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.

Head loss Calculation - Pump Sizing - 1 pipe monoflo system

paul3x16
paul3x16 Member Posts: 4
edited November 6 in THE MAIN WALL

Hi, i need help

I'm trying to figure out the head loss. but i got lost lol.

Hydroterm Boiler - Input 95,000 BTU/HR - 76,000 BTU/HR

One loop system - not sure if its a monoflow system.

One Zone, Main loop 3/4 (60 linear ft), Branch out to cast iron radiators with 1/2 - total of 12 radiators assume 10ft off the main loop.

when i purchase the house they change the circulating pump. since then some radiators stopped heating up. they just get warm (the furthers ones). i feel like my taco 007 its too small. I'm in the process to replace it with a 010 or 014 but i can't figure out how to calculate the head loss.

image.png

according to Taco - my head loss is 21.

i did get the GMP 76,000/10,000 = 7.6GMP

but on this discussion that i found on this blog,

circulator sizing for 1 pipe monoflo tee system — Heating Help: The Wall

they also calculate the head loss on the main loop and the branch to radiators.

using their calculation main loop gives me 4.6 head loss and 4.94 head loss on the branch. total 9. but i know my taco 007 should be in range. but its not.

image.png

What PSI should my system have, 12PSI or 15PSI. it's a basement and a 1st floor

i recently change the Expansion tank. but i did not let some air out, i believe it comes at 40PSI.

Can someone help me PLEASEEEE

Comments

  • Big Ed_4
    Big Ed_4 Member Posts: 2,962

    Mono flow should be low head and high flow …. Volume is what you are looking for ..

    There was an error rendering this rich post.

    paul3x16
  • paul3x16
    paul3x16 Member Posts: 4

    ok perfect, Thank you.. how do i calculate the volume??

    another question. what PSI should i set my system to, 12PSI or 15PSI. its a basement (where the boiler is) and first floor.

    also i replaced the expansion tank, i just realize i never check the pressure of the expansion tank, i was reading that i need to lower the PSI to match my system.

  • Gilmorrie
    Gilmorrie Member Posts: 186

    Why was the pump replaced? It would be helpful to learn the model of the pump that was removed. If the system worked satisfactorily with that pump, that could be a starting point?

    What is the Btu rating of the boiler?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,212

    Need more information. Is the monoflow loop 60' out and back? You also need the EDR of all the radiation to determine the flow volume. And the branch piping to the rads is it 1/2" 10' out and back?

  • paul3x16
    paul3x16 Member Posts: 4
    edited November 6
    https://forum.heatinghelp.com/discussion/comment/1818456#Comment_1818456

    im trying to figure out what is the cause of some radiators not heating up. Before buying the house i was renting the same house. One day the pump failed, the owner replaced it. Since i was only renting i did not pay attention of the old pump. After that it’s when the radiators stop working. I don’t know if it might be the pressure on the system or the pump. And since i own the house now. Im trying to fix it.

    76,000 btu and current pump 007


    i called various technicians none of them wants to troubleshoot the problem. Their only option it’s to replace the boiler. The boiler it’s not leaking

  • Jamie Hall
    Jamie Hall Member Posts: 24,396

    t's not the boiler. Monoflow systems — if that's what it really is — are notoriously difficult to purge, and if there is air left in a radiator it just won't heat.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterManSuperTechhot_rodpaul3x16
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,035
    edited November 6
    https://forum.heatinghelp.com/discussion/comment/1818450#Comment_1818450

    Don't lower the factory pressure in the expansion tank. It should be factory charged at 12 PSI If it is lower than 12 PSI then you can add air pressure.

    As far as a one story home over a basement, 12 PSI is more than enough, but i would not lower it.

    And you want to be sure you have a one pipe monoflo® system to measure the pump head requirements. Look for these tee fittings

    Screenshot 2024-11-06 at 5.18.48 PM.png

    The one I circled looks like it could be a 3/4" thru with a 1/2" branch like you have described.

    @paul3x16 Said: One Zone, Main loop 3/4 (60 linear ft), Branch out to cast iron radiators with 1/2 - total of 12 radiators assume 10ft off the main loop.

    This tells me that you have only 40,000 BTU heat capacity on that one loop, and require only 4 gallons per minute for that loop (not the 10 GPM you indicate on your pump curve chart).

    That means your boiler is oversized for the system, unless you have a second loop on the same single zone thermostat. It is possible that you had a B&G 100 pump at one time, and for the most part a Taco 007 will do most jobs.

    If your system was a poorly designed monoflo® then the B&G 100 may have pushed a tad more flow rate, like maybe as much as 5 GPM. That may have been a little noisy but that noise may have been in 3/4" main pipe in the basement and was not transmitted to the first floor pipes.

    if you do not have tee fittings like the picture above for each radiator (or another brand of similar design that would have an arrow embossed on the side) then you may have series loop design.

    Here is the difference

    Screenshot 2024-11-06 at 5.26.06 PM.png

    Each red dot indicates a monoflo® tee and both the supply and return are connected to the same larger "one pipe"

    Screenshot 2024-11-06 at 5.42.55 PM.png

    Each section of baseboard radiator is connected to the next one on the line. Many times when the radiators are not physically next to each other, the pipe at one end drops below the floor then rises ul at the next radiator to continue the loop. Like this

    Screenshot 2024-11-06 at 5.51.32 PM.png

    There are other ways to pipe a radiator system also. Can you tell if you have the special Diverter tees or Monoflo® tee fittings anywhere or if you have a series loop? This can help determine the best way to fix your system

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    SuperTechpaul3x16
  • paul3x16
    paul3x16 Member Posts: 4
    https://forum.heatinghelp.com/discussion/comment/1818460#Comment_1818460

    Hydrotherm Boiler - Input 95,000 BTU/HR - output 76,000 BTU/HR

    image.png

    main loop 3/4" - 60' out and back

    branch piping 1/2" - average 20' out and back total of 12 radiators.

    the width of the house is 24' the pipes goes in the center, lenth of the house 52'

    this are the type of radiators that i have, i dont know how to get the EDR but i found the following

    6x 8sections - BTU @ 180°F: 3,056

    5x 16sections

    1x 36sections

    image.png

    https://forum.heatinghelp.com/discussion/comment/1818466#Comment_1818466

    i check the expantion tank its 12 PSI, and my system is also at 12 PSI.

    image.png

    my system looks like the one-pipe monoflo design that you suggested. i did not see those fittings that you showed me. instead i found the following. its not very clear. BTW i have two systems, its a 2 family house. i have to boilers, one boiler for the basement and 1st floor (12 radiators), and the other one for the 2floor (9).. thats why you see 2 pipes.. i believe this pipes are returning.

    image.png
    image.png
    image.png
    image.png

    its hard to tell since the house was build 1960, I'm going to try to take a better picture tomorrow.

    i think some of them look like this

    image.png

    Thank you for the help

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,212

    B4 you change the pump, you should remove the expansion tank from the system. You have to check and adjust the air pressure with the tank not having any water pressure on the tank. Then bleed the entire system and start the boiler.

    Monoflo system if that is what you have are difficult to bleed you may have to go back and forth and bleed the rads 2-3 times. 10' of pipe on a Monoflo system is a little long so that could be the reason and you may need a larger pump for that reason.

Categories