Click here to Find a Contractor in your area.
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/.

How do I explain this...

Tom_133
Tom_133 Member Posts: 720
So I am doing a job for a 30 year plumber, this job includes snowmelt. Here is the design for the snowmelt when done properly.



The problem is he decided to go 12" centers and only put 2 loops in!!! Yes, its poured.

Here is the numbers I am getting trying to fudge it as much as possible.






Manifold 1 is the ramp and Manifold 2 is the connector, also keep in mind the ramp hasn't been poured yet so thats going to be right.

Seriously, how do can I explain to a 30 year plumber that we need to break up the concrete and start again on his dime because it wont work?
Most of all I am curious how you guys illustrate/explain less tubes means greater head??

Tom
Montpelier Vt

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,522
    You can explain it to him will he listen? Depends if he is a know it all or not.

    With the same flow rater smaller pipe=less tubes=greater head
  • hot_rod
    hot_rod Member Posts: 14,552
    Maybe try to explain it as BTU/ sq ft. Or the different ASHRAE classes of snow melt.

    Is it just the 500' that you are concerned about design calling for 5- 300" loops, 93,000 load? If so 186 BTU/ sq. ft. that is a fairly hefty system. Is it a critical application, b building entry? Hospital pad? Insulated below and edges?

    2 loops of 5/8, 300'? You could work it backwards and show how many BTU that system is capable of. less than 1/2 of what is expected, possibly.

    Was there a design criteria based on the class 1,2 or 3?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Tom_133
    Tom_133 Member Posts: 720
    Its the connector for 2 parking areas in a senior center. I havent seen if it will somewhat covered, or completely open to the weather. As for the class, I am not sure of that either. I will look into it. I was hoping for a good illustration that explains more tube less head. Thats what he is missing.
    Tom
    Montpelier Vt
  • ratio
    ratio Member Posts: 2,727
    Maybe a cross section of the pipes, visually showing the flow area?
  • hot_rod
    hot_rod Member Posts: 14,552
    changes to head is related to tube diameter, circuit or loop length, flow rate, type of fluid, etc.
    SIM like radiant output is based on the amount of heat BTUs per square foot, regardless of how you get it there.

    The wide spacing will be a challenge, typically 6- 8". And inadequate loops will make it hard to get the output of 186 btu/ sq ft. if that is the expectation.?

    That being said, it will work to some degree, slowly and with some striping. It comes down to expectation for the customer. And amount of snow or ice expected :)

    A neighbor in the mountains has 12 PB in his drive with a 40 gallon gas water heater! Slow but steady and inexpensive to install :)

    Idronics 12 explains how energy moves in a liquid and all the relationships of heat transfer.

    https://www.caleffi.com/sites/default/files/file/idronics_12_na_2019.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    PC7060
  • Jamie Hall
    Jamie Hall Member Posts: 15,350
    For some reason, explaining the relationship between head loss, pipe (or pipes!) diameter (and fittings), and flow has always seemed to be difficult for many people to grasp. Confounding the problem is that for almost all the work we do around here, we rarely have a truly constant head source to play with -- and throwing a pump and pump curve into the puzzle doesn't help any.

    I've sometimes noted faint glimmers of understanding when it comes to multiple pipes in parallel, though, with comparing it to a superhighway with one, two, three or fours lanes and how many cars can go by...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    GroundUp
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 628
    Maybe this is another application for a timed 3 way valve that can reverse flow in the loop to even out the heat delivery.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
    mattmia2
  • Zman
    Zman Member Posts: 6,438
    I like the original design better and the plumber should have followed the design.
    That being said, I see a ton of poorly designed snowmelt systems and would give the original design a, "A" and what the plumber did a "B-". It will melt snow pretty well. You will see a bit more striping on startup but it will get the job done.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Tom_133
    Tom_133 Member Posts: 720
    So, just an update. It turns out the GC shrunk the pad almost in half. Its now 290sqft with 2 loops of 5/8" tube 300' long. So I didnt have to explain anything to him. The best part of this is I learned a lot about snowmelt design. Thanks all
    Tom
    Montpelier Vt
  • hot_rod
    hot_rod Member Posts: 14,552
    Tom_133 said:

    So, just an update. It turns out the GC shrunk the pad almost in half. Its now 290sqft with 2 loops of 5/8" tube 300' long. So I didnt have to explain anything to him. The best part of this is I learned a lot about snowmelt design. Thanks all

    That's workable
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
Sign In or Register to comment.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!