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.

split loop

Brad White
Brad White Member Posts: 2,398
as a general statement, I would say that yes, splitting the loop will yield better distribution, assuming it is all on the same zone (thermostat), or if split into separate zones it is going to follow how you live in the space or by solar exposure.

Assuming you are splitting it nearly in two and this is all on the same thermostat, you would be cutting your total flow in half and your piping pressure drop by nearly 75%. In other words, you would have plenty of water flow to play with. This will allow you to balance each side to what it really needs.

Any cold spots will fare better. You cut the chance of a "cold end" right about in half.

Not that you asked, but here of the many paradoxes in heating is the notion of evenness and average water temperature:

If you have a single-tier of fin tube and you feed it in one direction, the water temperature degrades in direction of flow. The last element will see cooler water than the first. It has to. The "average" water temperature would be right about in the middle of the run. Upstream would be hotter, downstream would be colder.

Take the same series of rooms but use two-tier element with the return loop below the supply. A "U" configuration laying on it's side. The average water temperature now is approximately at the end of the first pass, the u-bend at the end.

But you know what? With the u-configuration, no matter where you draw a vertical line through the element, each point has the same average water temperature. The entering water and leaving water for the circuit represent the average as does any other point along the way.

No reason to mention that. I just thought it was neat and might get you thinking of other things to do. :)
"If you do not know the answer, say, "I do not know the answer", and you will be correct!"

-Ernie White, my Dad


  • Jorge
    Jorge Member Posts: 26
    To split or not to split ?

    Rule of thumb how long can a 3/4" hwbb loop be before it needs to be split. Element and piping to and from boiler.I have a loop on my first floor split level house that is about 275ft when you add in the elbows .Is this to large of a loop? I have 58ft of 3/4" element. I wanted to split the loop 28ft of element on one side and 30ft on the other. Would the system be balanced better if it were split?
  • Timco
    Timco Member Posts: 3,040

    Do all the BB heaters heat up evenly, or do the last ones stay cooler? That may be the question, as well as what is pushing them? (circ size?) If you split it up, that's the time to make zones for better control of the overall comfort.

    Just a guy running some pipes.
  • Jorge
    Jorge Member Posts: 26

    The last one in the family room is a bit cooler then the rest as it is on the end of the loop. I have a bg nrf22 pumping now. I was going to put a Grundfos usp1558fc 3 speed to give me better control if I need to split the loop.
This discussion has been closed.