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Hot water boiler

johnjohn89
johnjohn89 Member Posts: 100

Boiler experts Question please! 

For two story house , boiler in the basement , 8’ for basement, 1st floor about 9’, baseboard radiation about 1’ total 18ft 

1’ is for baseboard radiation length or tall? What about if u have multiple baseboard radiation on first floor. Do u need to add 1 ft for each baseboard radiation?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 22,934
    Say what? One foot of what added to what?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    mattmia2johnjohn89
  • Intplm.
    Intplm. Member Posts: 1,801
    Are you asking how much heat or radiators you need?
  • ratio
    ratio Member Posts: 3,605
    @johnjohn89, you're a little incoherent here. Are you asking about boiler fill pressure in feet of head?
  • johnjohn89
    johnjohn89 Member Posts: 100
    Say what? One foot of what added to what?
    If basement about 8’ and 1st floor about9 , baseboard radiator on 1st floor, what will be my expansion tank set for 20psi? 8+9 and plus 3 ft for ceiling ? Do I need  add tall of radiator  1ft? If yes why , if no and why? Thanks
  • johnjohn89
    johnjohn89 Member Posts: 100
    ratio said:
    @johnjohn89, you're a little incoherent here. Are you asking about boiler fill pressure in feet of head?
    If basement about 8’ and 1st floor about9 , baseboard radiator on 1st floor, what will be my expansion tank set for 20psi? 8+9 and plus 3 ft for ceiling ? Do I need  add tall of radiator  1ft? If yes why , if no and why? Thanks
  • johnjohn89
    johnjohn89 Member Posts: 100
    Intplm. said:
    Are you asking how much heat or radiators you need?
    If basement about 8’ and 1st floor about9 , baseboard radiator on 1st floor, what will be my expansion tank set for 20psi? 8+9 and plus 3 ft for ceiling ? Do I need  add tall of radiator  1ft? If yes why , if no and why? Thanks
  • pecmsg
    pecmsg Member Posts: 4,696
    1 story 8#’s
    2 stories 12#’s
    mattmia2
  • mattmia2
    mattmia2 Member Posts: 9,459
    It is based on the distance from the top of the boiler to the highest piping in the system. It is about 2.3 ft for every psi of pressure plus about 4 psi for things like the differential caused by the resistance in the piping and the flow produced by the ciruclator so the standard 12 psig charge and prv setting is good for the highest piping being about 18 ft above the boiler.
  • jesmed1
    jesmed1 Member Posts: 554
    edited December 2023

    Do I need  add tall of radiator  1ft? If yes why , if no and why? Thanks

    Yes, you need to add the height of the radiator. You want to calculate the height of the highest place water will flow to, which is the top of your highest radiator. So that's the distance from your boiler in the basement to the basement ceiling (8 feet) plus the height of the first floor (9 feet), plus the height of the tallest radiator on the second floor. If you had cast iron radiators, they might be 3 feet tall. But you have baseboard radiators at 1 foot tall, so adding 1 foot height gives you 8+9+1=18 feet total.

    Then 18 feet x .43 psi per foot = 8 psi. Then you want to add 5 psi so that you maintain 5 psi at the highest point of the system, so 8 + 5 = 13 psi for your example. That's the minimum pressure you want to maintain.

    (You said something about adding a 3 foot ceiling. I think you mean the two floor/ceiling thicknesses added 3 feet total to your height calculation. So if we add 3 feet for the floor/ceiling thicknesses, that's 21 feet, which gives you 14 psi minimum with the 5 psi margin.)

    If your expansion tank is already set for 20 psi, you can run your system at 20 psi. You just don't want to go lower than 13-14 psi.

  • johnjohn89
    johnjohn89 Member Posts: 100
    jesmed1 said:
    Do I need  add tall of radiator  1ft? If yes why , if no and why? Thanks
    Yes, you need to add the height of the radiator. You want to calculate the height of the highest place water will flow to, which is the top of your highest radiator. So that's the distance from your boiler in the basement to the basement ceiling (8 feet) plus the height of the first floor (9 feet), plus the height of the tallest radiator on the second floor. If you had cast iron radiators, they might be 3 feet tall. But you have baseboard radiators at 1 foot tall, so adding 1 foot height gives you 8+9+1=18 feet total. Then 18 feet x .43 psi per foot = 8 psi. Then you want to add 5 psi so that you maintain 5 psi at the highest point of the system, so 8 + 5 = 13 psi for your example. That's the minimum pressure you want to maintain. (You said something about adding a 3 foot ceiling. I think you mean the two floor/ceiling thicknesses added 3 feet total to your height calculation. So if we add 3 feet for the floor/ceiling thicknesses, that's 21 feet, which gives you 14 psi minimum with the 5 psi margin.) If your expansion tank is already set for 20 psi, you can run your system at 20 psi. You just don't want to go lower than 13-14 psi.
    ☺️ thank u so much, finally this is answer I want🙏👍.
    jesmed1MikeAmann