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The British Flue and Chimney Manufacturers
Association website,
www.bfcma.co.uk,
produces an
authoritative and informative download about flues
for stoves.
The Chimney Terminal
The existing chimney pot or terminal must be suitable
for stove installation and should not restrict the smoke
and fumes from the stove. It must provide at least the
same outlet area as the flue pipe. It may be that your
existing chimney terminal has been replaced with a
ventilating terminal if the fireplace has been closed off
at some point and this will need replacing.
Your installer will be able to advise you on the correct
specification of any new cowl or terminal. Cowls have
the additional advantage of limiting rain entering the
flue system which could cause the inside of the stove
to rust when it is not being used, particularly during
the long periods outside the heating season.
Important: If you are not using a chimney liner
you must provide a means of inspecting the flue
system and the top of the stove.
SYSTEM INSTALLATION:
GENERAL GUIDELINES
Central heating systems
A pumped central heating circuit combined with a
gravity hot water circuit is generally the accepted
specification for multi fuel boiler systems which are
not linked to another system. However, achieving
the correct balance between the pumped and gravity
flows in such a system is critical to the efficient
performance of the boiler stove and should be left
to an experienced Hetas wet installer or appropriate
specialist registered on a Competent Persons scheme.
Increasingly new systems are specified as ‘fully
pumped’ to provide improved operational control and
this is a feature that we would recommend for your
system.
Dual fuel linked systems
You may have purchased your new Precision Inset
Boiler stove with the intention of adding it to an
existing heating system powered by a different fuel
type. This is likely to be to a non-pressurised oil or gas
system, but could also be solar powered, probably in a
new pressurised system.
Linking two such systems requires specialist
knowledge to ensure a fully functioning system which
is efficient, safe and legal. Such systems require the
installer to possess a knowledge and understanding
which will be beyond the provisions and intentions of
these general installation and operating guidelines.
The United Kingdom’s Solid Fuel Association
through their website
www.solidfuel.co.uk
, provides
informative downloads on various link-up system
solutions.
The most common problem with link up systems is
a failure to understand the existing system which
may have faults which are then exacerbated by the
new link. Our advice when linking this boiler stove
to any system is therefore to consult the appropriate
installation expert who will develop an understanding
of your requirements and provide you with a
thorough survey of any existing system.
There are various Government competent persons
schemes listing installers trained in designing and
installing linked systems:
• Hetas
www.hetas.co.uk
• Association of Plumbing & Heating Contractors
(Certification)
www.aphc.co.uk
• Building Engineering Services Accreditation
www.besca.org.uk
• NICEIC www.niceic.org.uk
BASIC SYSTEM ESSENTIALS
The basic system diagram on the opposite page
should be used for general guidance purposes only
and is included here to demonstrate basic system
principles. Combined with the at-a-glance list below
this should provide you with a basic understanding of
the essential requirements your system should have.
As each system and its requirements will vary the list
below is by no means meant to be comprehensive.
A good system should adhere to the following:
• Adjustable flow circulating pump
• High and low limit thermostats
• Cold feed pipework must be minimum 22mm dia’
• Open vent pipework must be minimum 22mm dia’
• Overflow pipe must be 22mm dia’ copper
• All pipework must be able to operate at
above 100ºC
• Feed / expansion tank must be galvanised steel
or copper
• Float valve should also be copper
• No automatic or manual valves on cold feed
or open vent pipework
• Heat leak radiator fitted to gravity circuit
• Exposed pipework (eg lofts) must be insulated
to prevent freezing
• Hot water cylinder and thermostat
• System should be capable of being completely
drained
Heat leak radiator
A heat leak radiator with a minimum rating of 10%
of the boiler’s total output to water should be fitted
to the gravity circuit. Heat leak radiators rated at
approximately 2kW (6,800BTU) tend to be the norm
in most systems. Pipes to and from the heat leak
