Midco DS24A - Manual (Page 6)

WARNING: When rein-
stalling the curved manifold
pipe, make sure the manifold
slide plate is positioned in its
holder and that the main spud is
inserted into the end of the noz-
zle, see Figures 6 and 7.
Reconnect union and replace back-
plate.
WARNING: Reposition the
combustion air shutter for the
maximum firing rate of the
selected spud capacity range. Do
not change the Combination Valve
Gas Pressure Regulator setting at
this time.
CAUTION: The approximate
air and gas settings described above are for initial start-up only. Final settings must be
made in accordance with Section VIII, Initial StartUp/Adjustment Instructions for adjust-
ment of the manifold gas pressure are detailed in Section XI, Combination Gas Valve.
WARNING: Ignition is automatic. Make spark observations into combustion chamber
only with Main Manual Shut-Off Valve closed. Confirm that gas utilization equipment
does not contain any accumulated gases. Purge as described in Step 3 below.
1.
Check the burner piping and valves for gas leaks by applying a weak liquid soap solution to
unions and joints with the gas supply on. Leakage will be indicated by the appearance of soap
bubbles. Locate and correct all gas leaks before proceeding.
WARNING: DO NOT USE OPEN FLAME.
2. Purging the air from the gas supply line at this step will expedite the first light-off.
CAUTION: Purge outside the building. Do not purge into the gas utilization equip-
ment.
3.
To purge the gas utilization equipment and chimney of any accumulated gases, turn Manual
Gas Cock Knob on the Combination Valve to OFF, turn burner power on and set the operating
control to ON or thermostat to call for heat. Let the blower run long enough to accomplish four
air changes, but not less than five minutes.
4.
CAUTION: Make sure that the capacity range of the installed spud and the prelimi-
nary combustion air shutter setting are suitable for capacity rating of the gas utilization
equipment. Refer to Section VII, Main Gas Spud and Table 3.
5.
RESET the Electronic Control by setting the operating control to OFF or the thermostat
below room temperature for at least 30 seconds, see Section XII, Electronic Control.
6.
Confirm that Main Manual Shut-Off Valve is open. Turn Manual Gas Cock Knob on
Combination Valve to ON.
7.
Turn operating control to ON or set thermostat above room temperature. Main flame should
come on when the motor reaches operating speed (after a 30 second prepurge in Canada).
Whenever the burner fails to light during the 6-second ignition trial, or if the flame is lost during
the burner run and not re-established within 6 seconds, the Electronic Control will shut off the
Combination Valve and LOCK OUT. To RESET the Control for restart, de-energize the Electronic
Control by setting the operating control to OFF or thermostat below room temperature for at
least 30 seconds. If burner still fails to light, turn it off and repeat from Step 5 above. Then if nec-
essary, refer to the Trouble Chart to isolate the problem.
WARNING: Repeated unsuccessful attempts to light will result in accumulated gases
in gas utilization equipment and chimney. To prevent these gases from reaching an
explosive level, periodically purge the gas utilization equipment and chimney as
described in Step 3.
8.
To make a preliminary setting of the burner input, determine the manifold gas pressure
required from Table 3 and adjust the Combination Valve pressure regulator accordingly, see
Section XI, Combination Gas Valve.
9.
To determine the firing rate for NATURAL gas, accurately time test dial for the number of
seconds for one revolution and use the following formula. All other gas utilization equipment
must be off.
Then divide by 1,000 for MBH value:
VIII Initial
StartUp/Adjustment
3600 x test dial size x BTU value
No. of seconds for one rev. test dial.
= BTU/Hr.
3600 x 1 x 1000
20
= 180,000 BTU/Hr. = 180 MBH Example:
Table 3: Main Gas Spud Capacity and
Preliminary Gas and Air Settings
6
VII Main Gas Spud
Continued