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Condensing boiler Q. (Munchkin?)

JohnNY8
JohnNY8 Member Posts: 33
What is the advantage to piping primary/secondary loops when using a condensing boiler?

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Comments

  • clammy
    clammy Member Posts: 3,150
    p/s

    On a boiler like a munchkin it is mostly because of the high pressure drop across the units heat exchanger and to ensure you have enough flow through the boiler to make the pressure switch .I have 1 munchkin install out there and it running great using there vision one reset great set up just follow there sugestion and you'll have no promblem i used a 007 for the boiler pump and a 0010 for the indirect and 1 007 for 3 baseboard zones and one for a small radiant garage zone with the modulating this unit really does cut gas comsumption and increase comfort .I sized my baseboard for a max 160 temp which it hardly goes to excellent set up i,m waiting for the buderus gb142 to install in my own home peace and good luck clammy

    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating

  • .
    . Member Posts: 80


    The Munchkin has very small-bore coils, with flow resistance equivalent to hundreds of feet of 3/4" copper tubing. When you have that situation PLUS muliple zones, then the head across the boiler varies depending on how much flow is required (which depends on how many zones are calling for heat). So, how much flow you get in zone 1 depends on whether zone 2 is running and so forth. Using P/S piping means that each zone draws water from the closely spaced tees rather than the boiler, and there is no pressure drop across the closely spaced tees, and so the zones become independent.

    If you have only one zone, you don't need P/S piping. However, PS pumping will allow you to have different flow rates in the boiler and the house. Munchkin, for example, wants a specific flow rate through the boiler or its electronics gets confused. This flow rate may not be ideal for the house.
  • Rookie
    Rookie Member Posts: 175
    Buderus GB 142

    Do you guys use the isolation valves in between the close coupled tees? I have found that this make purging a snap, only need one outlet, in conjunction with valve isolating the boiler with unions will make that christmas eve replacement and testing a lot easier.
    Clammy post some pics when you get the Buderus installed, I just finished the manual it's about 100 pages jammed with information,the boys and I are heading to Buderus for some training in early March.
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Opened ended statement...

    "If you have only one zone, you don't need P/S piping."

    No, but you'll need one heck of a pump to overcome the pressure drop of the boiler AND the system, which are piped in series.

    Best bet is to follow the manufacturers recommendations.

    ME

  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Hide the valve handles...

    Anytime you are puting valves between seconday branches, remove the handles and put them underneath the cover of the boiler. No one ever looks in there...

    This will avoid you having some unknowing 1st year service technician coming in and looking at those valves, not understanding the operatings of a P/S system, closing the valve because it looked like it should be closed! This leads to scalding DHW, or extremely hot homes.

    Don't ask me how I know this happens...

    The other advantage of having the ball valves between the secondaries is that it CAN be used to provide temperairy heat/flow to a secondary circuit whose prime mover (pump) has failed. Been there, done that.

    Just make sure you remove and hide the handle when you're done.

    ME
  • Randy Tibbits
    Randy Tibbits Member Posts: 91


    That's a nice looking job. Those taco pumps on the righthand side might need to be turned 90 degrees. Not sure about taco but grundfos wants their pumps installed with the motor horizonal.
  • Mad Dog
    Mad Dog Member Posts: 2,595
  • Rookie
    Rookie Member Posts: 175
    Taco wrong way

    You are right I never went back to change that system ( circulators) I did it 1999,funny never had a compaint, if I remember Taco circulator if placed in that position I think needs to operate above 20 psi, don't quote me on that, I place all my circulators on the horizontal now. I like primary secondary, I hardly ever use zone valves except for the small two zone systems.
    Had the name Rocky from high school, there was a certain movie released and I just happened to become involved in a hockey game brawl , somehow I was label the instigator, funny name for an Irish kid from western mass.
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