14
Time to Produce 2nd & 3rd
Temperature Setting
Degree Burns on Adult Skin
VERY HOT= approx. 160*F
About 1/2 second
C = approx. 150*F
About 1-1/2 seconds
B = approx. 140*F
Less than 5 seconds
A = approx. 130*F
About 30 seconds
HOT = approx. 120*F
More than 5 minutes
LOW = approx. 80*F
- - - - - - - - - - - - - - - -
FIGURE 9
Valves for reducing the point-of-use temperature by mixing cold
and hot water are available. See figure 2. Also available are
inexpensive devices that attach to faucets to limit hot water
temperatures. Contact a licensed plumber or the local plumbing
authority.
SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL
TO SHUTOFF, TURN OFF THE MANUAL GAS CONTROL VALVE
TO THE APPLIANCE. SEE FIGURE 1(G).
WATER HEATING IGNITION SEQUENCE
(Make sure gas and electric power are connected properly)
1) The ignition control module is powered and monitors the
system, waiting for a call for heat from the thermostat.
2) The thermostat calls for heat by reading a resistance value
within a given range directly proprtional to water temperature.
3) The control Module:
a) Checks the pressure switch for an open circuit.
b) Energizes the blower.
c) Checks the pressure switch for a closed circuit to prove
draft.
d) Sends line voltage to the hot surface igniter with a 7-second
warm up period.
e) Opens the gas valve and checks the sensing rod for flame.
4) The burner heats the water to the desired thermostat setting.
a) The resistance in the thermostat rises to the value selected
by the temperature control knob.
b) The control module closes the gas valve and 5 seconds
later, removes power from the blower.
5) Cycle is completed.
FIGURE 10
CONTROL SEQUENCE - HOT SURFACE DIRECT IGNITION
Pre-purge
5 sec.
HSI Warm-up
7 sec. 1st try, then 12 sec.
Ignition Activation Period
3 sec.
Flame Recognition Period
1sec.
Ignition Trial
4sec.
Interpurge
30sec.
Post-purge
5sec.
Retries
3
Reset from Lockout
1 hr.
Flame Sensing (Nominal)
HSI Off/Run Mode
0.4µ
