31
Heater Coil Descaling Procedure
In time, a heating coil will accumulate lime or mineral scale deposits. The severity of lime or scale build-up will
depend on the hardness or mineral content of your water supply. As illustrated below, liming will first start in
the inner windings of a coil, then become less severe as it progresses through the outer coil windings. It is
possible for the inner coil windings to become partially clogged, and in some instances, completely plugged
before liming or mineral deposits can be noticed in fittings at the coil discharge outlet.
If your water has a high mineral content or hardness, a preventive maintenance schedule to descale the coil at
the end of each season, prior to winterizing, is recommended.
Before you begin
-- There are different types of coil cleaning chemicals. It is recommended you contact
Harvest Tec for the supply of the descaling kit, descaling chemicals, and instructions for use of these
chemicals. If this is not possible, the instructions below should be closely followed:
1. A sulfamic acid powder, containing a corrosion inhibitor should be used to remove lime and scale from coil.
2. In a clean 55 gallon drum (preferably plastic), mix approx. 25lbs of acid powder into 25 gallons of water.
3. Turn off the water supply. Disconnect the suction hose and return hose from the tank where they connect
to the rear of the dew simulator.
Connect the descaling kit suction line to the 2” inlet at the rear of the dew
simulator. Connect the descaling kit return line to the 3/4
” outlet at the rear of the dew simulator. Insert both
lines into the 55 gallon drum. Locate the end of the suction hose so the strainer is 3-4 inches above the
bottom of the container.
4. Prior to turning on the PTO, activate the Arm Override and Warmup Valve on the cab controller. This will
allow the cleaning solution to be circulated through the heater coils and be returned to the 55 gallon drum.
DO NOT ALLOW CLEANING SOLUTION TO REEL. Turn on the PTO and with it running at slightly higher
than an idle, circulate the acid solution through the system for 20-30 minutes. Whether the solution stops
foaming or not, do not circulate for more than 30 minutes. Soon after the solution has started circulation,
turn on Heater #1 and Heater #2 for approximately 10 seconds, then turn both heaters off. After 15 minutes
of circulation, turn on Heater #1 and Heater #2 for approximately 10 seconds, then turn both heaters off.
After circulation for 20-30 minutes total, turn off PTO.
5. Remove the acid suction hose from the rear of the machine.
Reconnect the 2” line from the water trailer to
the rear of the dew simulator. Remove the 3/4
” discharge hose from the 55 gallon drum and secure it to the
dew simulator frame so it is aimed at the ground. DO NOT ALLOW CLEANING SOLUTION TO REEL.
Ensure the tank has approximately 75-100 gallons of clean water in it, turn the water supply on. Turn the
PTO back on at an idle and pump clear water through the system for three to four (3-4) minutes. Turn the
PTO off.
6. Add one pint of household ammonia to the water in the tank. Reconnect the tank return line to the rear of
the dew simulator. Turn the PTO on at approximately 700rpm and circulate this solution back into the tank
for approximately five (5) minutes, then turn PTO off.
Turn off the 2” valve and disconnect the suction line
from the dew simulator. Open the valve and drain on ground. Close valve when done and reconnect to
machine.
7. Refill tank with approximately 75-100 gallons of clean water.
Turn 2” valve on. Disconnect the tank return
line and reconnect the descaling discharge line, once again securing it so it is aimed at the ground. Turn
the PTO back on at 700rpm and flush the system with clean water, discharging onto the ground for about 5
minutes or until the supply tank is empty. Turn off PTO and deactivate the Arm Override and the Warmup
valve on the cab controller.
CAUTION: Coil cleaning acids or chemicals are hazardous. Protective gloves, clothing, and safety glasses and
face shield should be worn when handling. Dispose of drum contents (used acid solution) accordingly.
Summary of Contents for 720 Dew Simulator
Page 2: ...2 intentionally blank...
Page 7: ...7 Safety Decal Locations...
Page 69: ...69 Notes...
Page 70: ...70 Notes...