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New boiler

gobucks823gobucks823 Posts: 5Member
I'm getting ready to replace my old boiler. New boiler is most likely going to be a Vitodens 200. My existing primary secondary loops are 1" while the supply and return on the new boiler are 3/4". Any issues with keeping the existing piping and just reducing to 3/4 at the boiler?

Comments

  • IronmanIronman Posts: 5,082Member
    That would depend on how btu's you're transferring between p/s, the gpm, and the delta T.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • gobucks823gobucks823 Posts: 5Member
    The new, smaller btu boiler can meet the demand according to the heat loss that was done. What issues can I run into if I leave the p/s as is at 1"?
  • IronmanIronman Posts: 5,082Member
    Again, btu's, gpm and delta T are the factors needed. In fact, if you'll give the btus, we can use assume a standard 20* delta T and calculate the gpm from that. Then we'll know what size piping is required.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • gennadygennady Posts: 740Member
    You need to check flow/ pressure drop of piping. Boiler connection size has nothing to do with piping size. How do you know current sizes are right?
    Gennady Tsakh



    Absolute Mechanical Co. Inc.

    www.AbsoluteMechanicalCoInc.com
  • ZmanZman Posts: 4,969Member

    I'm getting ready to replace my old boiler. New boiler is most likely going to be a Vitodens 200. My existing primary secondary loops are 1" while the supply and return on the new boiler are 3/4". Any issues with keeping the existing piping and just reducing to 3/4 at the boiler?

    What size is the new boiler?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rodhot_rod Posts: 11,608Member
    no problem having a 1", even if it is oversized a bit for actual the load.

    Same with hydro seps, no harm in oversizing, other than cost.

    I think you are saying the current piping, loop and secondaries is 1", the boiler has 3/4 connections?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • The Vitodens installation instructions can be difficult to absorb, but all the important facts you need are there. If you have trouble with any of it, call Viessmann.
    Where are you located?
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
  • gobucks823gobucks823 Posts: 5Member
    > @hot_rod said:
    > no problem having a 1", even if it is oversized a bit for actual the load.
    >
    > Same with hydro seps, no harm in oversizing, other than cost.
    >
    > I think you are saying the current piping, loop and secondaries is 1", the boiler has 3/4 connections?

    Yes that's correct. Rather than go through the expense of replacing the current p/s piping.
  • gobucks823gobucks823 Posts: 5Member
    I'm in Ohio. The new boiler is the 100k btu model.
  • ZmanZman Posts: 4,969Member

    I'm in Ohio. The new boiler is the 100k btu model.

    1" would be perfect for that boiler.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • gobucks823gobucks823 Posts: 5Member
    Zman said:

    I'm in Ohio. The new boiler is the 100k btu model.

    1" would be perfect for that boiler.
    Thanks.

    Another question....is the Viessmann motorized 3 way valve the only brand of valve that is compatible with the Vitodens 200 or will other brands work also?
  • ZmanZman Posts: 4,969Member
    There are a whole ton of mixing valve configurations. I am sure it is possible to use and alternate.
    Someone who has done this might chime in. Unless you know for sure another valve will work, The safe bet is to get an OEM valve and be done with it.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Other brands will work.

    The Viessmann 3-way mixing valve and the control that works the mixing valve are all integrated together with the boiler and work extremely well. Totally worth the extra cost.
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
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