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Installation, Operation & Maintenance - HKV Series
Note: Comfort-Aire/Century strongly recommends
all piping connections, both internal and external
to the unit, be pressure tested for leakage by an
appropriate method prior to any finishing of the
interior space or before access to all connections
is limited. Comfort-Aire/Century will not be
responsible or liable for damages from water leaks
due to inadequate or a lack of pressurized leak
testing during installation.
Cleaning and flushing of the WLHP piping system is the
single most important step to ensure proper start-up
and continued efficient operation of the system.
Follow the instructions below to properly clean and flush
the system:
1. Verify electrical power to the unit is disconnected.
2. Install the system with the supply hose connected
directly to the return riser valve. Use a single length of
flexible hose.
3. Open all air vents. Fill the system with the water. DO
NOT allow system to overflow. Bleed all air from the
system. Pressurize and check the system for leaks and
repair appropriately.
4. Verify all strainers are in place. (Comfort-Aire/Century
recommends a strainer with a #20 stainless steel wire
mesh.) Start the pumps, and systematically check each
vent to ensure all air is bled from the system.
5. Verify make-up water is available. Adjust make-up
water appropriately to replace the air which was bled
from the system. Check and adjust the water/air level
in the expansion tank.
6. Set the boiler to raise the loop temperature to ap-
proximately 85°F [29°C]. Open the a drain at the
lowest point in the system. Adjust the make-up water
Piping System Cleaning & Flushing
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CAUTION!
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CAUTION!
To avoid possible damage to a plastic (PVC)
piping system, do not allow temperatures to exceed 110°F
[43°C].
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CAUTION!
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CAUTION!
DO NOT use 'stop leak' or any similar chemical
agent in this system. Addition of these chemicals to the loop
water will foul the system and inhibit unit operation.
replacement rate to equal the rate of bleed.
7. Refill the system and add trisodium phosphate in a
proportion of approximately one pound per 150 gal-
lons [1/2 kg per 750 L] of water (or other equivalent
approved cleaning agent). Reset the boiler to raise
the loop temperature to about 100°F [38°C]. Circulate
the solution for a minimum of 8 to 24 hours. At the
end of this period, shut off the circulating pump and
drain the solution. Repeat system cleaning if desired.
8. When the cleaning process is complete, remove the
short-circuited hoses. Reconnect the hoses to the
proper supply, and return the connections to each of
the units. Refill the system and bleed off all air.
9. Test the system pH with litmus paper. The system
water should be slightly alkaline (pH 7.5-8.5). Add
chemicals, as appropriate, to maintain acidity levels.
10. When the system is successfully cleaned, flushed,
refilled and bled, check the main system panels, safety
cutouts and alarms. Set the controls to properly main-
tain loop temperatures.