General - gledhill TORRENT DIRECT Design, Installation & Servicing Instructions

3.1

GENERAL

(a) A typical arrangement of the hot and cold water system is shown in figure 3.1. All Torrent
models are designed to be fed directly from the mains and they fulfil the requirements of
Water Bylaw 91, and therefore do not require a check valve to be fitted to the cold water
supply pipe.
(b) The performance of the Torrent is directly related to the cold water supply pressure and
volume to the dwelling. This must be capable of providing for all those services which
could be required simultaneously and the maximum demand should be calculated for
sizing the distribution network.
As a general guideline, although a 15mm external service may be sufficient for the
smaller dwelling with one bathroom, a 22mm service is preferred (25mm MDPE) and
should be the minimum for larger dwellings.
(c) The Torrent will operate at dynamic pressure as low as 1.5 bar (at the appliance) which
must be available when the local demand is at its maximum, but the preferred range is
between 2 and 3.5 bar.
If the incoming static mains pressure exceeds 3.5bar at any point in the 24 hour cycle,
then a pressure limiting valve set at 3.0 bar should be fitted downstream of the stop tap
where the cold supply enters the dwelling.
(d) If a water meter is fitted in the service pipe, it should have nominal rating to match the
anticipated maximum simultaneous hot and coldwater demand, calculated in accordance
with BS 6700. This could be up to 50 l/min in some properties.
(e) The equipment used in the system should be suitable for a working pressure of 10 bar and
the units must be fitted strictly in accordance with the requirements of the Local Water
Undertaking and the relevant Water Bylaws.
3.2 USE IN HARD WATER AREAS AND SCALE PROTECTION
The patented design of the domestic hot water heat exchanger is such that the turbulence
through the coil slows down the formation of the scale in moderate hard water conditions.
However, the requirements set out in the 'Domestic Heating Compliance Guide' and the Building
Regulations approved documents L1A and L1B regarding scale protection should be complied
with.
These requirements state that; "where the mains water hardness exceeds 200ppm provision
should be made to treat the feed water to the water heaters and the hot water circuit of
combination boilers to reduce rate of accumulation of scale". To comply with this requirement: -
(a) The hardness of the mains water should be checked by the installer and if necessary
suitable in-line scale inhibitor device should specified for hardness levels between 200
and 300ppm (mg/l).
(b) Where the hardness level is 300ppm (mg/l) and above, the optional phosphate type
inhibitor should be specified and fitted at a suitable point in the cold water supply to the
appliance.
It is important that where the supply to the Torrent is in 22mm the in-line scale inhibitor is
also 22mm. In practice servicing is not normally required but in hard water areas, the
requirements can be considered similar to those needed for instantaneous or 'combi'
appliances.
The installation of scale inhibitor should be in accordance with the manufacturers
instructions and Water Byelaws.
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DESIGN