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9. Do not locate any point in the drain system above the
drain connection of any unit.
10. Automatic flow controlled devices must not be
installed prior to system cleaning and flushing.
11. A high point of the piping system must be vented.
12. Check local code for the need for dielectric fittings.
Figure 8. Typical Vertical Unit Piping
Ball Valve with
Y-Strainer
Isolator Pad
Flexible Return Hose with
Swivel Fittings
Condensate
Drain
Supply Air
Flexible Duct Collar
Two 90° Turns
(Ductwork Sized
Based on Airflow)
Acoustical Thermal
Duct Lining (10’)
Cleaning & Flushing System
1. Prior to first operation of any conditioner, the water cir-
culating system must be cleaned and flushed of all con-
struction dirt and debris.
If the conditioners are equipped with water shutoff
valves, either electric or pressure operated, the supply
and return runouts must be connected together at each
conditioner location. This will prevent the introduction of
dirt into the unit. See Figure 9.
Figure 9.
2. Fill the system at the city water makeup connection with
all air vents open. After filling, close all air vents.
The contractor should start main circulator with the
pressure reducing valve open. Check vents in sequence
to bleed off any trapped air, ensuring circulation through
all components of the system.
Power to the heat rejector unit should be off, and the
supplementary heat control set at 80°F (27°C).
While circulating water, the contractor should check
and repair any leaks in the piping. Drains at the lowest
point(s) in the system should be opened for initial flush
and blow-down, making sure city water fill 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 contin-
ue for at least two hours, or longer if required, to see
clear, 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 runouts should
now be connected to the conditioner supply and return
connections. Do not use sealers at the swivel flare con-
nections of hoses.
4. Trisodium phosphate was formerly recommended as a
cleaning agent during flushing. However, many states
and localities ban the introduction of phosphates into
their sewage systems. The current recommendation is to
simply flush longer with warm 80°F (27°C) water.
Return Runout
Supply Runout
Mains
Flexible Hose
Runouts Initially
Connected Together
Note: Do not over-torque fittings. The maximum torque without damage to
fittings is 30 foot pounds. If a torque wrench is not available, use as a rule
of thumb, finger-tight plus one quarter turn.
Return Air
Flexible Supply Hose with
Swivel Fittings
Ball Valve
with Mesurflo
®
Line Voltage Disconnect
Blower Motor Access
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