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.

Where to begin....

Need some very basic help and recommendations for reading material.

Currently, I have a 1896 farmhouse - with a 1920s addition.  The 1896 part of the house is heated with a gravity fed boiler system.  Boiler was replaced at some point and is now a Teledyne JVT-125 125,000 BTU boiler.  There also is a circulating pump that was added.

There are 1" cooper lines that come out of the boiler and tie into the old larger 3" piping to the radiators.

In the future I plan to add a wood gasification boiler and a thermal-solar array with hot water storage in an old cistern in the basement.  I will still keep the LP fired boiler as a emergency backup.

The current question is - can I replace the large piping with PEX and a manifold system.  Right now the old piping takes up a fair amount of space that I want to use for wood storage.

I was thinking of replacing it all with 1" to match the size coming out of the boiler.  When I do the upgrades I plan on adding radiators to the 1920s side as there aren't any there now.



  • Ironman
    Ironman Member Posts: 6,868
    A Place to Begin

    Here's an article of Dan's from the "Systems" tab above:


    You'll need to do a heat loss calculation before any accurate pipe and circulator sizing can be done.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • thesmackdown
    thesmackdown Member Posts: 3
    Pipe sizing

    It's already been converted to a circulating system.

    The question is can I just match the pipe side and install a distribution manifold.

    A heat loss calculation would be a waste of time right now as I am planning on getting the whole house insulated in the spring or summer.
  • Gordy
    Gordy Member Posts: 9,514
    edited December 2011
    Planned envelope upgrades, and heat loss

     Heat loss is easy just use your planned upgrades for the data inputs in the heat loss program. With out it working over the system is a stab in the dark.

     The heat loss will dictate the flow rates, the pipe sizes needed to deliver the flow rates, emitter size, and water temps needed to heat each room.

     Your converted gravity system is probably going to be way over sized after insulation upgrades. This is not all bad since it will allow you to use lower supply temps to the emitter saving energy. Unless of course someone has done some changes before you aquired the property.

     Do some reading from Dans wonderful library. Start off with hot water heating, and gravity systems as been pointed out in the link. Understanding how they were built, and designed back then will help you achieve a more modern system done correctly.

     Hydronics is a science. You can not just go through, and change pipe sizes, and add elbows etc. You may end up with a mess.

     Everyone is here to help. Just ask the questions.


  • thesmackdown
    thesmackdown Member Posts: 3
    Heat loss

    After doing a heat loss calculation after the planned upgrades, I came up with 98,000 BTUs.

    So, where do I go to learn about pipe sizing?
  • Gordy
    Gordy Member Posts: 9,514
    edited January 2012
    Dan has

     Some very good books that are not pricey. Pumping away, Hydronic radiant heating, Primary secondary made easy, How Come?, Classic Hydronics.

     1 1/2" Copper will carry 220,000 btus at 22 GPM.

    1 1/4"  Copper will carry 140,000 btus at 14 GPM.

    1"       Copper will carry 80,000 btus at 8 GPM.

    3/4"    Copper will carry 40,000  btus at 4 GPM.

    1/2"    Copper will carry 15,000 btus at 1.5  GPM.

    3/8"    Copper will carry   7,500 btus at .75 GPM

    Type L copper pipe with 20* DT.  IF you go with 10* DT divide Btus by 2.
  • JohnHenry_2
    JohnHenry_2 Member Posts: 70
    To answer your original question;

    Yes, you can replace the original iron piping with pex home runs to a manifold system.

    It'll take a not insignificant amount of time and dough, but you'll end up with a more responsive, controllable and possibly economical system.
    The bitterness of poor quality remains long after the sweetness of low price is forgotten.
This discussion has been closed.