Alternative Prv Connections - Combined Prv; Condensate; Cleaning Primary Systems - Worcester GR8700iW 35 C Installation And Maintenance Instructions Manual

Pre-Installation
• In all normal circumstances a PRV discharge pipe installation as
described above is suffice to meet all but the most exceptional
circumstances.
– Where the PRV discharge pipe could be susceptible to damage,
vandalism, freezing etc that could cause either a blockage or
restriction in the ability to discharge safely then a tundish should
be considered. The tundish should be sited in a position where
damage to the property or occupants cannot occur from any
spillage or discharge.
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Fig. 36 Pressure relief pipe work
[1] Discharge pipe (turned back onto external wall example)
[2] Outside wall
[3] Discharge pipe (into drain or gully example)
[4] External drain
4.6.2 Alternative PRV connections - Combined PRV/condensate
The PRV or a combined PRV/ condensate discharge can be connected
into a suitable internal waste system, the installer must ensure that all
the pipe work, including the waste pipe, is capable of withstanding PRV
temperatures and pressures.
Connection to a waste water pipe is possible by using either:
• A shielded tundish with non-return valve can be used to discharge
upstream of a trap (there must not be a trap directly in the PRV
discharge pipe without a tundish.
• A PRV can discharge directly into a suitable waste pipe downstream
of a trap. Connections must be on top of the pipe to ensure they do
not block. A Hotun (or similar) can be fitted for visual indication if
desired but is not necessary.
The guidance of BS 6798 sections 6.3.5 and 6.4.3.2a must be followed.
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4.7

Cleaning primary systems

NOTICE:
Risk of damage to system or appliance!
Debris from the system can damage the appliance and reduce efficiency.
Failure to comply with the guidelines for the use of water treatment with
the appliance will invalidate the appliance guarantee and contravene the
Building Regulations.
▶ It is a requirement of the Building Services Compliance Guide which
is a second tier document to the Building Regulations to flush and
inhibit the primary water system in accordance with BS 7593.
▶ The Building Services Compliance Guide recommends that a primary
water cleanser is fitted to the system.
▶ Worcester Bosch recommend fitting a filter that will help remove both
magnetite and non-magnetic debris.
Worcester offers two filters that helps remove both magnetite and
non-magnetic debris; 22mm version, part number 7 733 600 236
and a 28mm version, part number 7 733 600 237.
NOTICE:
Risk of damage to system or appliance!
Artificially softened water must not be used to fill the central heating
system.
▶ Salt based, artificially softened water MUST NOT be used to fill the
system
NOTICE:
Sealing agents
Normally the addition of sealing agents to the system water is not
permitted as this can cause problems with deposits left in the heat
exchanger.
▶ Heating systems may lose small amounts of water over time. In cases
where all attempts to find a system micro leak have failed, Worcester,
Bosch Group supports the use of Fernox F4 leak sealer.
Before cleaning the system:
▶ Ensure that the system and pipe work is in good working order.
▶ Where possible keep the existing appliance/circulating pump in
place when flushing the system before installing the new
appliance. Alternatively use an after market power flushing
system or similar to remove magnetite and other debris from the
central heating system.
– Even new central heating systems contain contaminants that
need to be removed before treating the system with inhibitor/anti-
freeze.
– When an appliance is installed onto a new system then it is
possible to use the appliance whilst cleaning the system. A system
filter must be fitted to the return to reduce the risk of
contaminants entering the appliance.
▶ Follow the guidance of BS7593.
Inhibitor
Add a suitable inhibitor or combined inhibitor/anti-freeze, if the system
is exposed to freezing conditions, to the heating system in accordance
with the DWTA code of practice and manufacturer's guidelines.
Products approved to the BuildCert standard are deemed as compatible
with the components and equipment within the appliance and system.
Greenstar 8000 Style – 6720883864 (2019/02)