WaterFurnace CLW Chiller - Manual (Page 10)

10
CLW QUAD SERIES CHILLER INSTALLATION MANUAL
System Cleaning and Flushing
Cleaning and Flushing
Prior to start up of any heat pump, the water circulating
system must be cleaned and flushed of all dirt and debris.
If the system is equipped with water shutoff valves, the
supply and return runouts must be connected together
at each unit location (This will prevent the introduction of
dirt into the unit, see Flushing with Water Shutoff Valve
Equipped Systems illustration). The system should be filled
at the water make-up connection with all air vents open.
After filling, vents should be closed.
The contractor should start the main circulator with the
pressure reducing valve makeup open. Vents should be
checked in sequence to bleed off any trapped air and to
verify circulation through all components of the system.
As water circulates through the system, the contractor
should check and repair any leaks found in the piping
system. Drain(s) at the lowest point(s) in the system should
be opened for initial flush and blowdown, making sure
water fill valves are set at the same rate. Check the pressure
gauge at the pump suction and manually adjust the make-
up water valve to hold the same positive pressure both
before and after opening the drain valves. Flushing should
continue for at least two hours, or longer if required, until
drain water is clean and clear.
The supplemental heater and/or circulator pump, if used,
should be shut off. All drains and vents should be opened
to completely drain the system. Short-circuited supply and
return runouts should now be connected to the unit supply
and return connections.
Refill the system with clean water. Test the system water
for acidity and treat as required to leave the water slightly
alkaline (pH 7.5 to 8.5). The specified percentage of
antifreeze may also be added at this time. Use commercial
grade antifreeze designed for HVAC systems only.
Environol™ brand antifreeze is recommended.
Once the system has been filled with clean water and
antifreeze (if used), precautions should be taken to protect
the system from dirty water conditions. Dirty water will
result in system-wide degradation of performance, and
solids may clog valves, strainers, flow regulators, etc.
Additionally, the heat exchanger may become clogged
which reduces compressor service life and can cause
premature unit failure.
In boiler/tower application, set the loop control panel
set points to desired temperatures. Supply power to all
motors and start the circulating pumps. After full flow has
been established through all components including the
heat rejector (regardless of season), air vented and loop
temperatures stabilized, each of the units will be ready for
check, test and start up and for air and water balancing.
Ground Source Loop System Checkout
Once piping is completed between the unit pumping
system and ground loop, final purging and charging of
the loop is needed. A high pressure pump is needed to
achieve adequate flow velocity in the loop to purge air
and dirt particles from the loop itself. Antifreeze solution
is used in most areas to prevent freezing. Flush the
system adequately to remove as much air as possible;
then pressurize the loop to a static pressure of 40-50
PSI (summer) or 50-75 PSI (winter). This is normally
adequate for good system operation. Loop static pressure
may decrease soon after initial installation, due to pipe
expansion and loop temperature change. Running the
unit for at least 30 minutes after the system has been
completely purged of air will allow for the “break-in”
period. It may be necessary to adjust static loop pressure
(by adding water) after the unit has run for the first time.
Loop static pressure will also fluctuate with the seasons.
Pressures will be higher in the winter months than during
the cooling season. This fluctuation is normal and should be
considered when charging the system initially.
Ensure the pump provides adequate flow through the unit
by checking pressure drop across the heat exchanger.
Usually 2.25-3.0 GPM of flow per ton of cooling capacity is
recommended in earth loop applications.
Return Runout
Supply Runout
Mains
Rubber Hose
Runouts Initially
Connected Together
Flushing with Water Shutoff Valve Equipped Systems