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.

The Problem
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 valve.
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 kitchen.

The Multizoner I connects two programmable thermostast, two individual thermostast, cylinder high limit and adjustable thermostast to boiler, valves and pumps.

The 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 heating.

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.

Multizoner wiring centres
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.
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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.

Domestic 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.

Next month we shall discuss the merits of weather compensation in well insulated homes.
Multi area zones programmable thermostat wired through the Multizoner wiring centre solves central heating wiring problems.