Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

BYPASS PIPING

Options
jim f
jim f Member Posts: 182
in THE MAIN WALL
i would like to incorporate bypass piping in this
reverse return scenario. looking for ideas and inputs?? would you have two seperate bypass lines to each boiler or one common bypass off the headers??
searching for diagrams with no luck.
thanks in advance!!
jim f.
milford, ct.

Comments

  • jim f
    jim f Member Posts: 182
    Options
    real life

    heres a real life picture of the diagram i drew
  • Gary Fereday
    Gary Fereday Member Posts: 427
    Options
    \" ? \"

    How do you intend to run the boilers, together, & or seperately, say as demand increases? That is perhaps where to start.
  • Steve Q.
    Steve Q. Member Posts: 5
    Options
    By-pass piping

    The best approach to piping 2 boilers is to icorporate primary-secondary piping with pumps for each boiler and a staging control.(Tekmar can provide you with the one best suited for your needs. This drawing comes right out of one of Dan's books. He has a great book called primary secondary piping. Get it for future jobs.
  • Unknown
    Unknown
    Options
    Parallel Piping with Bypasses

    Jim,

    Here is a drawing of individual boiler bypasses with parallel piping. Hope this helps.

    Glenn Stanton

    Burnham Corp.
  • Mark J Strawcutter
    Mark J Strawcutter Member Posts: 625
    Options
    thermal shock

    Doesn't this run the risk of thermal shock and short cycling on the secondary boiler?

    Mark
  • jim f
    jim f Member Posts: 182
    Options
    thermal shock.

    thats why i would like to put bypass piping to each boiler.
  • Mark J Strawcutter
    Mark J Strawcutter Member Posts: 625
    Options
    two kinds of thermal shock

    bypass piping protects against thermal shock from cold return water hitting a hot boiler.

    The diagram posted showing each boiler as a separate secondary loop off a primary can have another kind of thermal shock - hot return water hitting a cold boiler.

    Mark
  • jim f
    jim f Member Posts: 182
    Options
    what if?

    what if both boilers were maintainer temp for indirect??
  • Mark J Strawcutter
    Mark J Strawcutter Member Posts: 625
    Options
    indirect or tankless?

    with indirect I don't think you'd be maintaining temp so shock would still be an issue

    if tankless coil in boiler, then you would probably be maintaining a min temp so this "reverse shock" would be less of a concern.

    Mark
  • Steve Q.
    Steve Q. Member Posts: 5
    Options
    Control Scheme?

    I'm not quite sure about Glen's piping diagram? It looks like your bypassing the boiler and lowering supply side temperature? Is this true? Glen could you explain?(No disrespect intended.) Do you intend to reset boiler temperature? Are there indirect water heaters?
  • Unknown
    Unknown
    Options
    Steve

    That is exactly what is happening with the piping. The flow from the return of the system is bypassing the boilers. This will reduce the amount of cooler return water the boilers may encounter. Jim's request was for bypassing piping for tandem boilers when piped in parallel. He is not stage firing the boilers in this case so there is no concern about reverse thermal shock or hot water hitting a cold boiler. The better way to pipe tandems is primary secondary injection, preferably with a way to monitor the return water temperature.

    Glenn
  • Steve Q.
    Steve Q. Member Posts: 5
    Options
    No stage firing?

    Why wouldn't he stage fire these boilers. With all those zones the heating demand has to be varied by quite a bit. Does it not pay to do this in this situation?
  • Howard
    Howard Member Posts: 57
    Options
    May I jump in?

    > i would like to incorporate bypass piping in

    > this reverse return scenario. looking for ideas

    > and inputs?? would you have two seperate bypass

    > lines to each boiler or one common bypass off the

    > headers?? searching for diagrams with no

    > luck. thanks in advance!! jim f. milford, ct.



    Based on your photo, let me propose a bypass pipe. It would look like a 7th zone just like the other 6 but would consist of a pump and a short circuit of pipe from supply to return. Run the circulator whenever the boilers fire. Comments??

    I'd be concerned about overheating a satisfied zone if water can run backwards through it when other pumps are running.

    I'm a service tech. I's a good day if I can help. I's a better day if I can learn.
  • Howard
    Howard Member Posts: 57
    Options
    May I jump in?

    Based on your photo, let me propose a bypass pipe. It would look like a 7th zone just like the other 6 but would consist of a pump and a short circuit of pipe from supply to return. Run the circulator whenever the boilers fire. Comments??

    I'm a service tech. I's a good day if I can help. I's a better day if I can learn.
  • Ward
    Ward Member Posts: 1
    Options
    BYPASS PIPING

    REFER TO WEIL MCLAIN MULTIPLE BOILER SYSTEMS. IT'S IN THERE COMMERCIAL BOILERS REFERENCE MANUAL. DIAGRAMS WILL GIVE ALL YOU NEED, AIR ELIMINATION, PRIMARY / SECONDARY PIPING AND CONTROLS FOR STAGING BASE ON LOAD. SOME REPIPING WILL BE REQUIRED BUT YOU'LL END UP WITH A VERY EFFICIENT SYSTEM WITH MINIMUM STANDBY LOSS. CHECK IT OUT.
  • jim f
    jim f Member Posts: 182
    Options


    any suggestions or input on howards post?
  • Unknown
    Unknown
    Options
    What you are describing

    is what we refer to as a shunt pump. It is an acceptable practice in the industry and is used quite often on larger jobs and boilers. The best strategy would involve an injection piping system with return water sensors to vary flow or divert flow with a variable speed pump or a 3 or 4 way diverter valve.

    Glenn Stanton

    Burnham Corp.
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Options
    Answers and Questions...

    In that order, attached is a drawing showing the ultimate primary secondary sytem with a thermostatic bypass incorporated to avoid cold shocking the boiler. Not quite how is would work for reverse thermo shocking, and not even sure that's a real issue.

    Now for the question, Why do boiler and water heater manufacturers still show "bull headed" tees in their hydronic piping configurations?

    One of the very first articles that the Grand Master of hydronic education, John Siegenthaler penned had to do with bull headed tees and why you SHOULDN'T use them.

    Here it is, many years later and numerous hydrponic heating equipment manufacturers are still showing their drawings with bull headed tees incorporated. Not that Siggy needs any more work, but it would be wise for these errant manufacturers to hire Master Siegenthaler and have him
    "update and upgrade" their mechancial drawings.

    The Munchkin folks hired him to do the design drawings for their newest installation manual on the Vision series boilers, and it looks great. Not that Brian French needed any help really, I've always been impressed with Brians parallel reverse return characteristics. Brian "gets it". Just like Siggy does.

    Come on guys, catch up. Yer giving us a bad name:-)

    NO MORE BULL HEADED TEES PLEASE!!!

    Happy Gobble Gobble day!

    ME

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
This discussion has been closed.

Categories