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Mod Con question

Wayco Wayne_2
Wayco Wayne_2 Member Posts: 2,479
in THE MAIN WALL
a Mod Con Boiler more efficient. When it is at high fire, or low fire or somewhere in between?? WW

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Comments

  • Guy Woollard
    Guy Woollard Member Posts: 82
    When

    In theory, I would say that the beauty of the Mod/Con is that it "Should" be equally efficient throughout the modulation curve. I think in reality ,the efficiency is slightly higher at low fire, due to the potential for the return water to further cool the HX before the control ramps things up and the fact that at that point you have a large HX and a small BTU input- the recipe for more condensation.


    Guy Woollard
    N.E. Regional Sales Mgr
    Triangle Tube Corp.
  • Perry_3
    Perry_3 Member Posts: 498
    The Vitodens Efficiency chart...

    Indicates that it is most efficient at low fire.

  • [Deleted User]
    [Deleted User] Posts: 503
    Absolutely...

    LOW fire, as tested and confirmed on my in home laboratory situation. In fact, on low fire, working uphill against a head wind :-)

    ME
  • Mike E_2
    Mike E_2 Member Posts: 81


    Here is the chart Perry was referencing.
  • J.C.A._3
    J.C.A._3 Member Posts: 2,980
    Now, For the wrench in the spokes......

    I'm going to humbly DISAGREE with you ALL!!

    In my years of training and all the testing results I've EVER poured over....A boiler is MOST effecient....WHEN OFF !!!

    100%, no questions. Sorry Wayne. I just HAD to throw that in there. Chris
  • [Deleted User]
    [Deleted User] Posts: 503
    That's outside the parameters of the question.....

    :-)

    ME
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Chris

    What a great concept. I just walked into the boiler room and hit the switch to off. Got a warm fuzzy doing it too. It's warming up here in MD up to 60 today so they say. WW

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • [Deleted User]
    [Deleted User] Posts: 16
    Not quite 100%

    Since efficiency is defined as (output divided by input) x 100%, at best in the "off" case you're describing 0/0 which is "indeterminate." At worst, if there is standby electrical consumption to power a microcontroller while no firing is occurring, efficiency when "off" is 0/(a very small number) x 100% = 0%! This even ignores input to any external pumps used for constant circulation; it addresses the mod/con boiler only.
  • J.C.A._3
    J.C.A._3 Member Posts: 2,980
    Now Wayne....

    Take a jaunt outside...and watch the meter NOT SPIN !

    I rest my case...100% effeciency! How can you beat that?

    All kidding aside, Low fire, condensing like crazy and comfortable house...is the BEST possible effeciency for any mod/con. The lower bills just show who's smart!(and had the smarts to do it!) Chris
  • Brad White
    Brad White Member Posts: 2,399
    So, Chris...

    Say you spent a premium of $2,500 for a super-duper high efficiency boiler over a garden variety boiler type critter.

    Your savings are based on hours of operation.

    The boiler is off. The payback clock stops. The bank still gets their interest.

    :)
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • J.C.A._3
    J.C.A._3 Member Posts: 2,980
    In it's simplest form....

    Off IS the most effecient. If I even tought I could argue with Brad....I'm mistaken. But that's my story....and I'm stickin' to it !

    Sam, if the temp. is high enough...the pumps ain't running, and as to the "power module" using some juice...you're right. Lets just say 98 and 1/2% while off.

    Banks be damned! Chris
  • Patrick Linhardt, \"Linhardt's Field Guide to Ste
    Patrick Linhardt, \"Linhardt's Field Guide to Ste Member Posts: 152
    little help

    Hi Guy,

    I have a post going about twin mod/cons and an indirect in a 24 unit apartment building. The question is how to maximize the efficiency of the system, which is two PS250's and a TL-100. Each of the boilers has a DHW pump. The space heating is handled by a tekmar #261. This set-up is in two buildings.

    Do you have any suggestions or experiences?

    Best regards, Pat
  • Guy Woollard
    Guy Woollard Member Posts: 82
    Response

    I will reply privately,as the response may get lengthy, or may require more of a dialog. I will respond via the e-mail address supplied here.

    Guy

    Guy Woollard
    N.E. Regional Sales Mgr
    Triangle Tube Corp.
  • Doug_39
    Doug_39 Member Posts: 12
    Sometimes no premium

    Can't say for sure what the situation is now, but this is our 5th winter with NTI's Trinity which was installed at no premium to a conventional boiler. More h/o's would make the choice we did if they were aware of the offering. When you think of all the folks running out to install compact fluorescent lights these days, imagine how many more people would have ModCons if only they were marketed to consumers as well as to the trade. The Trinity's affordable upfront cost combined with its ModCon efficiency savings is what has kept natural gas a competitive alternative to home heating oil for us.
  • bob_50
    bob_50 Member Posts: 306
    It seems to

    me that a boiler that is off is a RADIATOR and is exchanging heat from the water in the boiler to air in the vent system. When it's off it's a net loss sooo not 100% efficient.
  • [Deleted User]
    [Deleted User] Posts: 503
    Good point bob...

    and it reminded me of a condition I wanted to share with my fellow Wallies. You all remember the frozen broken CFT heat exchangerf debacle (Aerial heat exchanger replacement), well we were called back to the job due to dead pump motors. That is for a whole nuther thread, but what I found that was VERY interesting, is that of the three dead boilers on this TRUELY primary/secondary system, all three had the same water temperatures in them as the mains, with their secondary circulators DEAD OFF.


    And by ideal installation of P/S, I DO mean "IDEAL". This system is piped per the book. 5" S&R copper main piping with perfectly close stacked horizontal 4" branch tees serving the boilers with thier own individual (undersized) circulators, probably 10 X straight pipe before and after ins and outs. I can't get to the heart of the stacked tees to verify that they were properly reamed, but I can't believe that not reaming a pipe would cause that much PD across the tees. Also, the boilers are 3 to 4 foot below the mains.

    Thinking back, I suspect that the inhouse maintenance guys had valves closed to the boilers, thereby defeating mother natures freeze protection program, but still, according to all the information we have available to us, THIS SHOULD NOT BE HAPPENING!!!

    One of them thangs that'll make you scratch your head and go "Huh..."

    I'm thinking of doing a de-bunking myths article to show what your appliances do in their supposed "OFF" position.

    Reverse radiator fir sure...

    Just when you think you know what you're doing, Mother Nature jumps up and shows you WRONG...

    ME
  • Tim Doran_4
    Tim Doran_4 Member Posts: 138
    Lineal performance?

    I am not sure that the performance should be lineal. The heat exchanger surface area and fluid flow are constant and the variation is in the quantity of energy being introduced therefore the ratio of input to surface is on a curve and the performance should be inverse. I think!

    Tim D.
  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291
    Which brings up a question

    On the smaller version of the Vitodens, the boiler pump is variable speed. How does this effect overall efficiency because as you said Tim, in any other boiler, the flow and HX area are constant. It would seem to me that the variable speed feature, which is weather responsive and therefore water temp responsive, seeks to maintain the highest possible Delta T that it can. Would this not produce a greater condensing effect than a narrow Delta T? More condensation = greater efficiency?
  • Tim Doran_4
    Tim Doran_4 Member Posts: 138
    Seems Logical

    The Vitodens has two variables which should increase the arch of the curves. As flow and flame decrease and the HX surface remains constant the performance should improve significantly.

    Tim D.
  • Uni R_3
    Uni R_3 Member Posts: 299
    Dough Exchanger

    Let's say that there is about 5% waste. What % of that 5% are you going to save, and how much extra cost and risk are you willing to pay in return? It gets much tougher to make significant gains when the efficiency is already high. I'd be curious to know each side of the equation.
  • Cosmo_3
    Cosmo_3 Member Posts: 845
    Hmmm

    That was highly illogical

    Cosmo (wearing Mr.Spock ears)
This discussion has been closed.

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