Leslie Controls F-1240LDW Constantemp Double Wall Low pressure steam-water Heater - Manual (Page 11)

circulated water will assume a temperature of
110
0
F during prolonged periods when no water is
being used from heater. If a 180
0
F range unit is
used under the same conditions as above, the re-
circulated water temperature will rise to 180
0 F.
PROBLEM: EXCESSIVE DROP IN WATER
TEMPERATURE OCCURRING DURING OR AFTER
PROLONGED PERIODS WHEN NO WATER IS BEING
USED FROM HEATER AND RE-CIRCULATING
SYSTEM IS PROVIDED.
1.
Check for correct inlet steam pressure to heat
exchanger.
2. No water being re-circulated back to heater.
Check re-circulating system for proper operation
of pump, re-circulation valves and controls.
Heat Exchanger and Blending Valve
PROBLEM: DROP IN CONTROLLED WATER
TEMPERATURE OCCURRING BEFORE RATED
CAPACITY (GPM) OF YOUR HEATER IS OBTAINED.
1.
Check for correct inlet water operating pressure
and steam pressure to heater before and during
any operational test. LOW PRESSURE Heaters -
water pressure MUST be at least 5 psig ABOVE
maximum steam pressure used to operate Heater.
The MAXIMUM water pressure for all
Heaters is 150 psig.
NOTE: Seal plate (Part 45) must be tight seating to
prevent cold water from leaking into blended
water. This can cause an uncontrolled drop in
blended water adjusted temperature.
2.
Check to make sure all steam strainers are clean
and that all traps are functioning efficiently. A
flooded or partly flooded heat exchanger will
cause little or no heat transfer. Excessive back
pressure in trap discharge piping system, or partly
clogged piping can restrict flow of condensate
from Heater and cause flooding. Dirty or partly
plugged strainer screens can also cause this
problem.
The above system must be operating efficiently
before any check for fouled coils can be made.
3. To check for fouled coils, remove pipe plugs from
blending valve base and cover, and install a gauge
in each connection. Temperature of water from
heat exchanger outlet piping should be
approximately 200 to 215
0 F when heater is being
operated within its rated capacity. (Temperature
may be checked by using a contact Pyrometer
held against a smooth filed section of exchanger
outlet piping.)
Steam pressures of from 2 to 15 psig
may be checked by using the
CAPACITY AND ADJUSTMENT
TABLE found in your Heater Manual to
determine GPM and water temperature
per your operating conditions.
TEST PROCEDURE: With traps functioning
efficiently, and with flow adjusted for 60% of heater rated
capacity (approx. 5 psig differential across blending valve
diaphragm), the heat exchanger outlet water temperature
drops below 200¼F and continues to drop as flow is
increased to heaters rated capacity in GPM, it indicates
that coils are fouled and should be cleaned or replaced. A
coil cleaning Adaptor Kit is available through your Leslie
Representative, along with instructions for its use. If
quality of water being used for Heater is poor, coils may
foul rapidly indicating that corrective water treatment may
be necessary.
PROBLEM: INSUFFICIENT STEAM TO HEAT
EXCHANGER.
1.
See Paragraphs 1 and 2 above of trouble shooting
guide.
2.
Check steam reducing valve operation, if one is
used with Heater.
3.
PROBLEM: EXCESSIVE STEAM PRESSURE
TO HEAT EXCHANGER.
3.
Check steam reducing valve if one is used or
steam source supplying heater.
PROBLEM: EXCESSIVE RISE IN WATER
TEMPERATURE ABOVE HEATERS
SETPOINT OCCURRING AT LOW FLOWS.
1. The above problem may occur if Heater
Controlled Temperature is overset due to:
a. fouled coils
b. drop in inlet water supply pressure
c. adjustment of controlled water
temperature while exceeding Heaters
rated capacity in GPM.
See Paragraphs 1 and 2 of the second problem for
further information.
PROBLEM: EXCESSIVE DROP IN WATER
TEMPERATURE BELOW HEATERS
ADJUSTED SETPOINT OCCURRING
DURING LOW FLOW.
1. See Paragraph 1 of Problem 2 above.
2. Inefficient trap operation or increase in trap
discharge drain piping back-pressure. See
Paragraph 2 of Problem 3.
3. Too little gain. Readjust gain setting as shown in
Paragraph 2 of Problem 3.