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Best Place for Circulator and Expansion tank

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Mail4tommo
Mail4tommo Member Posts: 23

Where would the best location be for the circulator and expansion tank in this primary secondary set up? A or B for the circ? and the circ after the expansion tank I know that . Im just confused

Thank you

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 27,237

    Unless the boiler has one inside, you need pumps at both locations. And in that case, probably the better location for the tank would be on the inlet side of the pump at B. That would also be your pressure reducing valve location.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Mail4tommo
    Mail4tommo Member Posts: 23

    @Jamie Hall so three pumps?

  • Mail4tommo
    Mail4tommo Member Posts: 23

    So the inlet side of b because the one on the zone circuits using (zone valves) and before B both would be technically pumping away from the tank correct?

  • Jamie Hall
    Jamie Hall Member Posts: 27,237
    edited February 10

    I misread your drawing. My error, and I apologise. I see now that there is a pump shown on the zone manifold. You need one other pump, and it could be at either A or B — doesn't matter unless the boiler has a high head loss, in which case B would be the preferred location, pumping away from both the boiler and the expansion tank.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Mail4tommo
  • hot_rod
    hot_rod Member Posts: 27,329

    there are a number of ways to pipe a PS system

    This shows the distribution loop as the primary, as it has the expansion tank connection.

    The large pipe size, pink line, becomes the reference for the boilers circulator to the expansion tank.
    It could be a single zone, multiple circs or one circ and zone valves on the distribution

    This is a 6 zone with circulators example.

    IMG_1443.jpeg
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Mail4tommo
  • Mail4tommo
    Mail4tommo Member Posts: 23

    Ok, just wanted to confirm how I planned it. Makes sense at B if high head loss. Appreciate it. Thanks @Jamie Hall

  • HomerJSmith
    HomerJSmith Member Posts: 2,774
    edited February 10

    I don't think your drawing is correct. The side ports on your tees should be on the boiler side not the distribution side. You need a pump on the boiler circuit and a pump on the distribution side if zoning with zone valves. @hot_rod diagram.

    image.png

    To your Ex tank question, It really doesn't matter. If it is on the distribution side, just make sure that the pump is pulling from the Ex tank. Same if the tank is on the boiler side

    The air eliminator should be on the boiler side on hot water from the boiler to the distribution side and the boiler pump should be pumping into the boiler intake.

    image.png

    I'm assuming it's a Mod/Con.

    Mail4tommo
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,035

    I would make the system loop the primary loop by placing the expansion tank on the section of the system loop down stream of the closely spaced tees. As shown here:

    Screenshot 2026-02-09 at 9.36.38 PM.png

    The loop with the expansion tank is the primary loop. I would also place a air seperator on that pipe where the expansion tank is located and also place the water feed connection at the expansion tank location. Ask me why if you need to know.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Mail4tommoRich_49
  • hot_rod
    hot_rod Member Posts: 27,329

    yet another option, you want the air purger close to the hottest temperature

    IMG_1963.jpeg

    The first option a few posts up makes for a nice clean piping arrangement, boiler “injects” heat into the primary loop

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Mail4tommo
  • Mail4tommo
    Mail4tommo Member Posts: 23

    @HomerJSmiththanks homer for taking your time

    @EdTheHeaterMan Thank you for taking the time to recreate my drawing . And yeah the separator is at the hottest point and (if possible @ the highest) because the higher the temp the more oxygen you get out of solution.

    @hot_rod Thank you as well, Appreciate it love the napkin drawing. Know my only question is to as why the circ is on the return in @EdTheHeaterMan drawing ? (maybe going off the assumption this is a high head boiler[Mod con]?? which it is a cast iron.

    and why @hot_rod your circ is on the boiler loop? Just some clarification here. I know they will both work but whats the reasoning?

    My plan is going with the paper drawing, even though it would be a cleaner look with @EdTheHeaterMan drawing

  • Mail4tommo
    Mail4tommo Member Posts: 23

    @hot_rod Just noticed it wasn't a napkin, my eyes are getting tired Apologies.

    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,035

    @Mail4tommo the boiler is the primary loop in the napkin drawing since the expansion tank is on the boiler loop. That is a perfectly good way to do the job with a cast iron boiler.

    Would you like me to draw it for you? give me the brand and model of the boiler and I will even match the colors. Taco Pump will be green, B&G pumps will be red and Grundfos pumps will be burgundy … generic pumps are blue!

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Larry Weingartenbjohnhy
  • Mail4tommo
    Mail4tommo Member Posts: 23

    @EdTheHeaterMan I appreciate it Ed , I'll make it on this one. You guys are the best truly!

    EdTheHeaterMan