Flue System; Air Supply - Keston Qudos 28h User, Installation And Servicing Instructions

WD440/3/2007 Chapter 3 - Boiler Location
capable of meeting the flow rate required at the total pressure loss generated by the boiler
and the rest of the system. The selected pump must comply with BS 1394. It is important
to note that the minimum flow rate must be maintained whenever the boiler is firing.
Systems using zone valves must be specifically designed to only fire the boiler when the
pump is running and the minimum flow rate can be achieved.
3.7.4 Hot Water System (if applicable)
The hot water storage vessel must be of the indirect type (certain direct cylinders can be
used provided they are suitably adapted by fitting an immersion calorifier). DIRECT
CYLINDERS MUST NOT BE USED. Further guidance is provided in BS 1394. It is
advisable to fit a locksheild valve on the cylinder return to enable balancing of the flow rate
through the cylinder.
The Keston qSpa range of stainless steel unvented cylinders are an ideal option for
use with the Keston range. The Keston qSpa range combine exceptional recovery
times with durable, long life stainless steel construction and all associated
controls. Contact Keston Boilers Ltd for information
The Qudos 28h also has advance control options built in which enable modulated reheat
of DHW and anti-legionella function. Refer to Chapter 4 for more detail.
3.7.5 Filling The System (sealed systems only)
The system should be filled using a G24 approved filling loop. The system pressure
should be set to between 1.0 and 2.0 bar.
3.8

FLUE SYSTEM

NB: When
boiler a new flue system must be
used. Do not re-use the existing
boiler flue installation.
3.8.1 Design
Individual air supply and flue outlet pipes are
used. The material used for flue outlet &/or air
inlet must be muPVC to BS 5255 and/or
BSEN1566-1 and BSEN1329 of an internal
diameter of 51 mm. (i.e. nominal 50 mm
diameter muPVC solvent weld waste pipe)
Alternatively, where flue or air intake lengths of up to 60m are require, Keston Composite
75mm flue and air pipe can be used (contact your Keston stockist for details). Keston
Composite 75mm pipe MUST be painted where exposed to UV light.
Both 50mm flue outlet terminal and 50mm air inlet terminal are supplied and are illustrated
in Figure 3.8.1. Both terminals are identical. If 75mm terminals are required these can be
obtained from your Keston Boilers stockist. Request part numbers C.17.2.26.00.0
(terminals) and C.17.2.00.60.0 (50 to 75 adapters).
3.8.2 Maximum Lengths
The maximum lengths of both air inlet pipe and flue outlet pipe, when no bends are used,
are as detailed below.
However, each bend used has an equivalent length that must be deducted from the
maximum straight length stated above. Knuckle bends must not be used.
A 92.5 o sweep elbow is equivalent to 1.0m straight length. A 45
0.5m straight length.
Installation & Servicing Instructions
installing a replacement
The Keston Qudos 28h & Qudos 28hP Boilers
Flue Outlet/Air Inlet Terminals
Figure 3.8.1 : Terminals
o bend is equivalent to
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