Modern temperature control plays an important
part in comfort and energy saving. We explain the fundamentals and
IPPEC's equipment available for your new home.
Most people now understand
the importance of good insulation in a modern home and tougher standard
of insulation is required next year. High efficiency condensing
boilers in conjunction with underfloor or radiator heating systems
are becoming the norm. But what about temperature control? Government
figures claim that as much as 5% energy is saved per degree of temperature
reduction, yet most heating systems are still using a simple time
clock (euphemistically called 'programmer') situated near or at
the boiler, with one room thermostat in the entrance hall. The only
other temperature controller widely used is the thermostatic radiator
By the time the one room
thermostat is satisfied, the rest of the house could be either too
hot, too cold or too uncomfortable. In other words there is little
control over the heat output in the house. Such a simple system
cannot adjust for changes in outside temperature or respond quickly
to any other factors, such as crowded rooms, solar gain, or busy
I connects two programmable thermostast, two individual thermostast,
cylinder high limit and adjustable thermostast to boiler, valves
traditional so-called programmers provide one further function,
and that is timing the hot water cylinder. The temperature at the
cylinder is set by a thermostat located somewhere approximately
at one third the cylinder height. Again the programmer does not
provide any water temperature control or influence the relation
between hot water and space heating.
A contemporary house needs
up-to-date controls which can modulate the heat input according
to outside temperature, usage of rooms and other heat sources such
as fireplaces, solar warming. The control system should be able
to cope with more than one heat source within the building. A well
insulated home requires more energy to meet demand for hot water
than for space heating. Trying to heat both at the same time is
uneconomical. Too a large a boiler is avoided by allowing the boiler
to divert its heat from space heating to hot water heating when
the cylinder calls for heat. This is known as hot water priority
Area zone control and
individual room control
Air temperature control is
useful where rooms need to have different temperature settings for
different times. In other words, they act as high limit thermostats
for the area in question. As an example the first floor area of
a house needs to be heated for a few hours in the morning and evening
and usually at a lower temperature than the ground floor area. This
requirement can be easily and economically met with a standard programmable
thermostat. These are battery operated and need only two wires to
connect them. They have multiple day and week settings of high and
low temperatures requirements. Say 20 0C. during the day and 16
0C. at night. The prog. ‘stat (as it is known in the industry) controls
a motorised valve, pump or actuator at the manifold. Individual
room control is popular with underfloor heating and again thermostats
or programmable thermostats are used in these systems to control
a thermal actuator at each circuit for the underfloor manifold.
Each room is a circuit.
Two years ago regulation was introduced to have more than one heating
zone control in a house. This legislation has been widely ignored
for the simple reason that wiring more than one heat zone has become
more complex for the average plumber or electrician to handle. The
installer is required to wire at least 5 wires correctly to each
motorised valve and to the rest of the heating system. This is because
the valve act as a relay and the micro or end switch turns on the
boiler or pump. Without this end switch any thermostat coming on
will turn on all the heating zones at the same time irrespective
whether other thermostat are calling for heat or not. Recognising
the problem, IPPEC introduced fully fledged wiring centres. These
are not just junction boxes where all the connections are made.
They include relays, timers and LED display in the case of IPPEC’s
aptly named Multizoner. The connected thermostat operate only the
required zone and also makes sure the boiler if fired and the heating
pump is running. The connections are labelled on the circuit board
or connect only in one way. So that error is reduced and any competent
person can wire a multiple zone heating system.
Controlling underfloor heating
Much has been written about the benefit of underfloor heating in
a modern house. But little has been said about its temperature control.
Heating a large mass of floor by few degrees can take longer than
heating a small amount of water in a radiator. Add to that the ‘hot
water bottle effect’ of a radiator (that is touch a hot rad. and
you feel good even though the room is still freezing) and you can
see why people demand individual room control with underfloor heating.
Manufacturers oblige by supplying room thermostat programmable or
otherwise and Electro-thermal actuators that clip to the corresponding
port on the manifold. A wiring centre greatly simplifies the wiring
of these heating circuits actuators to the thermostats and boiler.
Actuators and motorised valves are available in 230 and 24 volts.
IPPEC Multizoner is available in both voltage while Honeywell is
available only in 24 volts. Needless to say, wiring centres and
programmable thermostats can be used to control radiators or underfloor
heating or a combination of both. They are used for new houses,
refurbishment or even extensions.
Hot Water Control
The wiring centres also control the motorised valve to the cylinder
as is done with the existing programmers. Here the cylinder two
port valve is opened and the boiler is fired whenever the cylinder
thermostat calls for heat (the ‘S plan’). Otherwise a three port
divertor valve is switched over to hot water by the wiring centre
(the ‘Y plan’). There is no need for the end switch connection as
the relay in the wiring centre turns on the boiler and or pump.
IPPEC’s Multizoner I has extra features such as built-in 2 channel
clock to control the timing of the hot water cylinder or towel rail
circuit, and the bronze secondary circulation pump.
we shall discuss the merits of weather compensation in well insulated
area zones programmable thermostat wired through the Multizoner
wiring centre solves central heating wiring problems.