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With summer upon us, your drycleaning machine’s cooling system will be under greater
stress.
It doesn’t matter if you are using
a water tower, chiller or city water
for cooling, conditions 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
cycle. 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. Some of the
newer models and the K4 machines use R400 Freon as refrigerants) and some form of 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 cooled
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 condensed by
water (called a coolant).
In this case we are transferring the heat from a vapor rich, hot, compressed Freon gas to the
coolant flowing through the refrigeration condenser.
Three methods of supplying coolant 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 machines refrigeration
condenser over an evaporative cooling media (looks like corrugated plastic tubes) which has air
forced though aiding in evaporation, then 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 water which
drops into the sump for recirculation through the drycleaning machines refrigeration condenser.
3. Chiller. water or a mixture of water and glycol (this mixture is called a brine) is circulated
by a pump through the drycleaning machines refrigeration condenser; cooled by a separate
refrigeration system; re-circulated through the drycleaning machines refrigeration condenser.
No matter what method is used for cooling and circulating the coolant through the
refrigeration condenser, the efficiency of the process is dependent on two factors:
• Coolant flow, the amount of coolant moving through the condenser.
• Heat transfer efficiency, the ability of the condenser to move heat to the coolant.
Each of the above factors can be easily monitored using pressure and temperature as
indicators of what is going on in the coolant system.
A pressure gage and thermometer at the inlet and outlet of the coolant system located near
the drycleaning machine are vital for monitoring the cooling system performance.
The pump must supply enough pressure as well as flow in sufficient quantity to push coolant
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 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 should be.
The best method for obtaining the “numbers” is to note the drycleaning machine inlet and
outlet pressure and temperature readings for future reference when the drycleaning machine is
working properly.
Let’s have a look at what the thermometers and pressure gages can tell us about the
condition of the coolant system.
The following are some possible scenarios for different combinations of qualitative data:
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
drycleaning machine.
B. Heavy scale build up — a build-up of scale 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 is off.
B. Clogged inlet strainer.
5. High inlet temperature/
high outlet temperature:
A. Water tower fan not working; chiller refrigeration system faulty.
B. Pump is off.
6. Slightly higher than normal inlet temperature/high outlet temperature:
A. Heavy scale build up — a build-up of scale inside the piping of the drycleaning machine.
B. Excessive heat source — still boilover 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
mode.
During the drying mode, the heat exchanger coil is transferring much of the heat from the
Freon to the air stream and only a small portion of the heat load is being dumped into the
refrigeration condenser.
In the cool down 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 high-pressure
condition and tripping the refrigeration high pressure safety switch.
Most of the time this would cause an error message on the programmer screen and require a
manual rest of the refrigeration high pressure safety switch. This condition is almost always
caused by either a clogged Y strainer or excessive scaling inside the refrigeration condenser.
On most drycleaning machines, there is a refrigeration head pressure adjusting valve which
controls the refrigeration head pressure by varying flow of coolant to the refrigeration
condenser.
This valve is adjusted to give sufficient refrigeration head pressure for efficient refrigeration
system operation.
When scale builds up in the refrigeration condenser past the point where the normal
adjustment of the head pressure adjusting valve can compensate, many drycleaners simple
open the valve wider in the very mistaken belief they have actually fixed something. What they
have done is “kicked the can down the road” and will pay a lot of extra money in solvent and
energy for the privilege.
The accompanying illustrations show schematics for typical cooling water installations on
systems using a water tower or chiller.
The top half of the illustration is what is most commonly found; the bottom portion is an
installation 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 not only an emergency back-up for continuing operations
when there is a failure in the normal cooling system as well as ready access for connecting a
descaling pump.
Hot weather cooling problems

Bruce Grossman is the
chief of R&D for EZtimers
Manufacturing, a
company that offers
several products for
testing and protecting a
plant’s boiler and steam
system — the Sentinel,
EZ-Level and Tattler
steam trap tester. Also,
the company has a line
of separator water
processing and disposal
equipment for
drycleanings machine
using any type of solvent
— the Sahara and Drop
in the Bucket misters.
Questions can be
addressed to
bruce@eztimers.com or
call (702) 376-6693.
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