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WD420/3/2007
Chapter 2 : General Instruction
2.1
DESCRIPTION
The KESTON Qudos 28s and Qudos 28sP boilers utilize the latest in condensing
technology to produce a high efficiency boiler with SEDBUK A rated efficiency plus
advance controls to maximize operational efficiency.
The Qudos 28s is unique in concept and design. It comprises a high efficiency stainless
steel heat exchanger coupled with a low emissions burner to deliver ultra high efficiency
condensing mode operation within a compact wall hung cabinet. The unit automatically
adjusts gas and air rate according to demand to give a heating input in the range of 7.8kW
to 29.4kW (GCV). The integral pump assembly, in the Qudos 28s, is automatically speed
controlled to best match water flow rate to heat output & further increase appliance
efficiency.
The Qudos 28s has been developed to embrace the concept of advanced controls to
ensure the ultra high performance burner and heat exchanger system is run to optimum
performance levels whilst provided or exceeding the comfort levels demanded. As a result
the boilers feature a host of additional connections for:
-
an optional outside sensor to enable the boilers inbuilt weather compensation
option which delivers enhanced user comfort levels with peak operating efficiency
due to the lower flow temperatures involved.
-
an optional "Opentherm" connection point for the Keston Room Control module
which provides further advanced user control for room temperature compensation
and optimum start.
-
optional 0-10VDC input where temperature control is provided by external 3rd
party intelligent controls
-
optional connection of a DHW thermistor to enable modulated reheat of DHW and
optional legionella prevention function
Further, the Qudos 28s is developed with the concept that the gas boiler in the modern
home is often supplemented by alternative or renewable energy sources. As a result the
Qudos 28s features:
-
optional connection of a solar thermal system, pump, panel and DHW sensor, for
direct control of solar thermal system from the boiler. Other additional energy
source systems, such as Ground Source Heat Pump, will be accommodated
soon.
The boilers have the added advantage of very high efficiency, and small diameter muPVC
plastic flue which can be extended up to 20 metres horizontally or vertically. The boilers
also feature an optional remove fascia panel so the boiler can be controlled from within
the house where the boiler is located outside the house or in the loft.
The Keston Qudos 28s uses a variable speed combustion blower to deliver a premix of
gas and air to a downward firing burner in a high efficiency, single pass heat exchanger.
The flue system is room sealed and fan powered. The ignition is direct spark and fully
automatic. The boiler housing is not waterproof and should be installed in a position
where it will always be dry. Combustion air is drawn from the cabinet which is connected
to outside atmosphere via a small diameter plastic intake pipe. The cabinet therefore
remains under negative pressure at all times the boiler is operating.
These boilers are designed for use as part of a sealed water central heating system with
fully pumped circulation. The pump, an 8l expansion vessel and associated safety devices
are all fitted within the Qudos 28s boiler. However, consideration should be given to
additional expansion vessels on larger systems where 8 litres may be inadequate.
Installation & Servicing Instructions
The Keston Qudos 28s & Qudos 28sP Boilers
2. GENERAL INSTRUCTION
Page : 4
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