H120 –H150 Hot Water Boilers
page 14
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To prevent rapid cycling of the boiler, the thermostat has an inbuilt time delay which
prevents the boiler from turning on for two minutes after the set point has been reached. If
the time delay is activated, the symbol “L” will be displayed. This is part of normal
operation.
•
The thermostat can be set to temperatures between 55˚C to 90˚C. (35˚C to 55˚C floor heat).
It also incorporates several safety features including a 100˚C high limit function to prevent
overheating. On simultaneous shut down of the circulating pump and boiler, the water within
the boiler may exceed the set temperature for a short period. If the pump and boiler are
restarted during this period, the thermostat will go into a standby mode and prevent the boiler
from relighting until the temperature within the boiler has dropped below the set
temperature.
•
If the optional set-back function is used, both set points (Set, Set 1) need to be adjusted
independently. These are each adjustable over the full thermostat range.
•
Should the thermostat fail to stop the boiler at the set point or at 100˚C, there is a manual
reset temperature limiting safety device designed to lock the boiler out and prevent further
heating. Plus a lock out condition is indicated by the symbols F1 or F2. To reset a lock out
condition, turn the controller off for five seconds. An F2 condition will first require the
mechanical safety device to be reset. To do this, remove the rear access panel and press the
red button. If the boiler has cooled sufficiently, a positive “click” should be heard and felt.
5.3.3 FAULT INDICATION
Under fault conditions the thermostat display will indicate a set of alpha numeric symbols to
indicate the status of the boiler. The meaning of each symbol and action to be taken are listed as
follows:
SYMBOL
MEANING
ACTION
Temp
Display
Unit has power.
No action
F0
Boiler locked off, thermistor wire is
disconnected or water at 0
°
C
(freeze conditions).
If water temperature reads greater than 0
°
C, turn
off/on if problem persists phone for service.
F1
Thermostat reads greater than
100
°
C or thermistor short circuited.
Allow water to cool, turn boiler off then on
again.
F2
Mechanical Hi Limit greater than
100
°
C.
Allow water to cool, reset Hi Limit, turn boiler
off then on again.
F5
Thermostat communication fault
Check connections. Check thermostat ‘type’
setting is correct.
L
Boiler locked out on time delay
No action. Boiler will delay for 2 minutes
Automatically reset after time delay. Or switch
off then on again for immediate ignition.
Pump operating & sufficient water
flow to operate boiler
No action.
Thermostat calling for heat
operating.
No action, boiler electronic ignition should
ignite in a few seconds.
Burner system has ignited and is
operating.
No action.
