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Too many feet of baseboard?

This continues from a few days ago. New construction of a three family building. Each floor has about 56 feet of baseboard connected in what appears to a be a single loop. Is this excessive for 1/2 inch plastic distribution pipe? Will the temp drop be too great for enough heat in the rooms furthest from the supply end?


  • Steamhead
    Steamhead Member Posts: 14,832
    Sure is

    the limit for 3/4" supply pipe is just over 60 feet of baseboard.

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    EBEBRATT-Ed Member Posts: 10,235

    1/2" is good for abt. 1.5 gpm or 15,000 btu about 25-30 feet depending on your baseboard rating and water temperature
  • Ted Robinson
    Ted Robinson Member Posts: 126

    Thanks for the help & information.
  • Joe Mattiello
    Joe Mattiello Member Posts: 621
    When is 56 feet of baseboard too much?

    When using 1/2" pipe if the total length of pipe is too much. I'm assuming the baseboard is 3/4" pipe, and the supply piping is 1/2", so we need to know how many lineal feet of pipe to calculate the pressure drop. If the head and velocity are acceptable then you can size the pump. Maximum flow through 1/2" pipe is approximately 3 gpm which is close to 3.4 gpm required to satisfy the load. But what about the system curve? Can the pump deliver it without exceeding the 4 ft per second velocity? You can still make it work regardless, but the flow might not be 100%.
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    EBEBRATT-Ed Member Posts: 10,235

    Sorry but I don't agree. 1/2 " is good for about 1.5 gpm. 3/4 is good for about 4. Most people in the industry size for a resistance of 4'/100 feet of pipe. Based on a 20 degree TD which is standard 1/2"=15,000 btu/hr and 3/4 is 40,000 btu/hr. Select the pipe size based on the btu requirement you need and then devide the btu requirement by the rating of btu/ foot that your baseboard requires. Most residential baseboard is in the range of 400-700 btu/foot depending on your average water temperature.

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