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Piping design help

styxplostyxplo Posts: 18Member

This is my initial layout design

Heat load is 55,000 btu/hr

The mixing valves are not thermostatic but are just mechanically mixing valves so they follow the ODR reset curve with no smarts.

All the common piping is 1" except at the buffer tank which is 1-1/4"
the secondary circuit branches are 3/4"

A few questions
-Over all, does it look like I have everything covered??
- Does the varable speed pump, stay on as long as the outside temp is below my enable temperature. The boiler is only monitoring the temp sensor in the buffer tank so it will only fire when the tank falls below the setpoint of the ODR controller.
- what kind of check valves do I need in the panel radiator circuit because it doesn't have zone valves
- do I need balancing valves
- with the dirt mag separator do I still need a strainer
- Do I need a third pump in the secondary or is the pump at the outlet of the buffer tank work for the whole secondary side

Thanks Mark


  • hot_rodhot_rod Posts: 12,538Member
    I would make the buffer tank piping as large as possible, that piping section becomes a hydraulic separator for the 2 circulators, 2 FPS velocity in that section with the total system gpm flowing.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • styxplostyxplo Posts: 18Member
    ok. The inlet and outlet of the buffer tank are tapped at 1-1/4" so I was going to stick to that up until it branches off the tee's to 1" I've read that I should have the tee's at the tank as close as possible to the tank. Does that seem reasonable
  • hot_rodhot_rod Posts: 12,538Member
    Yes, close nipple your tees to the tank should work. 1-1/4 X1X1 tee.

    If you have any length like the drawing shows it wouldn’t hurt to upsize
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • styxplostyxplo Posts: 18Member
    ok. I am going to keep it as close as possible, but on your recomendation i will upsize it to 1-1/2" or even 2". better safe then sorry and from what I gather it won't hurt to be oversized.

    I made an updated drawing. The program is flaky on my laptop for some reason so I drew it as best I could.

    I originally chose zone valves and balancing valves because I thought it would be less expensive....turns out its almost $90 more expensive then pumps so I'm going with pumps

    I also answered a few of my own questions. The variable pump will basically go into an idle mode until one of the TRV opens and allows flow and it has a check valve built in to prevent reverse flow when that circuit is idle

    no strainer with the dirtmag.

    and I think I have the pumps figure out and the location correct??

    Any input or advice is greatly appreciated. I've got a lot of time invested in reading and researching, but I don't have real world experience like the people on this forum. I'm about to pull the trigger on purchasing my supplies and I won't to make sure I'm on the right track

    Thanks again Mark

  • hot_rodhot_rod Posts: 12,538Member
    Short fat piping at the tank.

    Need to pump out of the MIX port on 3 way thermostatic valves.

    Be sure you have checks in all circs
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
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