Pre-Installation
Worcester 2000 – 6 721 814 551 (2019/09)
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Minimum Standard
▶ The following guidance indicates the minimum standards that must
be maintained for the Installation and Maintenance of a product.
Appliances with condensate pump, CondenseSure accessory or
have trace heating fitted.
The need to insulate the pipe work through the wall is not normally
required for appliances with a condensate pump or CondenseSure/
trace heating fitted for external runs under three metres.
Trace heating fitted:
• Check with trace heating manufactures instructions for additional
requirements.
Condensate pump or CondenseSure fitted to the appliance:
• External pipe work exceeding three metres in length or installation
with increased risk of freezing due to environmental factors:
– Additional protection of insulating the entire run of external pipe
work [5] should be carried out, with a recess in the external face
allowing better insulation protection coverage [4] as it transitions
to the outside of the building.
– The hole through the wall must be sealed to the building fabric on
the internal [1] and external [3] face using a suitable building
material, (use a 40mm sleeve [2] to pass the condensate
discharge through and then seal the internal and external faces).
Fig. 35 Additional protection for transition through wall
[1] Internal face sealed (32mm pipe sealed to sleeve)
[2] 40mm sleeve
[3] External face sealed (32mm pipe sealed to sleeve)
[4] Insulation recessed into the wall
[5] Condensate discharge pipe
4.6 Pressure relief discharge
4.6.1 Pressure relief pipe work
CAUTION:
Scalding risk from hot water or steam!
▶ The pressure relief valve (PRV) is an appliance safety device and may
discharge hot water or steam when activated.
▶ The outlet pipe should be sited in such a way that it does not cause a
hazard or an obstruction when discharging, for example above a
window, entrance door or other public access way.
• The pressure relief discharge pipe [1 or 3] should be run in at least
15mm diameter copper pipe or pipe made of a material that will
withstand PRV discharge temperatures and pressures and which
complies with BS 5254 or BS EN 1451.
• Plastic pipe work must be properly supported with a maximum of
300mm between supports to prevent sagging and run downwards
away from the appliance.
• The pressure relief should discharge away from any electrical or other
hazard, preferably to an external drain or soak-away.
• The pipe [1 or 3] should be finished with a partial bend, near the
outlet to face the external wall (as shown) to help prevent freezing.
• 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.
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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