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What is the BTU rating on pipe sizes?

Brad
I am told that if you tie an indirect htr into a boiler system the coil can only hanle what it is sized for. I am not sure how they size the coil. I thought it went by pipe size?
Thanks
John

Comments

  • John Reynolds
    John Reynolds Member Posts: 22
    BTU ratings on pipe size

    I am trying to figure out if a tank needs to have an ASME rating. Inspector says if I am under 120 gallons and below 199K btu. Im good. I need to know btu rating on pipe taping to tank. I cant restrict them must know ratings and cant find any tables.

    Thanks
    John
  • Brad White_203
    Brad White_203 Member Posts: 506
    Not sure I follow...

    the question. A tank by itself is an "unfired pressure vessel" according to ASME (VIII). The volume is yours to figure out and the BTU capacity is related to the system to which it is connected. (The tank itself, being unfired is dependent on an interconnected external heat source, also under your control, one presumes).

    If there is an immersion heater and the duty exceeds that BTU rating, then that would settle the matter one way or the other.
  • Brad White_203
    Brad White_203 Member Posts: 506
    Surface area

    A given pipe size can handle a wide variety of BTU requirements. Depending on the delta-T, I can move between one and a million BTU's (seriously), through a given pipe and enough pressure to go along with that.

    I do not mean to dodge the question, but any association between pipe size and BTU capacity is at best based on guidelines for a certain Delta-T. Could be 2-3 times that, even much more in normal practice.


    If the heater is ASME it should have a stamp, nameplate and rating on it.
  • scrook_2
    scrook_2 Member Posts: 610
    Flowrate & deltaT?

    Coil inside diameter will limit max flowrate, temperature, and the differance between boiler water & domestic water temperatures will limit max temperature differential at a given flowrate.

    What's coil's max flow rating?

    How big are the tappings?

    What's your *actual* flow (based on the coil plus connecting plumbing resistance and performance curve of the circulator used)?

    What's your estimated delta Temp across the coil?

    If you know actual flowrate and delta T (and fluid used, water+antifreeze will carry less slightly BTU's than plain water) than you can calculate BTU's delivered, e.g. 15 GPM water at 10° delta T will deliver ~75,000 BTU/hr; double *either* the delta T *or* the flowrate and you can deliver ~150,000 BTU/hr... etc.
  • John Reynolds
    John Reynolds Member Posts: 22
    btu

    Brad
    Sorry if im not clear. I know about the stamp.
  • John Reynolds
    John Reynolds Member Posts: 22
    btu

    Brad
    Sorry if im not clear. I know about the stamp.I was asked to replace a triangle tube tr-80 with an updated Smart 80. I know these are not asme rated. The local inspector told me if the tappings cannot exceed 200k btu I would be fine. I thought there was a simple chart somewhere. It is a 300K boiler with water at 20Psi and a taco 0010 circ. the tapping would be 1 1/2" i think a delta T of 20'
    Thanks
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,314


    "SMART water heaters are exempt from ASME
    Section VIII, Division 1 Code construction per
    Interpretation VIII-86-136. Check with local codes
    for applicability" This is Triangles tube's view on ASME. Yes I did cut and paste it from their manual. Also they list 300k btu for this tank What if you use 2 smart 40's? They are under. May also be able to stage them for lower cost abd faster recovery? of course you do not have room I am guessing.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
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