14
Control Details
The control box is located at the top front of the boiler and encloses the appropriate thermostats.
Check that it also contains the correct wiring diagram.
Control Details
• Burner control circuit switch:
Switching the boiler ON:
Setting the switch to the On position will allow the
boiler to be switched on/off by any external controls,
e.g. time switch. When external controls are in the
ON position, the boiler will switch on/off at the
dictates of the control thermostats.
In the case of a gas burner if the boiler has been
off for a long period,or the gas supply has been
disconnected, ensure gas is purged to the boiler,
and the main pilot gas cocks are turned on before
switching to the ON position.
• Limit thermostat:
The maxiumum setting of the limit thermostat is 110
o
C.
The limit thermostat should normally be set 10
o
C
above the control thermostat (access to the limit
thermostat adjustment is gained from inside the
control panel (isolate electrical supply before
removing control panel cover). Note: Once turned
down, the limit thermostat
cannot
be turned up to
a higher temperature). If the boiler temperature
exceeds this, the boiler will be switched off and the
high temperature cut out light will be illuminated (the
boiler will not operate until the limit thermostat is
manually reset).
•
High temperature cut out light
If the high temp cut out light is illuminated, the limit
thermostat will need to be manually reset. Allow
the boiler to cool down, then unscrew the protective
cover of the reset button. Press the button in and
replace the cover. The boiler will automatically
resume operation. If there are repeated faults,
contact the Hoval Service Department.
• Burner lockout light:
If the burner lockout light is illuminated, the
burner control will have gone to lockout. To rectify
this, press the illuminated button on the burner
control box. If the burner goes to lockout several
times in a short period, contact the Hoval Service
Department.
• Terminals
Terminals are provided in the control panel for linking
in additional controls e.g. time switch, pressurisation
unit, interlocks etc.
The control panel (as illustrated) is generally supplied for mounting on top of the boiler casing by the installer.
For normal high/low operation the control stat is set by the Hoval commissioning engineer at the required lev-
el e.g. 80
o
C . The limit stat will be set at a minimum of 6
o
C above this and the high/low stat at 3 to 5
o
C below
the operating stat setting (where fitted). For other special requirements refer to the wiring diagram. A flexible
lead is provided from the control panel which has to be wired into the burner terminals by the Installer prior to
commissioning. (See important note below)
• Control thermostat:
The control thermostat should normally be set in
the range 70-83
o
C. It can, however, be set higher,
up to 100
o
C maximum.
Access to the control thermostat adjustment is
gained by removing the circular disc on the front
of the control panel.
1 6 7 8
Key
1. Burner control circuit switch
2. Burner run light
3. High fire run light
4. High temperature cutout light
5. Burner lockout light
6. Control thermostat adjustment
7. 2nd stage thermostat adjustment (where fitted)
8. 3rd stage thermostat adjustment (where fitted)
9. Limit thermostat manual reset
10. 3 Amp control circuit fuse
11. 6.3 Amp burner control circuit fuse
12. Space for optional burner hours run meter
13. Boiler flow temperature thermometer
14. Space for optional burner modulation controller
9 10 11 12 14
2
3
4
5
IMPORTANT -
A single phase 230V supply is required for the control panel operation. Single phase burners are
electrically supplied via the control panel. Three phase burners require a separate three phase
isolated supply (by the installer) direct to the burner, incorporating a flexible connection to allow for
boiler/burner door opening. In this case control cables fitted with wieland plug/sockets will still run
between the control panel and the burner. All power supplies to the boiler/burner/other associated
equipment (ie: gas booster, separate oil pump, etc.) should be isolated via the same switched isolator.
!
August 2014
