Patterson-Kelley MACH-05 ユーザーズマニュアル

 

Page  32 

 
1.  When the On/Off (Main power) switch is turned 

on,  power is provided through a circuit breaker to 
the boiler control and the combustion blower.  The 
boiler control powers a 24 V transformer.  The 
boiler control supplies 24 V power through a high 
limit temperature switch and a low water level 
control.  

2.  The low water level control is closed when there is 

water in the boiler up to the probe. 

3.  When the temperature sensed by the high limit 

temperature control is below the set limit, the 
switch is closed.  Manual reset of the switch is 
required following conditions exceeding high limit 
temperature.  

4.  If either the high limit temperature control or the 

low water level control is open, the boiler control 
locks out and indicates E 12 on the display. 

5.  Depending on the settings in the boiler control, a 

heat request is generated.  

6.  The controller checks that the low air pressure 

switch is open indicating no airflow.  The blower 
is driven towards the prestart fan speed.  When the 
air pressure switch closes the 15 second prepurge 
time is started, and the blower is driven toward the 
ignition speed.  

7.  After the 15 second prepurge the gas pressure 

switch circuit is checked to ensure the gas pressure 
is within design parameters. 

8.  If there are no lockouts then when the blower 

speed is within 200 rpm of the ignition fan speed, 
a trial for ignition period of 3 seconds is initiated. 
The internal spark generator and the gas safety 
shut off / control valves are energized. 

9.  The internal spark generator is de-energized .3 

seconds before the end of the trial for ignition 
period. After the trial for ignition period, if a flame 
signal is detected by the flame rectification 
system, the control initiates a flame stabilization 
period of 5 seconds at the ignition rpm of the fan. 
The fan is driven to low fire for 1 minute before 
the boiler is released to modulation. 

10.  The unit modulates between the low fire setting 

and the high fire setting to maintain the desired 
outlet water temp set point. 

11.  When the load is below the low fire rating of the 

boiler the boiler will continue firing and the outlet 
water temperature will rise until it reaches the set 
point + temperature differential.  At this point the 
burner is turned off, and the fan continues to run to 
post purge the boiler for 15 seconds. 

12.  When the water temperature is reduced by the load 

on the system, a heat request is again generated. 
The operating sequence will recycle to step 6, 
provided the limits on water level, gas pressure 
and high temperature are all met. 

 

 

 
The MACH Series boiler will display service codes to 
indicate some problems with the boiler.  There are two 
types of lockouts the control may experience: manual 
reset lockouts requiring an operator to press the reset 
button, and automatic reset lockouts, where the control 
will automatically attempt to restart the boiler.  A 
listing of service codes is included at the end of this 
section. 

Should the unit fail to operate, call a qualified service 
technician to troubleshoot the problem and implement 
corrective action. 

 

In the event of a power failure (or when the On/Off 
switch is in the Off position), the display panel is not 
illuminated and the entire system is de-energized, 
closing all automatic valves and halting all boiler 
operations.  When power is restored the sequence of 
operation will resume at Step 5, provided that all the 
limits are satisfied. If any manual reset lockout was 
present when the power is lost, the display will flash E 
04 when the power is resumed.  This indicates that the 
control was in lockout mode but does not indicate 
which service code was present.