ECH EVAPORATIVE CONDENSERS
OPERATION
140.910-IOM (DEC 13)
Page 10
across all cells. During prolonged periods, bypass the idle units
and drain the basins.
Multi-Speed Motors
: If the unit is equipped with 2-speed mo-
tors or Sentinel™/Sentinel PLUS™ Fan System, operation at a
lower speed may be sufficient to prevent icing. When 2-speed
motors are used, the motor starter should include a minimum
15 second time delay when switching from high to low speed.
Variable Frequency Drives
: VFDs offer the most precise method
of capacity control, by modulating fan motor speed. When us-
ing VFDs, avoid operating at or near “critical speeds.” Units
with VFDs require inverter duty motors which are included as
standard.
In subfreezing ambient temperatures, cycle the fan off for 5
minutes every 15 to 20 minutes for each cell. If ice continues
to build on the louvers, decrease the on-time. Observe inlet
louvers every 4 to 8 hours.
NOTICE
Modulating the water flow rate to the unit is NOT a recom-
mended method of controlling cooling capacity.
Coil Freeze Protection
Use an industrial grade inhibited glycol solution for protection
against coil freeze-up. When the use of glycol is not practical,
the system must be designed to meet both minimum flow and
minimum temperature requirements.
•
Recommended solutions are an industrial grade inhibited
ethylene glycol or propylene glycol solution.
•
Coil volume for condenser models using liquid cooling
circuits is job specific.
Minimum Operation
When a glycol solution is not utilized, operate the system to
meet both of the following conditions.
•
Maintain the minimum recommended flow through the coil
at all the times per the job specifications.
•
Maintain a minimum heat load on the circulating fluid so
that the temperature of the fluid leaving the coil will not
fall below 50°F (10°C).
•
To maintain the leaving fluid temperature at 50°F (10°C)
when the process load is extremely light or shut off, apply
an auxiliary heat load to the circulating fluid.
Positive Closure Damper Hood and Insulation
The amount of auxiliary heat required can be substantially re-
duced by the use of a positive closure damper hood and insula-
tion. The heat loss data can be found in publication 140.910-SED.
Emergency Coil Drain
Do not drain the coil as a normal method of freeze protection.
Frequent draining promotes corrosion inside the coil tube.
However, draining is acceptable as an emergency method of
freeze protection if the coil is not protected by a glycol solu-
tion. If the coil is not protected, an automatic drain valve and
vacuum breaker are recommended to drain the coil if flow
stops or fluid temperature drops below 50°F (10°C) when the
ambient temperature is below freezing. Contact your local Frick
Representative for guidelines on the installation of an emergency
coil drain system.
•
Further protection against coil freeze-up is possible with
the installation of an alarm to alert personnel when the
temperature of fluid leaving the coil falls below 50°F (10°C).
•
For evaporative cooling applications only, the glycol
solution will maintain the leaving fluid temperature as low
as 45°F (7.2°C). Contact your local Frick Representative for
necessary precautions.
Basin Water and Internal Piping Freeze Protection
Cold Water Basin Protection
The basin water could freeze when the unit is shut down and
exposed to subfreezing ambient temperatures.
Indoor Sump
: The ideal method of protection is a remote sump
located in a heated indoor area. When the circulating pump
stops, the water in the connecting piping will drain by gravity
to this indoor sump.
Basin Heaters
: On applications without a remote sump, provide
heat to the cold water basin. Electrical immersion heaters, steam
coils or hot water coils can provide the required function. Contact
your local Frick Representative for details.
Electric Water Level Control
: An electric water level control will
maintain the proper water level regardless of the thermal load or
variations in makeup water supply pressure. The two-position,
slow closing solenoid valve provided in the Frick electric water
level control package also minimizes valve freezing problems.
Heat Tracing
: Heat trace and insulate all exposed water piping,
including pump piping below the overflow level and makeup
water lines, with electrical heater tape.
Piping Freeze Protection
•
Eliminate all water in the optional SmoothLink™ Piping
Arrangement.
•
It is essential to drain water from the SmoothLink™ Piping
Arrangement and internal piping whenever the potential
for freezing temperatures exits. Drain the water by using
1/2” NPT drain port located on the inboard side of the
SmoothLink™ Piping Arrangement.
•
There are three recommended methods for draining the
piping:
1. Preferred: Install a normally open 1/2” solenoid valve
on the 1/2” drain connection of the SmoothLink™
Piping Arrangement. Wire the valve in the pump circuit
such that the valve closes when the pump is energized.
Select the solenoid valve to operate with a minimum
pressure differential of 0 psi, which is required to limit
the static head imposed on the valve from the water
column.
2. Install a 1/2” manual valve on the 1/2” drain connection
of the SmoothLink™ Piping Arrangement.
Open the valve during the cold weather operation.
Keep the valve closed during the warm weather to
achieve full thermal performance.
3. Remove the 1/2” plug from the 1/2” drain connection
of SmoothLink™ Piping Arrangement during the cold
weather operation. Reinstall the plug during the warm
weather to obtain full thermal performance.
