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Radiant heat and monoflo tees?

Steve_75 Member Posts: 20
I am an ex heating guy who is installing radiant heat for the first time. As I have read about "long manifolds" they seem to be just one pipe systems and whenever I used to do these I would use monoflo tees to get the water to go where I needed it. I find no mention of these in radiant heat where the loops are up to 300 feet long. Why is that??? It seems it would be a much more efficent way to get the water down each loop - what am I missing?


  • Monoflo & first timer radiant floor warmer

    Not quite sure what your question is. Please be more specific. I'm not familiar with the term of "long manifold". Do you mean remote manifold?

    I've used a simple set of tees> (one monoflow) off of existing hi-temp loops (blow & go design) and basically clipped/suspended the tubing using a staple gun that holds off the tubing from the surface under the floor with great results through heavily dense subfloors in various floor coverings. No design just gut feeling and heavy doses of gumption along with my regular meds;-).

    I think what you may be missing is the science of efficient piping practace. A 300' monoflow loop may not be well served in the context of efficiency. The efficient system will be a by-product of a smart design. 40ºdelta-T only goes so far on a warm floor/radiator.

    Try the RPA's website for more on RFH. www.radiantpanelassociation.org

    Hope this helps.

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  • Steve_75
    Steve_75 Member Posts: 20

    I was probably not descriptive enough - I have a total of 11 zones each with its own Taco 007 or 008. I am running 2-300' loops (or 6 - 100' loops) in one of the zones.

    In this one zone I am running 3/4 " copper as a "manifold" the 3/4 goes down 40' and returns the same 40'. I then have the loops of 1/2" PEX tubbing as the branch. This looks the same as an old two pipe system where the feed is off one of the 3/4 and the return going into the other.

    My question is - can you use Monoflo tee(s) and make it a one pipe system? Feed and return on the same 3/4 pipe with a Monoflo tee on the return. Yes I know this doesn't save any piping as I still need to return to the originating point but it seems to me that the Monoflos may force water down these branchs better then the two pipe feed and return system. Your thoughts?
  • S Davis
    S Davis Member Posts: 491

    Why not just use regular radiant manifolds?
    This way you would have flow adjustment on each loop and you could use telestats and have one system pump instead of eleven cutting your electrical usage from about 8.5 amps to about 1.5 amps this would also simplify your controls.

    S Davis

    Apex Radiant Heating
  • Steve_75
    Steve_75 Member Posts: 20

    Maybe I just don't understand as I am new to radiant heat but here is my logic - these rooms are up to 40 feet away from the heat source so rather then bring every loop back to home it is easier, and a lot less pipe, to use a feed and return pipe. If I bring all loops back I will have around 20 pipes to put into maifolds. Remote manifolds are not an option as the piping will be closed in and not accessable. I do have a manifold back at the heat source wjere each of the zones tie in. As for using circulators - probably left over from my days of doing service work and all of the headaches with zone valves as well as worrying about the load on one pump. Doing a pump per zone at the source makes it easier to me to balance- probably shows how out of touch I am with radiant heat.
  • sebast
    sebast Member Posts: 30

    Steve, long manifold is great but you have to use a reverse return meathod. The piping that you explained 40' down and 40' back, pipe the return in a reverse. I have attached a doc. on this, put your loops in place of the loads from this attachment. I have never seen mono-flos used, would it work?? Don`t know
  • Steve_75
    Steve_75 Member Posts: 20

    Thanks, this is helpful. It shows a typical two pipe system and is probably a lot safer to stay with using the first in last out. I used monoflo in the past as it worked well for radiators and allowed for a very even heat that was easy to balance at each radiator. They work great if the resistance through the radiator isn't too much and radiators are pretty much wide open. It just seemed that using a monoflo tee to push water through a 300' loop may be more of a pressure drop then it could handle. - now to go pipe those loops!
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