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Comap Radiant Manifold Loop Balancing

Why is "Loop Balancing" important for Radiant Systems?

Water will flow in the path of least resistance, so when you start the circulator pump, water will flow through the loop (or loops) with the least  resistance.  Different tubing lengths, tubing wall friction and the number of bends in the tubing are some of the variables that determine  the amount of flow-resistance in each loop.  In extreme cases, with a large difference in loop flow-resistance, some loops may not have any flow at all.

Loop Balancing 

Comap Single Zone Radiant Manifolds with HRCMFLM Flow Meters

1)    Remove the black protective caps on the supply modules to expose the 5mm brass hex screw

2)    With a 5mm allen wrench, open all the supply module valves fully (rotate the 5mm brass hex screw counterclockwise), then replace all black protective caps.

3)    Adjust all radiant system thermostats to 90 F to start the circulator pump and/or open all of the zone valves.

4)    With the zone pump on, observe the flow rate indicators in all loops (the red disc inside the clear plastic tube on top of the flow meter module(s) is the flow rate indicator).    You'll need to adjust the flow if one or more of the loops are showing a higher flow rate than the other loops  To adjust flow, grasp the black base of the flow meter (the black base is what the clear plastic tube is mounted to) and rotate clockwise to close the flow valve or counterclockwise to open the flow valve.  To restrict flow in any loop indicating higher flow than the other loops, close the flow valve slowly until the flow rate in all loops is equal.

5)    If all flow meters indicate the same flow rate, your manifold is balanced and your system is ready for operation.

Comap Single Zone Radiant Manifolds with HRCMRM Return Modules (with no flow meters)

1)    Remove the black protective caps on the supply modules to expose the 5mm brass hex screw

2)    With a 5mm allen wrench, open all the supply module valves fully (rotate the 5mm brass hex screw counterclockwise), then replace all black protective caps.

3)    Remove the orange adjuster caps on all HRCMRM actuator return modules, then replace all caps slowly by turning clockwise until a slight resistance is felt (this is the point where the nub on the inside of the orange adjuster cap starts to engage the needle valve of the HRCMRM actuator modules). 

4)    Adjust all radiant system thermostats to 90 F to start the circulator pump and/or open all of the zone valves.

5)    Without flow meters, you'll need a digital contact thermometer for loop balancing. Same process as above except use return loop temperature instead of flow-rate to adjust (higher return loop temperature usually indicates a higher flow rate).  Using a rag to insulate your hand, press the tip of the digital contact thermometer probe to the return loop pex tubing, about 2" from the manifold.  Allow the temperature reading to stabilize, then record the temperature reading.  Repeat for all loops on the return manifold.  You'll need to adjust the flow rate if one or more of the loops are showing a higher temperature than the other loops  To adjust flow, turn the orange adjuster cap of the loop(s) with the higher flow 1/8 turn clockwise (closing the needle valve) and take new temperature readings.  Repeat this process until the temperature readings of all loops become equal. 

Updated 06/27/2010