1. Heating Components
The following slide shows all the components of a fully
pumped central heating and hot water system using two
zone valves
Click on any component to find out further information
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commentary
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3. Radiators
Most manufacturers
recommend that radiators
are fitted beneath a window.
Curtains should finish
100mm above the radiator
Despite the name ‘radiator’, about 85 per cent of
the heat is given off by convection. The heat output
of a standard panel radiator can be further
improved by the addition of fins welded onto the
back.
4. •Dual diaphragm temperature sensing element
ROOM THERMOSTAT
•Suitable for surface or switch box mounting
•Heat anticipator for close temperature control
•10 to 30°C setpoint range
•Change-over contact switching (cooling loads)
•Double insulated
The thermostat should be
fitted 1.5 metres from the
floor
5. Combination boilers Boilers
This type of boiler is designed to
heat up a cold-water supply
instantaneously for domestic hot
water
SEDBUK rating – a measure of the
seasonal efficiency of a boiler
installed in the UK
System boilers supply
domestic hot water
indirectly. The key controls
are all built-in to the boiler Condensing boilers are
unit, including the expansion approximately 94% efficient
vessel, the pump, and the
bypass.
6. •Large backlit display Timers and Programmers
•Factory set clock and date
•Extra hour facility
•Fits on standard back plate
•Up to 3 on/off times per day
Heating and hot water programmes
can be independently controlled to
allow the system to be operated
efficiently.
7. Pumps should be fitted in a position
Pumps that ensures that most of the
system is under a positive pressure
the connection point of the cold
feed in the system is the point at
which the pressure in the system
changes from positive to negative.
This is called the neutral point.
8. Cylinders
Cylinders are usually
supplied factory insulated
The amount of water stored
should relate to the likely
consumption and recovery
rate
To prevent one pipe circulation, the hot water
distribution pipe should be run horizontally, by a
minimum of 450mm, after leaving the cylinder.
9. Two port valve
Two of these are included on a standard fully pumped system, one
controlling heating and one hot water. These valves are really
what brings the key circuits together to get the system to
function fully.
Rr
Rr
10. Cylinder Thermostat
With the Honeywell thermostat no earth
or neutral connection is required.
The thermostat should
be fitted one third of
the way up from the
cylinder base
There is a live in connection via the wiring centre from
the ‘on’ switch connection for hot water to the 1
terminal in the cylinder thermostat. There is a live out
connection from the C terminal which connects to the
hot-water motorised valve.
11. Bypass
These are mechanical devices used to
make sure water can flow through the
boiler to maintain a minimum water-flow
rate should a system using zone valves or
TRVs become closed. Once set, the valve
opens automatically as the TRVs or zone
valves close and the system pressure goes
over the pre-set limit.
Use of the bypass valve reduces system noise
and increases pump life by preventing it working
against a ‘dead head’.
