not the contractors in the field that do the monitoring. It is done by research projects world wide. Overall efficiency would be Funded by the governments, maybe 20 houses or so a year.

    Measuring boiler side efficiency is much easier then measuring AFUE. They should set up tests in the lab and measure boiler side efficiency with the equipment running in actual job site conditions not 140 degree water lab conditions. That is step one.

    Field research is very important and it should be done right. It should be done based on a proper comparison. So improvements and proper choices can be made. The first step is to develop that proper comparison. Once the proper comparison is developed then it can be used by future generations and other countries for years to come.

    The stuff I talk about doing in the field is not difficult. I know of two companies that are funded by the DOE. They have about a dozen employees eaach and they monitor homes. They don't measure overall efficiency though. The DOE is spending between 1 and three million a year on each company. This program I am talking about is a research level program that could be done world wide. It needs to be done.

    The first step to improvement is proper comparison.

    It is to bad that no one is listening to me.

    I have the ability to save this world billions of dollars in fuel bills here. My testing methods are not that expensive. I think I came up with around $300,000 to test a block of ten different houses. That includes developing some software. I can do it for cheaper then existing methods. My information is more valuable because it gives you a proper comparison.

    For roughly $30,000, the price of a geothermal system upgrade, I could monitor one house. By setting up the heating equipment for low water temps and condensing boiler I could end up saving more then the geothermal would in my area if that system happened to be electric. From monitoring one house I could develop and improve my ideas for monitoring in future projects.

    JR



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  • Christian Egli_2
    Christian Egli_2 Member Posts: 812
    Trust but verify

    Why I seem to worry so much about how accurately I can check for myself the values given on the specification labels?

    I put my full trust in the companies I select to do business with - think about it, does it make sense to be worried stiff about numbers while glancing over all the other issues of safety, durability, reliability, compatibility... I am going to eat and breathe everything that comes out of that boiler, so, I'll concern myself with chocking on numbers last.

    Such is life gagged by data.

    Still, there is the engineer within all of us. Science and machines are most definitely a fascinating part of our lives. Researchers who write papers all day long have the most fun (we should wonder), and one way to measure how much fun one scientific presentation was is to see how many people actually read it, followed it, duplicated it at home, and then went on developing it further with more ideas and improvements. Thus, one component of good research is to leave cookbook style instructions for everyone to redo the same tests at home. Nothing here is top secret, the many more people replicate your work and validate it (ahem...) the more of a genius the original guy becomes.

    So there, that's why I like numbers and data for which there is some realistic possibility that I can validate them in a test of my own. Mumbo jumbo falls short of this goal.

    Let's say you're the greatest cook, and you write cook books to the world. Of course, your pictures will all look perfect, air brushed and all. Surely you'll put captions stating such things as 100% delicious, 50% delectable, and only 42.5% sickening to the stomach... In your cookbook, would you leave out the actual ingredient list and the actual quantities needed to derive the final efficiency rating?

    If no one at home can replicate your five star recipes, your book will have no value. This is the whole appeal of French cuisine, it stands for universal methods. You can make it all yourself, your sauce hollandaise need not be store bought... though it may taste like a bottled elixir and still make you gag.

    Let's see what's for dinner:

    Bottled efficiency % numbers you pop in the microwave while wondering what you're actually eating.

    Bon appetit
  • John Ruhnke
    John Ruhnke Member Posts: 882
    People do listen to me.........

    Glen,

    People do listen to me I have gotten a lot of support over the last three years. Alot of people in the RPA have supported me and still do. Here on the wall I have found a lot of support. I need to get involved with ASHRAE on a commitee level. I feel that will help. I am a member of ASHRAE. I talked about this a little with a committe chair and he gave me a list of a few commitees to join. I have been in contact with people from the DOE but have not talked to anyone high enough in the food chain. When I applied for the grant I was told that my project didn't fit any solicitations. I need to convince some higher ups about my project first and get them to write a solicitation. Changing things takes time. I also am under funded. I used to self fund my invention projects but can no longer do so. I have two kids and a third on the way. I added a big addition to handle the expanding family. I more then doubled our square footage. I now have two mortgages. I barely make enough to stay afloat. I need to expand my business. I am stalled until I can move into my new office. That should be soon.

    JR

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  • Tim_33
    Tim_33 Member Posts: 83
    No answer means..

    No, Tim, I can't answer a direct question on this issue with specific real data. I would prefer to rant and rave and leave those details to the engineers and people that are not being kept down by the man, like me. I can understand why few will take you seriously.
  • Tim_33
    Tim_33 Member Posts: 83
    You're a heating guy

    right? People at rest, when taken into account performing cooling calcuations, are good for 220 sensible and 220 latent.
  • John Ruhnke
    John Ruhnke Member Posts: 882
    ASHRAE wants $350 for article....

    Hi Everyone,

    Remember the article about boiler efficiency that started all of this? I asked ASHRAE if I could post it here on the wall. They said they want $350 to post on an internet site.

    You can get the article yourself. Go to www.ashraejournal.com. Under "search for articles" type "Durkin" which is the authors name. Click on the article "Boiler system Efficiency". They want $8.00 to download the pdf. If you are an ASHRAE member it is free.

    JR

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This discussion has been closed.