5
IMAX XTRA EL
-
Installation & Servicing
GENERAL
FLUE INSTALLATION
IMPORTANT.
It is the responsibility of the installer to ensure,
in practice, that products of combustion discharging from the
terminal cannot re-enter the building or any other adjacent
building through ventilators, windows, doors, other sources of
natural air infiltration, or forced ventilation / air conditioning.
If this should occur the appliance MUST be isolated from the gas
supply and labelled as 'unsafe' until corrective action can be taken.
Terminal Position
Due to the high efficiency of the boilers pluming will occur.
Vertical termination is recommended and terminal positions which
could cause problems should be avoided. Particular care should
be taken in the case of large output boiler installations, and
complying with the requirements of the Clean Air Act.
The flue must be installed in accordance with the appropriate
Building Regulations and standards listed on page 4 and in
compliance with BS6644. In IE refer to I.S.820:2000.
FLUE SYSTEM DESIGN
Due to the high efficiency of these boilers, the flue gas
temperatures are low and the buoyancy in the stack will be
relatively small. The boiler is supplied with an integral fan which
is fully matched to the boiler in each case to provide correct
combustion air flow and overcome the flue resistance.
The power of this fan is such that there is a large reserve of
pressure available to overcome a significant length of flue without
affecting the combustion performance of the boiler. The maximum
& minumum pressure available measured at the base of the flue
to overcome combined flue and air resistance is 100Pa (max) and
-10Pa (min) for all model sizes. The pressure should be checked
at maximum heat input to ensure this maximum pressure is not
exceeded. Care should be taken with tall flue systems to ensure
excess buoyancy is not created. A negative pressure must not be
created at the boiler flue outlet.
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Boiler Size
320
395
470
545
620
Flue Pressure (max) Pa
100
Flue Pressure (min) Pa
-10
The addition of elbows and their positions in the flue and the
terminal will have a significant effect on the maximum flue length.
Consult with your flue supplier for detailed design work.
IMPORTANT NOTE.
If combustion air is drawn from within the boiler room, ensure
no dust or airborne debris can be ingested into the appliance.
Dusty concrete flooring should be sealed to reduce the
presence of dust. Ideally where possible duct the air supply
into the boiler room from a clean source outside the boiler
room/building.
If the air filter accessory is fitted the 100Pa / -10Pa pressure requirement
must be checked at maximum heat input with the filter fitted.
Material
With no requirement for buoyancy to discharge flue products
and with low flue gas temperatures, single wall flues are suitable
for most installations. Care should still be taken to maintain
compliance with building regulations and relevant standards.
Care should also be taken in the selection of flue terminals as
these tend to accentuate the formation of a plume and could freeze
in cold weather conditions.
Care should be taken to ensure the specification of the chimney
is suitable for the application by reference to the manufacturer's
literature.
WATER CIRCULATION SYSTEM
The boiler is suitable for connection to a sealed heating system or an
open vented system.
A circulation pump MUST be connected to the boiler, see below.
The boiler must NOT be used for direct hot water supply. The hot
water storage cylinder MUST be of the indirect type.
Single feed, indirect cylinders are not recommended and MUST
NOT be used on sealed systems.
The appliances are NOT suitable for gravity central heating nor are
they suitable for the provision of gravity domestic hot water.
The hot water cylinder and ancillary pipework, not forming part of
the useful heating surface, should be lagged to prevent heat loss
and any possible freezing - particularly where pipes run through
roof spaces and ventilated underfloor spaces.
The boiler must be vented. There must be no low points between
the boiler flow connection and a system vent point, which should be
positioned as close as practically possible to the boiler flow connection.
Draining taps MUST be located in accessible positions, which
permit the draining of the whole system - including the boiler
and hot water storage vessel. They should be at least 1/2" BSP
nominal size and be in accordance with BS. 2879. Do not use the
boiler drain tap to drain the system as this can induce sludge into
the heat exchanger.
The central heating system should be in accordance with the
relevant standards listed on page 4.
Once the burner has extinguished the boiler requires a 2 minute
pump overrun to dissipate the residual heat. In order to allow this
a 2 minute pump overrun is incorporated into the boiler control.
An external pump must be connected or controlled by the boiler,
however if it is directly connected it must not exceed 1.3A inductive
load, if it does then a relay or contactor must be used.
Flue Products/Flue Pressure
Sampling
Point
