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Downfired boiler

ralman
ralman Member Posts: 231
in THE MAIN WALL
who used a combustion analyzer to set the burner. I used the program from this site to check my heat loss to see if the smaller nozzle would be able to heat my home. I expected a slightly longer burner run time during a call for heat. With the old nozzle I would get a 5 minute burner cycle about every 40 minutes. The smaller nozzle is giving me a 5 minute burner cycle every 10 to 12 minutes. The thermometer shows the home temp is the same with both nozzles. I am going to be using way more fuel with the smaller nozzle due to frequent burner cycles. Can anyone explain why this is happening? If I go to a nozzle size bigger than the .85 will the time between burner cycles increase?

Comments

  • Rodney Summers
    Rodney Summers Member Posts: 748
    Check the boiler temp

    Remember a .85 nozzle puts out about 1 GPH while .60 is 3/4 GPH. Are you sure the burn time is the same for both nozzles? Underfiring a boiler too much will waste oil also. If your boiler size is spec'd for a specific size, I'd only drop down one size to say a .75. The lack of BTU's can cause condensation in the boiler and flue.
  • [Deleted User]
    [Deleted User] Posts: 0
    The input was

    changed from approx 119,000 btus to 91,000 btus, assuming 100# pump pressure. That is a 24% reduction. Your description sounds like something else has changed, not just the input.
  • Big Ed
    Big Ed Member Posts: 1,117
    Call for Heat could be different..

    You don't want to drop too far as mentioned. What was the stack and CO2 reading before and after the nozzle change.....What type make, model boiler and burner...

    The running times could be different depending on time taking. Burner cycle depends on other factor ..... Temperature of rooms, start or end of heat cycle, call for hot water, tempature of boiler,a change of aquastat readings ,outdoor temperature.....

    Other factor you should take in when dropping nozzle size is the condition of fuel supply.... A larger nozzle is more forgiven then a smaller one... Proper fuel storage set up and filteredsupply is a must or service calls will eat away any savings.....

    What did you home come in at, Heat loss that is ?
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