Installation manual

installation manual TWIN 80 EN
27
CHAPTER 4. FAULT FINDING
4.1 Boiler states
Burner is on - when the room thermostat is closed (heat demand)
- and when the actual flow temperature is 5°C below the set point (desired central heating flow temperature)
- and after 3 minutes anti-cycling time, if applicable, after a reciprocal stop.
Burner is off - when the room thermostat is open (end of heat demand)
- when the actual flow temperature is 3°C above the set point (blocking)
- or when the actual flow temperature is 3°C above the maximum permissible central heating temperature.
Standby Pre rinse Ignition Heat operate Post rinse
Pump
after run
Standby
heat demand
fan
gas valve
glow plug
ionisation
pump
t=0sec t=3sec t=7sec t<12sec
4.1.1. Standby
(Fan off - Gas valve off - Glow plug off - Ionisation off)
No heat demand.
Heat demand: During the standby, a check is made to see if
there is heat demand. If so the boiler will go over to “pre rise”.
No heat demand:
If the difference between flow and return
temperatures is larger than ± 5°C, once per hour, the pump will
be switched on for a maximum of 10 minutes to see whether
the temperature difference goes to within ± 5°C.
4.1.2. Pre rinse
(Fan on - Gas valve off - Glow plug on - Ionisation off)
Combustion chamber is being pre-ventilated with air from the
burner fan(s).
Fan: The fan is switched on at the purging speed (1350 rpm).
Glow plug: The glow plug is switched on at the same time as
the fan.
Pump test:
The pump is switched off for 3 seconds and the
water pressure (static pressure) is measured. Then the pump is
switched to high speed and the water pressure (active pump
pressure) is also measured. If the difference between the active
pump pressure and the static pressure is between 0.05 bar and
0.54 bar (0.64 for type 40 / TWIN) a correct water flow through
the heat exchanger is present and the “ignition time” starts. If
the pressure difference is outside this range, the pump test
repeats each 15 seconds.
4.1.3. Ignition
(Fan on - Gas valve on - Glow plug on/off - Ionisation
off/on)
The ignition sequence of the burner is initiated.
Fan: The fan is running at the ignition speed (2900 rpm).
Gas valve:
The gas valve coil is activated and opens the safety
valves.
Glow plug:
The glow plug ignites the gas/air mixture from the
burner.
Ionisation:
As soon as an ionisation signal is measured, the
glow plug is switched off and the boiler will go over to “in
operation”. If there is no ionisation signal at the end of the
safety time, a new start attempt is made, if this was not the last
permitted (fourth) attempt.
4.1.4. heat operate
(Fan on - Gas valve on - Glow plug off - Ionisation on)
The burner is on in heating mode.
Temperature test: To ensure the water flow through the heat
exchanger a temperature test is activated. After each burner
start, the difference between flow and return temperatures must
be raised by 3°C within 20 seconds. If not, the boiler makes a
restart. Eventually, after three restarts, the boiler runs into lock-
out.