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Reducing nozzle size 30 yr old PB boiler

PerliePerlie Posts: 1Member
I have a 30 year old Peerless WB085-WPCT (WB3) with a DHW coil running a Beckett AFG burner using a 0.85 80A nozzle running at 0.89 gals/hr. A heat load calculation using an online calculator came up with 83,000 Btu s needed @ -10F for our 2100 sq. ft. house in this area of Vermont. I wired in a hour meter to the burner last fall and found that when the outside temperature was @ -2F and the boiler was bring the inside temperature from 65F to 70F the burner ran for 1.15 hrs during a 2 hr. period. From everything I have read the current set up for my boiler is more Btu s than is needed for my house. I want to downsizing the nozzle to 0.75. I called Peerless to find out their recommendation, but they don't have the specs for this boiler seeing that they bought the original company in the early 2000s. I was wondering if anyone has an idea whether I can have my tech put in a 0.75 80A nozzle or do I need a different one. I am asking for help here because most of the people I have talked to in my area seem to want more Btu s than less and change is hard. Thanks for any help.

Comments

  • Ron Jr._3Ron Jr._3 Posts: 562Member
    Not a problem downsizing the nozzle to that size. We set up new WBV3 boilers with the AFG and a .75 nozzle. Just have to make sure the end cone head is the right size , as well as the static plate of the nozzle assembly. And a burner baffle might be needed. And definitely an efficiency test . I have the same boiler and fire a .50 , which I believe is the lowest firing rate for that model.
  • STEVEusaPASTEVEusaPA Posts: 3,063Member
    Full combustion test required, draft, smoke, efficiency. If you have proper draft and true zero smoke you'll be ok. But more important is that your net stack temperature doesn't get too low.
    I never downfire, for reasons I've stated many times before.

    And never would I take a system spec'd for .85 and downfire to .50 (at the same pump pressure).
    steve
  • Ron Jr._3Ron Jr._3 Posts: 562Member
    > @STEVEusaPA said:
    > Full combustion test required, draft, smoke, efficiency. If you have proper draft and true zero smoke you'll be ok. But more important is that your net stack temperature doesn't get too low.
    > I never downfire, for reasons I've stated many times before.
    >
    > And never would I take a system spec'd for .85 and downfire to .50 (at the same pump pressure).

    This particular boiler can be downfired to a .50 nozzle. Had to be a Riello F3 , but the output is the same as any other burner would be at a given pump pressure.

    Never say never ! :)
  • STEVEusaPASTEVEusaPA Posts: 3,063Member
    edited August 21
    You are not saying the same thing I stated. You didn’t take a boiler spec'd by the manufacturer for an 85x.80B and downfire it to a .50 at the same pump pressure.
    A .50 @ 145psi is a .60 gph output.
    steve
  • HVACNUTHVACNUT Posts: 2,318Member
    edited August 21
    I dont know about 30 years ago but the current WBV manual shows the smallest nozzle for the AFG is .75 @ 140 psi with an F3 head and a 3-3/8" static plate. The Riello F3 can fire a .50 @ 145 psi.
    Not exactly apples to apples.
    There's only so much you can do with a fixed head.
  • Ron Jr._3Ron Jr._3 Posts: 562Member
    > @STEVEusaPA said:
    > You are not saying the same thing I stated. You didn’t take a boiler spec'd by the manufacturer for an 85x.80B and downfire it to a .50 at the same pump pressure.
    > A .50 @ 145psi is a .60 gph output.

    True. But only for the Riello F3

    Beckett AFG , NX and Carlin all keep a fixed pump pressure for each nozzle size in the WBV3.

    The Peerless WBV3 has a wide firing range. From .50 to .90.

    I thought you were talking more about downfiring a boiler . Not about pump pressure specifically.
  • Robert O'BrienRobert O'Brien Posts: 3,135Member
    The ability of the venting system to handle reduced flue gas temperatures is the limiting factor.
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