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.

Radiant Basics

J Meyer
J Meyer Member Posts: 4
I just finished reading Radiant basics written by John Siegenthaler. After reading this book, I still have some questions. I was hoping the wall could help. Here we go:

1. Is it standard to give each zone of PEX an extra 10 ft for hooking up with the manifold?

2. How do you check the moisture content of joists?

3. The equation for Coefficient of Performance is
CoP = Hc / (kw) 3413. Where does the 3413 come from?

4. How do I know what indoor and outdoor temperatures to use when finding the temperature differance?

Hopefully you can help me out. Thank you in advance.


  • Bill Nye
    Bill Nye Member Posts: 221

    1}You don't have to leave 10 ft., you could leave five or 20. The thing is, it would be better to waste 10 ft of tubing than be six inches short.

    2}They sell a meter at any good woodworking store that will measure moisture content of lumber. It has a probe that looks like a nail or pin that you stick into the wood.

    3}The 3415 is an eletrical thing. It is a unit of measure for the BTU's per KiloWatt Hour.

    4}You find what is called the design temperature for your area. The normal coldest day of the year. You can find it on the internet from NOA weather records. I know some one here on the wall has the link.

    The indoor temp. is how warm you want to keep your house. The typical outdoor is 0 to -10°F and the indoor is usually 70°F. So a 70 or 80 ° delta T, or difference in temperature.

    I hope I understood and answered your questions.
  • J Meyer
    J Meyer Member Posts: 4

    Thank you very much, you hit them right on the head.
This discussion has been closed.