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WD420/3/2007
Chapter 3 - Boiler Location
BS 1363. There must be only one common method of isolation for the boiler and
its control system.
The appliance must be connected to the 3A supply via a fused double-pole switch
having at least 3 mm (1/8 inch) contact separation in both poles, serving only the
boiler and the system controls.
The connection point to the mains supply should be readily accessible and
adjacent to the boiler, except for rooms containing a bath or a shower. Refer to
section 3.3 Position.
3.4.2
External Wiring & Controls
1.
2.
3.4.2.1 Enhanced Control Options
The Qudos 28s can be wired into a conventional heating installation using only
permanent and switched live connections.
However, the Qudos 28s features a wide range of OPTIONAL control features
normally associated with commercial boilers installations at additional cost. These
are provided as standard in the Qudos 28s and require low costs sensors to be
added to activate them. The features provided are detailed below. Refer to
Chapter 4.8 for further wiring detail.
Installation & Servicing Instructions
The boiler is designed so that all control wiring is external to the boiler.
Heating control signal inputs must be 230VAC "switched live" type unless
using a Keston Room Controller (see below) or 0-10VDC input.
Room Compensation (Opentherm)
A Keston Room Controller may be used to provide room compensated
control to ensure the boiler output is matched to the rooms requirements
at optimum boiler efficiency. This is only recommended for heating only
applications
Weather Compensation (Ext Sensor)
A Keston outside temperature sensor may be connected as an option.
The boiler will automatically detect this connection and will operate on a
"weather compensation" basis when receiving a heating demand signal
from the SL terminal or from a Keston Room Controller. Screened cable
(80% density) must be used to connect the outside temperature sensor.
Solar Control
Where a solar thermal system is in use, with a twin coil cylinder such as
the Kesotn SpaTwin, the Qudos 28s will control operation of the solar
pump in conjunction with the boiler. The boiler requires connection to the
solar tank sensor, solar panel sensor and solar pump
Modulating DHW Reheat
The Qudos 28s can provide direct modulation to maximise the re-heat
performance of the DHW cylinder. A DHW cylinder sensor can be
connected directly to the Qudos 28. A DHW demand input can also be
provided to control DHW reheat activity, perhaps in conjunction with Solar
Thermal. With this facility connected an automatic anti-legionnella facility
can also be provided.
Analog Demand (0-10VDC)
Where external control panels are used, in boiler room applications, a
0-10VDC input can be connected to the boiler, in place of the SL1
switched live demand. The 0-10VDC signal will drive the first setpoint at
1VDC = 10C setpoint (NB: <0.5VDC is off, >8.0 VDC is 80C)
External Lockout Signal
Where remote monitoring and/or alarms are installed the boiler offers a
volt-free lockout signal output. The boiler will provide a closed circuit
across the two output points when the boiler is in lockout.
The Keston Qudos 28s & Qudos 28sP Boilers
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