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.
If our community has helped you, please consider making a contribution to support this website. Thanks!

The Hidden Hydronic Problem Nobody Checks: Water Velocity

Options
RayWohlfarth
RayWohlfarth Member Posts: 2,029
edited June 8 in Strictly Steam

This week's video talks about why the speed of the water in a hydronic system matters. Too slow and the air gets trapped. Too fast and you get noise and eventually leaks.

Ray Wohlfarth
Boiler Lessons
JohnNY

Comments

  • hot_rod
    hot_rod Member Posts: 27,784

    Nice job on this case, Ray. The graphics, length of the presentation all work well.

    You left us hanging at the end, :) "ask yourself one simple question, how fast is the water moving"

    How about a part 2 how to determine flow velocity in hydronic systems?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JohnNY
    JohnNY Member Posts: 3,391

    I would really appreciate it, Ray, if you would develop an ultrasonic flow meter that wholesales for about $500.

    Ever try to buy one of those? They're insanely expensive but I'll bet they answer a lot of questions.

    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
    Classes
    GGross
  • Intplm.
    Intplm. Member Posts: 3,076

    We had what was thought to be a small case of velocity erosion on a new commercial building. Upon removing the leaking piping, it was discovered that the leak was caused by visible pipe wall erosion. Much like a riverbank looks after a heavy rain. Obvious erosion.

    Over a span of a few years, small erosion issues would arise from time to time.

    What we did to correct this was to add Variable Frequency Drives (VFD) to the heating systems' circulators, as well as microbubble air separators. This was done some thirty-plus years ago, and the results are still proving successful to this day.

    I haven't seen much on velocity issues, but they certainly need to be considered. They are not always obvious and can cause a lot of headaches.

    @RayWohlfarth Thanks for this video. It is a very helpful subject.

    TMS1980
  • jumper
    jumper Member Posts: 2,581

    HydronicsHandbook from 60+ years ago said 6 fps max as I recall. Decades later plumbing engineers told me that 3 fps is safer. There's a difference between HHW and chilled glycol mix. And between different pipe materials. Ideally one determines system curves (plural intentional) with a variable speed pump and then a fixed speed pump is chosen. Set it and forget it. If you don't want burner to cycle too often then you need some method to maintain minimum flow.

  • HydronicMike
    HydronicMike Member Posts: 365

    My buddy bought these used on ebay for about $150 each. They are getting harder to find. Covers 1/2"-3/4" and 1"-1 1/4"). He added rechargeable battery pack, some wires/connectors, and a harbor freight case.

    Image (3).jpg
    JohnNY
  • Steamhead
    Steamhead Member Posts: 18,665

    All Steamed Up, Inc.

    Baltimore, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting