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New boiler

gobucks823gobucks823 Member Posts: 20
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 Member Posts: 5,641
    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 Member Posts: 20
    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 Member Posts: 5,641
    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.
    mattmia2
  • gennadygennady Member Posts: 781
    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 Member Posts: 5,831

    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 Member Posts: 13,318
    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 Member Posts: 20
    > @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 Member Posts: 20
    I'm in Ohio. The new boiler is the 100k btu model.
  • ZmanZman Member Posts: 5,831

    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 Member Posts: 20
    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?
    gennady
  • ZmanZman Member Posts: 5,831
    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.
  • gobucks823gobucks823 Member Posts: 20
    So I got the new boiler installed, followed Viessmanns steps for filling, purging, startup, ect and the boiler will not fire. I've got the set point to 85 so it should cycle on. What the heck am I missing?
  • John RuhnkeJohn Ruhnke Member Posts: 880
    Is it in warm weather shut down mode?
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • John RuhnkeJohn Ruhnke Member Posts: 880
    The boiler needs to have water circulating through to trip the flow switch. If the line is air bound maybe its not circulating?
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • John RuhnkeJohn Ruhnke Member Posts: 880
    Is the boiler pump running? If not something isn't firing the boiler.
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • gobucks823gobucks823 Member Posts: 20
    Not in shutdown best as I can tell. I'm going to fall back and check purging again. Only thing I can come up with
  • John RuhnkeJohn Ruhnke Member Posts: 880
    Who sized the boiler loop circulator? Does the boiler circulate through the entire system? Or do you have a smaller boiler loop just for the boiler? If the circulator isn't strong enough to push through the boiler then the flow switch wont trip and the boiler wont fire. You need to not only have enough flow you need enough head pressure in the pump too.
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • gobucks823gobucks823 Member Posts: 20
    I think you nailed it John. I ran through the fill/purge again and let it run for a good 15 min and it fired so I must have had a slug of air in there.

    The boiler pump is a taco 0015e. Small boiler loop with the LLH
  • John RuhnkeJohn Ruhnke Member Posts: 880
    Sounds Good! Great Job!!

    Boiler Firing Day after a lot of hard work is one of the best days ever!!!
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • psb75psb75 Member Posts: 217
    I once forgot to set the date on a Viessmann 222-F commissioning. It wouldn't start up! Fussy, those Germans.
  • gobucks823gobucks823 Member Posts: 20
    I got my old tank out today and the new indirect installed. Works well. Only issue I'm running into is the heating zone pump is running constantly. Only way it shuts off is if I go into standby mode. It runs even when I'm in DHW only mode. I've got to have some coding screwed up somewhere. The boiler pump operates like it should. The DHW pump operates like it should also.
  • gobucks823gobucks823 Member Posts: 20
    When I got into information it shows the heating pump circuit is off but the pump is running. I'm assuming I've got the pump wire to the wrong switch. It's currently wired to the 28/20 slot
  • gobucks823gobucks823 Member Posts: 20
    So I figured out that the boiler is using the 28/20 for DHW recirc which I dont have. Manual refers to coding address 33 for using the heating pump with the 28/20 switch.
  • gobucks823gobucks823 Member Posts: 20
    edited September 2019
    Found it in level 2
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