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Is there a 3 pass oil boiler with a small rear clearance?

Are there any 3 pass boilers with a different design or at least with the rear manifold casting exiting somewhere other below the return pipe so that it can be inches from a foundation wall instead of feet?

I need to replace a 1992 Burnham V76 fired at 1.4 gph and the location doesn't have an extra 2 feet to accommodate a Buderus G115/215 style 3 pass with the rear exit flue trapped under the return and the relief valve. Someone must have figured out that the two side passages can be a Y shape and collect to a flue collar exiting upward.

The pin boiler was a pain in the neck to clean. I'd rather not do that again.

I get it that the 3 pass rear flue is a concept for direct venting through a side wall. I understand that slab houses don't have a basement.

in re: the boiler requirements: No DHW coil, load is 2x SSPH20 indirect pool heaters, plus 2 stage room heat. Stage 1 radiant pool deck. Stage 2 hot water coil in the air handler of a 3 ton dehumidifier. The boiler's firing rate is set by the time to raise the water temperature. Swim water bypass limits the heat load to return boiler water at 135 when both call for heat, but either SS20PH can transfer the entire boiler output by itself. Call for heat cycle is 30 minutes minimum, 1 hour typical. Space heat alone is a fractional duty cycle. The water heating load isn't a good fit with outdoor reset so intelligent controls are not a plus.


  • Robert O'BrienRobert O'Brien Posts: 3,163Member
    Nature of the beast with triple pass boilers as far as rear flue connector. How about an EK2?
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  • HVACNUTHVACNUT Posts: 2,838Member
    edited August 2019
    You clean the Burnham? Who services the burner and controls?
    The 3 pass boiler wasn't a concept for direct venting, it's a design for increased efficiency.
    The Buderus G215 specs 27.5" or a minimum of 16" between the rear of the boiler and the back wall. Biasi, 9", Trio, 17". Is this in an enclosed room? If a 3 pass was installed within the the allowable rear wall spacing, where is the space issue? Accessible burner service and swing out door? Will bifold or double doors help?
    Intelligent controls are only as smart as the people who install and program them. Most have options to override ODR, WWSD, to allow full input.
    And like @Robert O'Brien wrote, the EK-2 Frontier would be an excellent option.
  • PolychromeUgandaPolychromeUganda Posts: 5Member
    I was hopeful about 9" for a Biasi for a few minutes until i read 18" from the flue to any construction. After an elbow in the smoke pipe to clear the tappings above it ends up close to 30" from the back of the boiler shell to a concrete wall., I doubt unfinished poured concrete really needs an 18" spacing but there's no way around the way they write that one.

    The constraint is the space from poured concrete wall at front to poured concrete wall at back.
  • Jamie HallJamie Hall Posts: 12,124Member
    I'm sort of vaguely sitting here, trying to picture your space... and find myself wondering if you actually have space in there to install anything and adequately service it... just sayin'
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • STEVEusaPASTEVEusaPA Posts: 3,819Member
    Can you take a pic of the space or draw a picture with dimensions?
    Either way, the EK sounds like a winner. Top flue exit, all front access for service
  • PolychromeUgandaPolychromeUganda Posts: 5Member
    re: space there's roughly 3-1/2' in front 2-1/2' in front of burner , 2-1/2 feet to the right to movable barrier, 6" rear, 10" to left. At the left is another physically much larger boiler, 47w x 30d x 50h 1444lbs not including burner, jacket, or flues. The V7-6 was installed in the access passage to the space occupied by the other boiler. If the other boiler had had to come out, the V7-6 would have had to be temporarily de-installed to make that happen. The V7-6 was piped, fueled and powered with unions and disconnects to make that happen without a fuss. "The best laid plans of mice and men aft gang a glee". The other boiler is 12 years older than the V7-6. Re-orienting the replaement for the V7-6 boiler and moving the barrier would more than double the cost of replacing boiler. If it can't fit in the available space a biased estimate of 3 pass boiler vs pin boiler efficiency has a payback period over 15 years, and is a losing proposition using any available efficiency data.

    ... therefore the question -

    Has any boiler maker had the wit to cast a rear flue collector for their 3 pass boiler that exits at the top instead of the rear, or are they all just like so many sheep and slavishly copying the one design without making any effort to compete on anything other than the color of theio paint and their salesman's talent for slinging the manure of male breeding cattle ?

    in a time when one political party's candidates have been promising to put every last boiler maker out of business before 2030 you'd think one of them would decide to make hay while the sun shines and push some of the others out first...

    ..and if not, is there a brand that's either a cheery butter yellow or vivid turquoise blue?
  • STEVEusaPASTEVEusaPA Posts: 3,819Member
    You got some choices. Why are you banging away with nonsense? We don’t make the boilers nor do we have any influence on getting them to build a boiler just for your specific installation requirements.
  • HVACNUTHVACNUT Posts: 2,838Member
    That's more anecdotes than Carter's got liver pills.
  • Jamie HallJamie Hall Posts: 12,124Member
    Frankly, it sounds to me as though you are attacking the boiler manufacturers for not making a boiler to solve a problem which you -- or whoever installed your equipment -- created for yourself. Not a very productive approach...
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • rick in Alaskarick in Alaska Posts: 982Member
    Would for sure look at the System 2000 Ek frontier. Another one might be the Burnham LE series.
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