Air Supply; Compartment Installation; Condensate Drainage; Radiant Floor Heating - Keston 50 - GC Installation And Servicing Instructions

WD50/2/1997
A minimum clearance of at least 350 mm must be left between the terminations.
2.8.7 General Installations
All parts of the system must be constructed in accordance with BS 5440 Part 1,
except where specifically mentioned in these instructions.
All pipework must be adequately supported.
All joints other than push-on or plastic compression connectors must be made
and sealed with solvent cement suitable for muPVC pipes and conforming to BS
6209: 1982.
External wall faces and any internal faces of cavity walls must be made good.
2.9

AIR SUPPLY

The Keston is a room sealed appliance and therefore does not require purpose provided
ventilation for combustion air.
2.10

COMPARTMENT INSTALLATION

Where the appliance is installed in a cupboard or compartment, no air vents are
required. The boiler will run sufficiently cool without ventilation.
2.11

CONDENSATE DRAINAGE

Being a condensing boiler, the Keston is fitted with a condensate trap at the base of the
heat exchanger and flue assembly, with facility to connect to a drain point underneath the
appliance.
Use only plastic piping and do not reduce below 22mm internal diameter within the
dwelling. Condensate should preferably be drained into the house sanitary waste system
or, alternatively, the rainwater system. Termination of the pipe must be either at a branch
or stack internal to the house, or externally at an open gully. Alternatively, discharge into
a purpose made condensate soakaway can be considered. Existing or purpose built
drains must use suitable corrosion resistant material as condensate is mildly acidic.
A minimum slope downwards towards the drain of 2.5
Freezing of the termination and pipework must be prevented. Any drainage pipes outside
the house must be at least 32 mm inside diameter.
Further guidance is given in the British Gas Publication 'Guidance Notes for the
Installation of Domestic Gas Condensing Boilers'.
2.12

RADIANT FLOOR HEATING

This type of heat distribution creates an exceptionally evenly heated environment and
since it is hidden beneath the finished flooring does not interfere with furniture
placement. The homeowner has complete freedom to decorate without having to
contend with any heating equipment visible in the homes interior. The low operating
temperatures of this type of system lead to very good operating efficiencies. In fact,
under floor heating can produce in excess of 95% operating efficiency from a Keston
condensing boiler. Water temperatures in radiant floor heating systems must be kept
relatively low, generally under 48
to the touch. If radiant heating is only one application for a multi-zone system which also
requires higher delivery water temperatures for other zones (i.e. water heating, skirting
heaters etc.) then the radiant floor zone temperature will need to be controlled separately
from the boiler.
If radiant floor heating is the only application of the boiler, the boilers temperature limits
can be lowered accordingly by introducing an external thermostat control mounted on the
return pipework into the boiler. This thermostat can then be used to interrupt power
Installation & Servicing Instructions
Chapter 2 - Boiler Connections
o C, so that surfaces do not become uncomfortably warm
Page : 16
The Keston 50, 60 & 80 Condensing Boilers
o
(45mm fall in 1m) is essential.