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19
DANGER
HOT WATER TEMPERATURES REQUIRED FOR AUTOMATIC
DISHWASHER AND LAUNDRY USE CAN CAUSE SCALD
BURNS RESULTING IN SERIOUS PERSONAL INJURY AND/
OR DEATH. THE TEMPERATURE AT WHICH INJURY OCCURS
VARIES WITH THE PERSON’S AGE AND TIME OF EXPOSURE.
THE SLOWER RESPONSE TIME OF CHILDREN, AGED OR
DISABLED PERSONS INCREASES THE HAZARDS TO THEM.
NEVER ALLOW SMALL CHILDREN TO USE A HOT WATER
TAP, OR TO DRAW THEIR OWN BATH WATER. NEVER LEAVE
A CHILD OR DISABLED PERSON UNATTENDED IN A BATHTUB
OR SHOWER.
THE WATER HEATER SHOULD BE LOCATED IN AN AREA
WHERE THE GENERAL PUBLIC DOES NOT HAVE ACCESS
TO SET TEMPERATURES.
It is recommended in domestic hot water applications that lower
water temperature be used to avoid the risk of scalding. It is
further recommended, in all cases, that the water temperature be
set for the lowest temperature which satisfies the user’s hot water
needs. This will also provide the most energy efficient operation
of the boiler and minimize scale formation in the heat exchanger,
thus prolonging the life of the boiler.
SETTING THE WATER HEATER TEMPERATURE AT 120°F
(49°C) WILL REDUCE THE RISK OF SCALDS. Some states
require settings at specific lower temperatures. The table below
shows the approximate time-to-burn relationship for normal adult
skin.
Temperature Time to Produce 2nd & 3rd
Setting Degree Burns on Adult Skin
Over 170°F (77°C) Nearly instantaneous
160°F (71°C) About 1/2 seconds
150°F (66°C) About 1-1/2 seconds
140°F (60°) Less than 5 seconds
130°F (54°) About 30 seconds
120°F (49°C) or less More than 5 minutes
Table 7
USE ANTI-SCALD VALVE(S) in the hot water system to reduce
the risks of scalding at points of use such as lavatories, sinks and
bathing facilities.
CAUTION
IN THE EVENT OF ELECTRIC POWER FAILURE, DO NOT
ATTEMPT TO OPERATE THE HEATER.
CHECKING AND ADJUSTING THE INPUT
The maximum inlet gas pressure must not exceed the value
specified by the manufacturer (10.5" W.C. - natural gas,
13.0" W.C. - propane gas). The minimum value listed on the
Rating Plate is for the purposes of input adjustment.
1. Turn the gas valve control knob to “OFF”, (See page 18).
2. Attach a pressure gauge or a manometer to the outlet pressure
tap, figure 14 and refer to table 3 for correct manifold pressure.
3. Fire the heater by turning the gas valve control knob to “ON”.
4. Use this formula to “clock” the meter. Be sure that other gas
consuming appliances are not operating during this interval.
3600
T x H = Btuh
T = Time (in seconds) to burn one cubic foot of gas.
H = Heating value of gas (in Btu’s per cubic foot of gas).
Btuh = Actual heater input (in Btuh).
EXAMPLE: (Using HW-120M heater)
T = 31.5 seconds/ft
3
H = 1050 Btu/ft
3
Btuh = ?
3600 x 1050 = 120,000 (compare with the ratings in
31.5 Table 5).
Should it be necessary to adjust the gas pressure to the burners
to obtain the full input rate, the steps below should be followed.
5. Remove the regulator adjustment sealing cap, fig. 14, and
adjust the pressure by turning the adjusting screw with a
screwdriver.
• Clockwise to increase gas pressure and input rate.
• Counterclockwise
to decrease gas pressure and input
rate.
DO NOT turn the adjusting screw in past the point of little or no
manifold pressure change or fully bottom the adjusting screw.
6. “Clock” the meter as in step 4 above.
7. Repeat steps 5 and 6 until the specified input rate is achieved.
8. Turn the gas valve control knob to “OFF”. Replace the regulator
adjustment sealing cap and remove the pressure gauge or
manometer from the outlet pressure tap. Using an allen
wrench, replace the set screw in the outlet pressure tap.
9. Turn the gas valve control knob to “ON”.
If gas pressure regulator cannot be equipped to give the full input
rating with sufficient gas pressure at the valve, re-orifice the main
burners.
IMPORTANT
UNDER NO CIRCUMSTANCES SHOULD THE GAS INPUT
EXCEED THE INPUT SHOWN IN TABLE 2. OVERFIRING
COULD RESULT IN DAMAGE OR SOOTING OF THE HEATER.
When the heater is operating at full capacity, or full gas input, it
should consume 1 cu. ft. of gas in approximately the amount of
time indicated in table 8.
TABLE 8 — TIME REQUIRED TO CONSUME 1 CUBIC FT. OF GAS
(Heater operating at full input or full capacity.
Does not apply to high altitude installations.)
Heating Total Time Required (Seconds)
Value MODEL
Type of (Btu/
Gas Cu. Ft.) HW-120M HW-160M HW-200M HW-225M
Natural 1050 31.5 23.6 19.0 16.8
Propane 2500 78.3 56.3 45.2 - - -