Description of functioning
t e c h n i c a l
13
92º C Security (without DHW demand)
If heating thermistor value arrives to 92º C, the pump
will run
making cycles of 10 se-
cond
starting
and stop
p
ing. If the temperature remains high the pump will continue
cycling until
a lower temperature is detected.
180 minutes security:
When the burner is working continuously for 180 minutes, the burner
will shut down
for a
period
and if it is necessary, the
burner will relight.
Control and safety components:
Main PCB
:
This circuit governs the correct functioning of all the boiler
functions
.
High limit
thermostat:
(Part number MCB2250)
This is in direct contact with th
e
the main heat exchanger (
dry pocket)
It controls the temperature of the outlet circuit, protecting the boiler against overhea-
ting. It cuts out at 102º C.
The contacts of this thermostat are normally closed. When the thermostat is activa-
ted, the boiler will
lock out
(F4 block). The thermostat resets automatically,
although the F4
fault will need resetting from the control panel.
Thermistors:
There are two thermistors incorporated to the boiler.
The DHW thermistor is screwed
into the 3 way valve at the hot water outlet, and is in direct contact with the hot water
exiting the boiler. (Part number FCB1080 ) faulty or out of range
thermistors will cause the boiler to lock out with F11.
(N.B. the boiler
will only read the values of this thermistor when working in hot
water mode)
The central heating thermistor is located on the left hand side of the
primary heat exchanger. This thermistor controls the temperature of
the primary circuit within the boiler.
The thermistor is also responsible for first stage over heat protection
any overheating within the boiler is detected and controlled by the pump
cycling in 10 second intervals until a lower value is reached.
The thermistor also reads the temperature for the built in frost protection.
Faulty or out of range thermistors will cause the boiler to lock out (F13)
(Part number MCB2245)
FCB1080
DHW
C.H.
HL STAT
12
MCB2245