Laarsen Associates PW Manual Do Utilizador

Page 18

gas supply, the automatic safety shutoff devices must
be checked.
1.

Before beginning the tests, make sure the main
manual gas valve, and any other heater firing
valves are in the “OFF” position.

2.

Make sure the heater’s power switch is in the
“ON” position. After placing the manual pilot
gas valve in the open position and resetting all
safety devices, (high limit, pressure switch, low-
water cutoff, etc.) pilot(s) can be lit following the
procedure located on the heater rating plate.

3.

Once the pilot(s) is lit and has been established
for five minutes, the flame failure response time
should be checked as follows:

Systems 9 and 4 - (Intermittent ignition): With

this system pilots are automatically lit when the
operating controls call for heat. If the pilot flame fails
for any reason, the main valve is shut off within one
second and the pilot spark ignition is initiated until the
pilot flame has been reestablished. On propane
systems, unit locks out for safety. This sequence
should be checked by turning off the manual pilot gas
valve, and, at the same time, monitoring the audible
sparking at the pilot burner and signal interruption to
the main valve.

Propane gas is heavier than air and sinks to
the ground. Exercise extreme care in lighting
the heater when so equipped.

System 16 - (Electronically supervised standing

pilot system): Extinguish the pilot flame by placing
the manual pilot valve in the closed position, and at
the same time, begin recording the time it takes for the
output signal from the electronic ignition control to be
interrupted. The signal interruption can be detected
either with a test light or a voltmeter. The response
time should never exceed one second.

4.

With the pilots lit, initial activation of the main
burners can be achieved by slowly opening the
main manual valve. The result should be a
smooth lighting of the main burners.

After running the heater for a long enough

period, bring the water temperature within the range of
the hi-limit and slowly back off the high limit setting
until the heater shuts off. The main burners should
reignite when the hi-limit is reset and turned back up
to its original setting. The heater should now run until
it shuts off automatically on operating aquastat.

Be certain system pump is running, then proceed

as follows:

a.

Turn off main electrical switch.

b.

Turn off all manual gas valves and wait five
minutes (see Figure 19).

c.

Set operating control to lowest setting.

d.

Slowly turn manual gas valve to “ON”.

e.

Reset all safety valve switches (manual reset
high limit and low water cut off).

f.

Open manual pilot valve. Turn on main electrical
switch.

g.

Set temperature controller to desired
temperature. Pilot will light automatically to
ignite main burners whenever the aquastat calls
for heat.

For standing pilot system, press on pilot relay

knob, see Figure 20, light pilot and keep relay knob