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Wirsbo manifold adjustment

wrxz24wrxz24 Member Posts: 285
Just curious about the little back disc that controls the flow on the older cooper wirsbo manifolds 7 outlet with the black caps.  I saw a post on the Main Wall about someone who said to adjust all of the black disc so that it is about a dimes thickness above the brass collar.  Mine discs were level or slightly below and there was about a 14 degree temperature differential (90 vs 76 )between each of  supply and return loops.  Temperature was 4 degrees. 

My question is this.  Is there a recommended temp difference between the supply and return loops after the system has been up and running?

Thanks in advance.


  • Mark EathertonMark Eatherton Member Posts: 5,584

    I am the guilty party :-)

    The dime setting will keep the plunger mid way between completely closed and completely open. A starting point for up or down adjustments if you will.

    The system or floor delta T at less than design conditions is going to be all over the place, depending upon many variable, most of which we have little to no control over.

    What is more important is that they all realize approximately the same temperature drop. If you've got some that are low DT's, then close them off to exert more flow into the circuits with the higher DT's.

    There could also be some air binding issues at hand, causing flow imbalances, and resultant large temperature differentials.

    Although we design hot water baseboards for 20 degree DT at design condition, I have only seen it once. All others, even at design conditions were in the 7 to 12 degree DT.

    Per the RFH manufacturers, they'd rather see a small DT on their floors, because it equates to a higher average surface temperature which is good for delivering comfort. Not unusual to see them going for a 10 degree DT. If a designer wanted to go for a larger DT, they could, but it is going to create hot and cold spots. If they incorporate a 4 way reversing valve, that will eliminate hot/cold spots, and keep the flow rates down, and the DT high (relatively speaking). The Germans use a 30 degree DT in their designs (Celcius, not Fahrenheit), but they do things differently over there than we do here. Including using the comment, "If you are cold, put on a sweater..." I think it is referred to as Euro-Cave comfort conditions. Not acceptable in the North AMerica market place.

    When dealing with low mass staple up systems, the DT is typically even smaller yet due to the lack of heat transfer. Too many things working against you.

    Remember, Delta T is a design principle, with very little co-relation to reality. Design does NOT take into consideration all of the real time things that go on in our world, like internal gains, flow rate variables, internal gains, placed R values over the heat emitter etc. If you're not uncomfortable, then don't worry about it. If it ain't broke, don't fix it for the sake of providing a lower entering water temperature into your mudcon appliance. If you are uncomfortable in certain areas, it may not necessarily be an imbalance in flows, but could also be poor thermostat placement, or poor zoning layout.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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