JOHNSON CONTROLS
80
FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
SECTION 2 – INSTALLATION
c. If the water regulating valve is placed in se-
ries with the condenser, it should be installed
in the water line leaving the condenser and
should shut down to prevent water from si-
phoning out of the condensers.
d. For systems where a constant pumping head
is required, the water regulating valve may
be installed in a bypass line around the con-
densers. It must be open on falling discharge
pressure. These typical systems, depending
on the specific application, must maintain
a constant condensing pressure regardless
of temperature conditions and must provide
adequate head pressure for proper thermal
expansion valve operation.
Condenser tube water velocities must not
exceed 10 feet per second to prevent ero-
sion of the pipe.
After condenser water has been supplied
to the system and prior to unit operation
any trapped air must be removed from
the condensers. To do this remove the 3/8
inch pipe plug from top of the head of the
condenser on the end opposite the piping
connection (control box side of the unit)
and leave it open until water starts to come
out the connection. Reinsert the plug. This
sequence must be performed on each of
the condensers.
Cooling Towers
Cooling tower control affects the unit cycle rates. Con-
denser water temperature swings from 10.0–15.0°F
may cause excessive compressor, water valve and unit
cycling. Be sure to set the tower controls to minimize
compressor unit cycling.
Water Quality
An LSW water-cooled self-contained unit may be suc-
cessfully applied in a select range of commercial and
industrial applications. It is the responsibility of the
system designer and installing contractor to ensure that
acceptable water quality is present and that all appli-
cable codes have been met in these installations.
Water Treatment:
Do not use untreated or improperly
treated water. Equipment damage may occur. The use
of improperly treated or untreated water in this equip-
ment may result in scaling, erosion, corrosion, algae or
slime. The services of a qualified water treatment spe-
cialist should be engaged to determine what treatment,
if any, is required. The product warranty specifically
excludes liability for corrosion, erosion or deteriora-
tion of equipment. The heat exchangers in the units are
tube and shell construction consisting of steel and cop-
per. The water piping to the heat exchanger is copper.
There may be other materials in the building’s piping
system that the designer may need to take into con-
sideration when deciding the parameters of the water
quality. If an antifreeze or water treatment solution is to
be used, the designer should confirm it does not have a
detrimental effect on the materials in the system.
Contaminated Water:
In applications where the wa-
ter quality cannot be held to prescribed limits, the use
of a secondary or intermediate heat exchanger is rec-
ommended to separate the unit from the contaminated
water. Failure to supply a secondary heat exchanger
where needed results in a warranty exclusion for pri-
mary heat exchanger corrosion or failure.
Waterside Piping Arrangements
Install a condenser water pump between the cooling
tower (either open or closed) and the self-contained
unit. Lay out the remainder of the system’s condenser
piping in reverse returns. This helps balance the system
by equalizing the length of supply and return pipes.
Multistory buildings may use a direct return system
with balancing valves at each floor.
Install the supply riser and its return in close proximity.
Furnish both with permanent thermometers to check
the waterside balance during start-up and routine main-
tenance checks. Also, include strainers at each pump
inlet and unit. Install drain valves at the riser’s base to
allow drainage points for system flushing during start-
up and routine maintenance. For condenser draining
and header removal, include a shutoff/balancing valve
on the entering and leaving waterside pipes, drain tees,
and unions of each unit. Also, install a shutoff valve
on the unit entering water pipe for condenser draining.
Water Temperature Requirements
On units without a waterside economizer, do not al-
low the condensing water temperature to drop below
55.0°F. Water temperatures below this value causes the
compressors to shut down and the mechanical cooling
function locks out.
On units with waterside economizer the condensing
water temperature can drop to 50.0°F without effecting
the operation of the compressors.
