Pressure Relief Discharge; Pressure Relief Pipe Work; Alternative Prv Connections - Combined Prv/Condensate - Bosch Worcester 2000 Series Installation And Maintenance Instructions Manual

Pre-Installation
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).
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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.
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• 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,
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Fig. 36 Pressure relief pipe work
0010026770-001
[1]
[2]
[3]
[4]
4.6.2
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.
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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2
3
3
4
4
Discharge pipe (turned back onto external wall example)
Outside wall
Discharge pipe (into drain or gully example)
External drain

Alternative PRV connections - Combined PRV/condensate

Worcester 2000 – 6 721 814 551 (2019/09)
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