With summer upon us your, drycleaning machine’s cooling system will be under greater
It doesn’t matter if you are using a water tower, chiller or city water for cooling,
that weren’t an issue during the cooler months may become problems as the ambient
(surrounding) temperature rises.
Most of the cooling problems will
rear their ugly heads during the
drying segment of the drycleaning
Drying in the drycleaning machine
sense is all about moving heat
energy. The media which moves all
this heat is called a refrigerant (most
machines use R22 Freon while some
of the newer models and the K4 machines use R400 Freon as refrigerants) and some
coolant (generally water or a water and glycol mixture.)
It doesn’t matter which Freon is used, the process itself requires a device called a
refrigeration condenser which changes hot, vapor rich, Freon gas back into
liquid Freon which is
constantly being recycled during the drying segment of the drycleaning cycle.
In almost every case, this condenser is cooled by a liquid (there are a few air
condensers which are not the topic of this article). Hot, compressed Freon gas
is forced by the
refrigeration compressor into the refrigeration condenser where it is cooled and
water (called a coolant)
In this case we are transferring the heat from a vapor rich, hot, compressed
Freon gas into
the coolant flowing through the refrigeration condenser.
There are three methods of supplying water to the refrigerated condenser
1. City water. Water from the city main is forced through the drycleaning machine’s
refrigeration condenser propelled by existing city water pressure. The exiting
water is then sent
down the drain.
2. Water tower. Water is circulated by a pump through the drycleaning machine’s
refrigeration condenser; over an evaporative cooling media (looks like
corrugated plastic cubes)
which has air forced though it to aid in evaporation; into a sump where the
suction inlet of the
pump is connected.
The evaporation of the water from the surface of the media cools the remaining
drops into the sump for recirculation through the drycleaning machine’s refrigeration condenser.
3. Chiller. Water or a mixture of water and glycol (this mixture is called a brine) is
by a pump through the drycleaning machine’s refrigeration condenser; cooled by a separate
refrigeration system; then recirculated through the drycleaning machine’s refrigeration
No matter what method is used for cooling and circulating the coolant through
refrigeration condenser, the efficiency of the process is dependent on two
• Coolant flow. The amount of coolant moving through the condenser.
• Heat transfer efficiency. The ability of the condenser coil to move heat to the
Each of the above factors can be easily monitored using pressure and temperature
indicators of what is going on in the coolant system.
A pressure gage and a thermometer at the inlet and outlet of the coolant system
the drycleaning machine are vital for monitoring the cooling system performance.
Let’s take a look at what the pressure gage can tell us about the condition of the
The pump must supply enough pressure as well as flow in sufficient quantity to
through the components that require cooling on the drycleaning machine.
On most machines this would include not only the refrigeration condenser but
also the still
condenser and solvent cooler. In the case of water towers and chillers, also
enough pressure to
push it back to the tower or chiller sump which are often located on the roof.
Unfortunately there is no hard and fast rule for what the pressure readings
The best method for obtaining the “numbers” is to note, for future reference, the drycleaning
machine inlet and outlet pressure and temperature readings when the drycleaning
working properly .
The following are some possible scenarios for different combinations of
1. Inlet pressure high/outlet pressure low:
A. Check for blockage of the inlet flow path, a clogged Y strainer between the
pump and the
B. Heavy scale build up inside the piping of the drycleaning machine.
2. Inlet and outlet pressure rapidly changing:
A. Low coolant level in the pumping system.
3. Low inlet/high outlet pressure:
A. Open bypass valve on pumping system.
4. Low inlet/low outlet pressure:
A. Pump off.
B. Clogged inlet strainer.
5. High inlet temperature; high outlet temperature:
A. Water tower fan not working; chiller refrigeration system faulty.
B. Pump off.
6. Slightly higher than normal inlet temperature/high outlet temperature:
A. Heavy scale build up inside the piping of the drycleaning machine.
B. Excessive heat source — still boil over or steam sweep valve open; steam supply
valve to steam boost coil or carbon adsorber.
Back to the drycleaning machine operation.
Problems with the cooling system are most likely to appear during the dry cycle.
To be more
specific, towards the end of the dry cycle when the drycleaning machine goes
into cool down
During the drying mode the heat exchanger coil is transferring much of the heat
Freon to the air stream and only a small portion of the heat load is being
dumped into the
In the cooldown mode, solenoids and dampers change and almost the entire heat
load is now
dumped into the refrigeration condenser.
This type of problem is indicated by the refrigeration compressor going into a
condition and tripping the refrigeration high pressure safety switch.
Most of the time this would cause an error message on the programmer screen and
manual rest of the refrigeration high pressure safety switch. This condition is
caused by either a clogged Y strainer or excessive scaling inside the
On most drycleaning machines there is a refrigeration head pressure adjusting
controls the refrigeration head pressure by varying flow of coolant to the
condenser. This valve is adjusted to give sufficient refrigeration head pressure
refrigeration system operation.
When scale builds up in the refrigeration condenser past the point for which the
adjustment of the head pressure adjusting valve can compensate, many drycleaners
open the valve wider in the very mistaken belief they have actually fixed
What they have actually done is “kicked the can down the road” and pay a lot of extra money
in solvent and energy for the privilege.
The accompanying illustration shows a schematics for a typical cooling water
use with a water tower or chiller with the addition of valves 1,2,3 which are
used when a city
water hook-up is included in the installation. This city water hook-up provides
back-up for continuing operations when there is a failure in the normal cooling
system It will not
help if excessive internal scaling is the cause of the problem.