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Armstrong monoflo Tee's & infloor loop

benrk Member Posts: 4

I have an older home with a one line radiant system, which I'm completely unfamiliar with & the kitchen add on was unheated. Since all wall space in the kitchen is taken up by cabinetry, in floor heat was a logical conclusion, the loop is in place now & earlier this year when I replaced the circulator pump & had the system drained I wanted to replace the plugs in an unused pair of Armstrong Tee's with ball valves in anticipation of the kitchen loop.

The plug on the return Tee came out easy, the square on the supply tee's plug disintegrated, so - being unaware of the exact system properties - I just set a valve on another unused supply tee further down the main loop, so now that the kitchen loop is installed & hooked up, guess what, it filled, but has no flow.

So my questions: what do these Armstrong Tees exactly look like inside, do both return & supply have a venturi nozzle just in opposite orientation?

By my understanding, both supply & return produce resistance in the main loop, shouldn't I still have a flow, only in opposite direction from what I intended? Is hooking up the return line to the return tee 1' downstream of the used supply tee going to change anything?

My kitchen loop is about 200' 1/2" o2pex with 2 cuts/couplings & 30 u-turns & sits about 1' above the main loop, does my loop produce too much resistance?

The used set of tees is near the end of the main loop, there is another unused set near the beginning of the main, can I hook up the supply to the beginning of the main & return to the end to have a greater pressure difference (needbe partially closing ball valves on kitchen loop to maintain flow in the main)?

Thx for your help, Ben


  • Paul S_3
    Paul S_3 Member Posts: 1,257
    edited December 2012

    first if you remove a radiator from those diverter tee's you must not plug them, it will slow water flow either take the diverter tee's out or run a piece of copper tubing between each tee so water can flow freely, and as for using those tee's to run a loop for radiant heat it will not work .....run it off the boiler as a separate zone...and yes your loop does have too much resistance it's easier for water to flow between the two diverter tee's than flow through 200' of pex tubing...
    ASM Mechanical Company
    Located in Staten Island NY
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  • benrk
    benrk Member Posts: 4

    So, I guess I got lucky with this one, 1st I moved the return to the the return-T corresponding with the supply-T used, this is the last pair of T's in the main loop, still no flow, next I moved the supply-line to the other unused supply-T, which is 1st in the main loop, so parallel to my floor loop I have the entire system with all radiators producing resistance in the main loop & it works, I have a pretty good flow! Supply & return have a notable temperature difference, but return is still very warm & the main loop & radiators also get as hot as normal, I guess with one less pair of T's plugged, I actually improved overall system performance & the kitchen is warm & there's no more frozen water lines, yea, I like that & she does too :-)
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