2. GENERAL INSTRUCTION
2.1 DESCRIPTION
The KESTON Qudos 28h and Qudos 28hP boilers utilise the latest in condensing
technology to produce a high efficiency boilers with SEDBUK A rated efficiency plus
advance controls to maximise operational efficiency.
The Qudos 28h 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 Qudos 28h 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 28h 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 28h 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 Keston Qudos 28h 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 or open vented water central
heating system with fully pumped circulation.
The boiler heat exchanger is made from highly corrosion resistant stainless steel in
corrugated pipe form which provides massive surface area within a compact dimension.
The hot combustion gases from the down firing burner pass around the stainless steel
pipes imparting heat into the system water. The Qudos 28h is not a high water content
boiler and does not contain the metal mass, or water volume, of a cast iron or steel boiler.
This boiler is of low mass and low water content and therefore responds faster when there
is a call for heat. The Qudos 28h features full user diagnostics, integral frost protection
WD440/3/2007 Chapter 2 : General Instruction The Keston Qudos 28h & Qudos 28hP Boilers
Installation & Servicing Instructions Page : 4
