Flow and return pipework between cooker and zone
valves must be 28mm diameter minimum.
Space and water heating should be in accordance with
the relevant recommendations of BS 5410: Part 1.
In a combined central heating and domestic hot water
system, the hot water storage vessel must be of the
indirect cylinder type to BS 1566: Part 1. The hot water
storage vessel should be insulated with not less than
75mm thick mineral fibre or its equivalent.
Cisterns and pipework should not be situated in areas
which maybe exposed by freezing conditions.
Draining taps must be located in accessible positions
which permit the draining of the whole system, including
the heat storage vessel. Draining taps should be at least
1
/
2
in BSP nominal size and be in accordance with BS
2879.
The appliance boiler section should be connected to a
cistern water supply, subject to a maximum head of
18.25m.
Alternatively a ‘sealed’ system may be used with an
appropriately sized expansion vessel and the pressure
relief valve is limited to 2 bar, See Page 27.
The heating system must be designed (and adjusted if
necessary) to give temperature differential across the
boiler at full output of 10-14°C. When horizontal runs are
used the pipes should rise upwards in the direction away
from the appliance.
Circulating Pump
It is recommended that the selected pump be sized to suit
the boiler pressure loss and therefore adequate to give
the required temperature differential between the flow and
return.
The pump should be able to meet the requirements of the
system design and fitted in a readily accessible position.
Isolating Valves
Isolating valves (preferably of the keyless type) must be
fitted to the inlet and outlet of the circulating pump to
facilitate service and replacement of pump without
draining the system.
Inhibitor
A corrosion inhibitor
MUST
be added to the heating
system to protect the heat exchanger and pipework.
Inhibitor must also be replaced if the system is drained
after installation. As a precaution the heating system
MUST
also be flushed out prior to the addition of the
inhibitor to ensure any flux, debris is removed.
Independent temperature controls with time switch control
are recommended for providing temperature comfort from
radiators.
Typical controls can be motorised valves operated by
room thermostat and cylinder thermostat.
Thermostatic radiator valves may be fitted when required.
The boiler should be controlled so that it operates on
demand only.
Operation of the system under control of the boiler
thermostat only, does not produce the best efficiency.
Refer to the control equipment manufacturers literature
for information e.g. wiring.
Site requirements
14
WATER CIRCULATION SYSTEM
HEATING CONTROLS
