• Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • CONTRACTORS
  • ENGINEERS
  • RADIANT & HYDRONICS
  • INSIGHTS
  • MEDIA
  • RESOURCES
  • EMAGAZINE
  • SIGN UP!
cart
facebook instagram twitter linkedin youtube
  • CONTRACTORS
  • BATH & KITCHEN PRO
  • BUSINESS MANAGEMENT
  • HIGH EFFICIENCY HOMES
  • TECHNOLOGY
  • WATER TREATMENT
  • PMC COLUMNS
  • PMC COLUMNS
  • Dave Yates: Contractor’s Corner
  • John Siegenthaler: Hydronics Workshop
  • Kenny Chapman: The Blue Collar Coach
  • Matt Michel: Service Plumbing Pros
  • Scott Secor: Heating Perceptions
  • ENGINEERS
  • CONTINUING EDUCATION
  • DECARBONIZATION | ELECTRIFICATION
  • FIRE PROTECTION
  • GEOTHERMAL | SOLAR THERMAL
  • PIPING | PLUMBING | PVF
  • PME COLUMNS
  • PME COLUMNS
  • Christoph Lohr: Strategic Plumbing Insights
  • David Dexter: Plumbing Talking Points
  • James Dipping: Engineer Viewpoints
  • John Seigenthaler: Renewable Heating Design
  • Lowell Manalo: Plumbing Essentials
  • Misty Guard: Guard on Compliance
  • RADIANT & HYDRONICS
  • RADIANT COMFORT REPORT
  • THE GLITCH & THE FIX
  • INSIGHTS
  • CODES
  • GREEN PLUMBING & MECHANICAL
  • PROJECT PROFILES
  • COLUMNS
  • SPONSOR INSIGHTS
  • COLUMNS
  • Codes Corner
  • Natalie Forster: Editorial Opinion
  • Guest Editorial
  • MEDIA
  • PODCASTS
  • VIDEOS
  • WEBINARS
  • RESOURCES
  • INDUSTRY CALENDAR
  • DIRECTORIES
  • EBOOKS
  • PM BOOKSTORE
  • CE CENTER
  • MARKET RESEARCH
  • CLASSIFIEDS
  • EMAGAZINE
  • EMAGAZINE
  • ARCHIVE ISSUES
  • CONTACT
  • ADVERTISE
  • PME EMAGAZINE ARCHIVES
search
cart
facebook instagram twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • CONTRACTORS
    • BATH & KITCHEN PRO
    • BUSINESS MANAGEMENT
    • HIGH EFFICIENCY HOMES
    • TECHNOLOGY
    • WATER TREATMENT
    • PMC COLUMNS
      • Dave Yates: Contractor’s Corner
      • John Siegenthaler: Hydronics Workshop
      • Kenny Chapman: The Blue Collar Coach
      • Matt Michel: Service Plumbing Pros
      • Scott Secor: Heating Perceptions
  • ENGINEERS
    • CONTINUING EDUCATION
    • DECARBONIZATION | ELECTRIFICATION
    • FIRE PROTECTION
    • GEOTHERMAL | SOLAR THERMAL
    • PIPING | PLUMBING | PVF
    • PME COLUMNS
      • Christoph Lohr: Strategic Plumbing Insights
      • David Dexter: Plumbing Talking Points
      • James Dipping: Engineer Viewpoints
      • John Seigenthaler: Renewable Heating Design
      • Lowell Manalo: Plumbing Essentials
      • Misty Guard: Guard on Compliance
  • RADIANT & HYDRONICS
    • RADIANT COMFORT REPORT
    • THE GLITCH & THE FIX
  • INSIGHTS
    • CODES
    • GREEN PLUMBING & MECHANICAL
    • PROJECT PROFILES
    • COLUMNS
      • Codes Corner
      • Natalie Forster: Editorial Opinion
      • Guest Editorial
    • SPONSOR INSIGHTS
  • MEDIA
    • PODCASTS
    • VIDEOS
    • WEBINARS
  • RESOURCES
    • INDUSTRY CALENDAR
    • DIRECTORIES
    • EBOOKS
    • PM BOOKSTORE
    • CE CENTER
    • MARKET RESEARCH
    • CLASSIFIEDS
  • EMAGAZINE
    • EMAGAZINE
    • ARCHIVE ISSUES
    • CONTACT
    • ADVERTISE
    • PME EMAGAZINE ARCHIVES
  • SIGN UP!
Columns

Return of Off The Wall

By Dan Holohan
August 1, 2011

Dan Holohan’s website, www.heatinghelp.com, includes a message board called “The Wall.” Regular participants include some of the brightest and most dedicated practitioners of hydronic and radiant heating in North America. As a result, the useful information found here rivals that found on any online forum in the industry.

With Dan’s return to Plumbing & Mechanical, Supply House Times and PM Engineer (pme), we are again sharing with readers, with Dan’s permission, some of the posts (edited by PM staff for style and grammar) that pertain to technical problems in the field or other items of interest.

Replacement boiler sizing

Original inquiry: Replacing an old HB Smith 25 mills, 6-section boiler (1,600 square feet steam). Existing installed radiation only measures 503 square feet. Two stores on the ground floor have been disconnected. However, the supply piping is still there serving 14 small radiators on the upper floors. Do I trust the new boiler rating of 540 square feet or do I need to go up a size due to the large supply pipe sizing in basement? Also, just to throw something else into the mix: Is there any difference in boiler quality or steam supply if the boiler riser requirement is one at 3 inches or two at 2 inches? HeatJockey


Replies: I have run into this situation before and it can leave you scratching your head for the correct answer. First, are the disconnected stores ever going to be reconnected? That is the million-dollar question. If so, you have to calculate that load into the replacement boiler. If not, then I would size to the existing load, then add for pickup and piping loss of about 15 percent. That would leave you with needing approx. 600 square feet. Also, insulate those mains and check all vents or traps.
As far as the risers go, I always would go with a boiler with two risers, keeping the exit velocity low and avoiding the possibility of a tipped water line. GregMaxwell

Going up a size is more comfortable than cutting it close with a good customer. Reassurance from someone else stops the “Am I being an idiot?” feeling. HeatJockey

Have you done a heat loss? Even a quick heat-loss calculation will help. You don’t have to heat up the entire radiator if the radiator is larger than you need. Quite often I go smaller than the connected load if the heat loss is much smaller than the connected load. If the heat loss is larger than the connected load, you go larger and plan on adding radiators.
You do always have to take into account that the supply steam piping was sized for all of the original radiators. Paul

The boiler with one 3-inch has the lower steam velocity. You can figure the area of a circle. One 3-inch is larger than two 2-inch circles. Point odds to 6 point odds, so roughly a 15 percent increase in volume on the pipe.
The 3-inch requires big wrenches, threaders and more sweat. The 2-inch is easier for the light-duty shop and is almost large enough to do the job. Now two  2 1/2-inch risers are better than one 3-inch riser. Charlie from wmass

Do we always need to fill the radiators with steam? That will certianly provide adequate heat, but you will be oversizing the boilers more times than you think for the simple reason the steam system was oversized to begin with because of the foul-air issue. The original radiators may have been oversized by 30 percent.
Varivents will shut down the boiler and prevent overheating, but you may get short- cycling on certain jobs. On small buildings, this does not matter that much. On a bigger building it matters a lot. Right now, I’m estimating a job where the engineer specified a 6,000,000 Btu boiler when a 4,000,000 will do just fine. Can you imagine the cost difference on this job? Paul

Paul, the correct answer is no, we do not need to fill every radiator to heat the building properly on most days. We need to fill every radiator on design days. Also remember if the radiators are in rooms below 70 degrees F, they will call for more steam to heat across as the effective square footage per section increases the lower the room temp gets. Customers also will find the radiator that does not warm across and call you out on it, even if the fuel bill drops and the building is perfectly comfortable. Charlie from wmass

Links

  • The Wall at HeatingHelp.com
  • Contact Plumbing & Mechanical

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Holohan

Dan Holohan and his wife, Marianne, founded www.heatinghelp.com in 1997. You can reach Dan Holohan at dan@heatinghelp.com. He loves hearing from you!

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • Worker using the Milwaukee Tool SWITCH PACK drain cleaner

    Pipeline profits: Drain cleaning, pipe inspection create opportunities

    Drain cleaning and inspection services offer lucrative...
    Plumbing News
    By: Nicole Krawcke
  • Uponor employee, Arturo Moreno

    The reinvestment in American manufacturing and training

    Plumbing & Mechanical Chief Editor Nicole Krawcke and...
    Plumbing News
    By: Nicole Krawcke and Natalie Forster
  • March 2024 Women in Plumbing hero image of woman engineer overlayed by circle of hexagon shapes with numbers from 1 to 10

    Celebrating 10 Influential Women in the Plumbing Industry

    Celebrating Women's History Month and Women in...
    Plumbing News
    By: Nicole Krawcke
close

1 COMPLIMENTARY ARTICLE(S) LEFT

Loader

Already a Registered User? Sign in now.

Subscribe For Free!
  • eNewsletters
  • Online Registration
  • Subscription Customer Service
  • eMagazine
  • Manage My Preferences

Bell & Gossett Illustrates Path to Net-zero at AHR Expo

Bell & Gossett Illustrates Path to Net-zero at AHR Expo

NIBCO Press Solutions

NIBCO Press Solutions

AI can boost efficiency and profitability for plumbing, HVAC contractors

AI can boost efficiency and profitability for plumbing, HVAC contractors

IPEX celebrates grand opening of new Florida distribution center

IPEX celebrates grand opening of new Florida distribution center

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the Plumbing & Mechanical audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of Plumbing & Mechanical or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • J.J. Keller CMV vehicles on road
    Sponsored byJ. J. Keller & Associates, Inc.

    The dash cam game-changer for small business safety

Popular Stories

The interior of a government building.

President Trump signs executive order promoting skilled trades and apprenticeships

Underfloor heating installation with drain sewer hole in bathroom close up on water floor heating.

Using hydronics to leverage time-of-use electrical rates

Watts Nexa mobile image

Behind the Wall: Where smart plumbing gets smarter

PMCE Home-X April 29 Free Webinar: From Legacy to Leadership: Preparing Your Home Services Business for the Next Generation

Events

November 13, 2024

Future Proofing MEP: Navigating the 2026 High Efficiency Water Heating Standards

Join our deep dive into DOE’s new standards so you can future-proof your MEP practice.

EARN: 0.1 ASPE CEU; 1 AIA LU/HSW; 0.1 IACET CEU*; 1 PDH

View All Submit An Event

Poll

Will business be up or down in 2025?

Do you anticipate business in 2025 to be up or down in comparison to 2024?
View Results Poll Archive

Products

The Water Came To A Stop

The Water Came To A Stop

See More Products

Download the FREE Water Conservation, Quality & Safety eBook: Plumbing Trends Increasing Safe Water Availability

Related Articles

  • Off The Wall: Steam boilers and wet returns

    See More
  • Off The Wall: Cloudy hot water

    See More
  • Holohan

    Dan Holohan: Does periodically turning the boiler off actually save money?

    See More

Related Products

See More Products
  • The ACCA Job Safety (1).jpg

    The ACCA On-The-Job Safety Handbook (Pack of 5)

  • what hydronics taught holohan.jpg

    What Hydronics Taught Holohan: A Memoir of Life in the Heating Industry

  • lost art steam heating.jpg

    The Lost Art of Steam Heating Revisited

See More Products
×

Keep your content unclogged with our newsletters!

Stay in the know on the latest plumbing & piping industry trends.

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
    • Supply House Times
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletter
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • Instagram
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

search
cart
facebook instagram twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • CONTRACTORS
    • BATH & KITCHEN PRO
    • BUSINESS MANAGEMENT
    • HIGH EFFICIENCY HOMES
    • TECHNOLOGY
    • WATER TREATMENT
    • PMC COLUMNS
      • Dave Yates: Contractor’s Corner
      • John Siegenthaler: Hydronics Workshop
      • Kenny Chapman: The Blue Collar Coach
      • Matt Michel: Service Plumbing Pros
      • Scott Secor: Heating Perceptions
  • ENGINEERS
    • CONTINUING EDUCATION
    • DECARBONIZATION | ELECTRIFICATION
    • FIRE PROTECTION
    • GEOTHERMAL | SOLAR THERMAL
    • PIPING | PLUMBING | PVF
    • PME COLUMNS
      • Christoph Lohr: Strategic Plumbing Insights
      • David Dexter: Plumbing Talking Points
      • James Dipping: Engineer Viewpoints
      • John Seigenthaler: Renewable Heating Design
      • Lowell Manalo: Plumbing Essentials
      • Misty Guard: Guard on Compliance
  • RADIANT & HYDRONICS
    • RADIANT COMFORT REPORT
    • THE GLITCH & THE FIX
  • INSIGHTS
    • CODES
    • GREEN PLUMBING & MECHANICAL
    • PROJECT PROFILES
    • COLUMNS
      • Codes Corner
      • Natalie Forster: Editorial Opinion
      • Guest Editorial
    • SPONSOR INSIGHTS
  • MEDIA
    • PODCASTS
    • VIDEOS
    • WEBINARS
  • RESOURCES
    • INDUSTRY CALENDAR
    • DIRECTORIES
    • EBOOKS
    • PM BOOKSTORE
    • CE CENTER
    • MARKET RESEARCH
    • CLASSIFIEDS
  • EMAGAZINE
    • EMAGAZINE
    • ARCHIVE ISSUES
    • CONTACT
    • ADVERTISE
    • PME EMAGAZINE ARCHIVES
  • SIGN UP!