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downfiring

ChrisJ
ChrisJ Member Posts: 11,978
I'm curious if there is any benefit to downfiring an atmospheric gas boiler to fine tune a system.



For example when I install my new boiler if I find I could get by better with just a little less output (5-15%) would it benefit me at all, or would I simply burn the gas anyway due to the longer run times? 

The boiler I'm installing is an EG-45 which appears to be completely identical to an EG-40 other than having one extra burner.  I have to assume this suggests it could be downfired to match an EG-40 if the situation ever came around (radiators removed in future and so on).

I would of course have a professional do this for me if it is at all beneficial.
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

Comments

  • Tim McElwain
    Tim McElwain Member Posts: 4,481
    Size the boiler

    to match the heat loss and lineal feet of radiation. Down-firing is not a good idea as you have a boiler designed to fire at a certain BTU and then you lower the input and the efficiency goes down. Plan well ahead, hire a pro, have a heat loss done, match up your radiation, get it installed and leave it as it came.
  • ChrisJ
    ChrisJ Member Posts: 11,978
    steam

    Tim,

    I probably should have mentioned this is a steam system, however your point is well taken.  Downfiring reduces efficiency.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Steamhead
    Steamhead Member Posts: 14,850
    Well, it all depends

    on how aggressive the normal firing rate is.



    There are some boilers that are offered with several firing rates- the Smith 8 series and some Peerless models are two brands that come to mind. Typically, the efficiencies on these are higher at the lower rates. But I would assume if you went down too far, efficiency would drop.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • ChrisJ
    ChrisJ Member Posts: 11,978
    edited August 2011
    EG40 vs EG45

    steamhead, this is sort of why I wondered if it mattered that the EG40 and EG45 appear to use the same block part number. The only difference I can find is the 40 has a 5 tube burner while the 45 comes with a 6 tube burner assembly. Of course this doesn't mean that there are not other differences I don't know about.



    I do see what you are talking about in the manual to my Burnham KV83. It lists two nozzle sizes for a water system and the higher flow nozzle has a substantially lower AFUE rating.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • SusanC
    SusanC Member Posts: 106
    EG40 & EG45

    I once asked Weil McLain about this.  They said that the EG45 can be changed to an EG40 (or vice versa) if you change the manifold, back burner support, draft hood and of course the number of burner tubes, and readjust the gas.  Apparently otherwise the boilers are the same.  Is this correct?
  • ChrisJ
    ChrisJ Member Posts: 11,978
    Old

    Wow is this an old thread.  Turned out my EG45 is just big enough for my system so its a good thing I didn't go with an EG40.



    Susan as far as I am aware your statement is accurate.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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