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Boiler Install Questions?

Redduc97
Redduc97 Member Posts: 15
Looking for some opinions/suggestions on the piping layout I designed for a new install. Is there anything fundamentally wrong? (The indirect will be installed in the future). The boiler loop is 1" copper and the secondary loop is 3/4" copper for the zones after the
1 1/4" black iron headers.

Is there a recommended distance from the hydraulic separator to the first zone on the header?( I know there is a rule of thumb when using closely spaced tees) I planned on a short piece on the supply header to create an off set for the return piping.

Should the zone with the largest BTU requirement be located on the last branch and the smallest zone be on the first branch from the separator?

Not shown on the drawing are isolation valves for each pump as well as purge valves on the zone return lines.

any insight will be appreciated.

Comments

  • hot_rod
    hot_rod Member Posts: 14,786
    Looks fine, no min. piping distance as long as the headers are sized for total flow gpm. no issue with where the connections are regards to load size.
    Some installers prefer the indirect right off the boiler, and some boilers now have extra connections for that. if piped off the sep, size the indirect circulator to flow as much as the boiler can supply. Ideally the same gpm so flow is straight across the sep without any blending.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    fenkelSTEVEusaPA
  • Zman
    Zman Member Posts: 6,565
    edited January 18
    If you want to do outdoor reset on the heating side and domestic priority, I would pipe the indirect off the boiler and let the boiler control it. If you are running this "old school" at a fixed temp, this will work fine.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Redduc97
    Redduc97 Member Posts: 15
    Zman-
    I have a 50 gal gas fired water heater currently where I show the indirect so I thought it would be an easier swap out if I kept the indirect in that location.(the water heater is only a year old so I wasn't planning on replacing it right away). I was planning on using a Taco 4-zone switching relay with domestic priority to control the indirect circulator. Are you saying I should pipe the indirect off of the boiler loop and control the indirect circulator from the boiler? I am planning on using outdoor reset.
  • Ironman
    Ironman Member Posts: 6,367
    Mod/con boilers come setup for the connection of an indirect. They have low voltage terminals for the connection of the tank’s aquastat or sensor and high voltage terminals for the connection of the indirect’s pump. They will override their ODR feature when heating domestic.

    The way you’re showing it is for an old school cast iron boiler that has no provision for an indirect. Unless you use a pump control that has a separate end switch for the priority zone, there’s no way to override the ODR set point during a domestic call. In other words, you may only be getting 120* water to heat the indirect instead of 180* supply water.

    Do it the way the mod/con manufacturer shows in their manual (described above) or else you’ll make it more complicated than necessary and defeat what they’ve already built in to the boiler.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Zman
    Zman Member Posts: 6,565
    Like he said ^^^^^
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Redduc97
    Redduc97 Member Posts: 15
    Here is the switching relay I was planning on using. It appears it has an end switch for the indirect to allow the proper override of the outdoor reset so the boiler would provide 180* water to the indirect. Now the question is the location of the indirect piping? If I pipe it per the manufactures recommendation the indirect pump would be sized for the flow requirement of both the indirect and the boiler? The primary circulator would not operate during domestic priority calls.
  • Ironman
    Ironman Member Posts: 6,367
    Correct.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Redduc97
    Redduc97 Member Posts: 15
    Thank you for your insight and suggestions. I have started the install per my drawing (see attached). Once I locate the boiler circulator there will be about 4" of pipe between the isolation flange and the elbow at the boiler return. Should I allow for a longer piece of straight pipe before the elbow? Is there a rule of thumb for this?



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