Cleaning & Flushing System - McQuay MWSC 010 Series Manual

Cleaning & Flushing System
1. Prior to fi rst operation of any conditioner, the water circulating system must be cleaned and fl ushed of all
construction dirt and debris.
If the conditioners are equipped with water shut off valves, either electric or pressure operated, the supply and
return run outs must be connected together at each conditioner location. This will prevent the introduction of dirt
going into the unit.
2. Fill up the system at the city water makeup connection with all air vents open. After fi lling, close all air vents. The
contractor should start with main circulator by open the pressure reducing valve. Check vents in sequence to
bleed off any trapped air, ensuring circulation through all components of the system.
Power off the heat rejecter unit, and set the supplementary heat control at 27°C. While circulating water, the
contractor should check and repair any leakage along the piping. Drain at the lowest point(s) in the system
should be opened for initial fl ush and blow down, making sure city water fi ll valves are set to make up water at
the same rate. Check the pressure gauge at pump suction and manually adjust the makeup to hold the same
positive steady pressure both before and after opening the drain valves. Flush should continue for at least two
hours, or longer if required, to see clear and clean drain water.
3. Shut off supplemental heater and circulator pump and open all drains and vents to completely drain down the
system. Short circuited supply and return run outs should now be connected to the conditioner supply and return
connections. Do not use sealers at the swivel fl are connections of hoses.
4. Trisodium phosphate was formerly recommended as a cleaning agent during fl ushing. However, many states
and localities ban the introduction of phosphates into their sewage systems. The current recommendation is to
simply fl ush longer with 27°C warm water.
5. Refi ll the system with clean water. Test the water using litmus paper for acidity, and treat it as required to leave
the water slightly alkaline (PH 7.5 to 8.5). the specifi ed percentage of antifreeze may also be added at this time.
Use commercial grade antifreeze designed for HVAC systems only. Do not use automotive grade antifreeze.
Once the system has been fi lled with clean water and antifreeze (if used), precautions should be taken
to protect the system from dirty water conditions. Dirty water will cause the in system wide degradation of
performance and solids may clog the valves, strainers, fl ow regulators, etc. Additionally, the heat exchanger may
be clogged which reduces compressor service life or causes premature failure. A System Saver® from McQuay
International should be employed to continuously remove solids as the system operates. Contact your local
representative for further information on this device.
6. Set the loop water controller heat add set point to 21°C and the heat rejection set point to 29°C and turn on all
motors and start the circulating pumps. After full fl ow has been established through all components including the
heat rejecter (regardless of season) and air vented and loop temperatures stabilized, each of the conditioners
will be ready for check, test and start-up, air balancing, and water balancing.
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