Page 509 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 7 Central heating systems

In most instances, zoning requires the separating of the upstairs circuit from the
downstairs or, in the case of single-storey dwellings, separating the living space
from the rest of the property. Separate time and temperature control of the
individual circuits is a necessity.

Zoning with separate temperature control
Separate temperature-controlled zones provides a much better living
environment because different parts of the dwelling can be maintained
at different temperatures without relying on a single room to dictate the
temperature across the whole system. Lower temperatures can be maintained
in those rooms within the dwelling that are not occupied, allowing the dwelling
to take full advantage of any solar gains, especially in rooms that face south,
south-east or south-west. This can be quite pronounced, even in the winter sun.
Significant savings on both energy usage and fuel costs can be made by simply
taking advantage of the free heat that the Sun can provide. Outside sensors
linked to weather compensators, and delayed start and optimum start controls,
further help to reduce energy usage and cost.

Zoning with separate time control
Zoning with separate time control offers another dimension to the concept of
zoning by allowing the heating to be controlled at different times of the day
in different zones. The heat can be focused in those rooms that are occupied
throughout the day, with the heating to other parts of the dwelling timed to
come on in the early morning and evening. Separate zones reduce energy usage
and costs while maintaining improved comfort levels throughout the property.

Zoning in practice

Zoning is required by Approved Document L1A/B of the Building Regulations 2010
and the installer must make decisions on the best way to arrange those zones to
take the best advantage of energy savings while complying with the wishes of the
customer/end user as well as the regulations. The only way this can be achieved is
by talking to the customer and finding out their usage patterns. The main aim of
zoning is to avoid overheating areas that require less heat to maintain the warmth
or because the set point could be lower than in other areas. The point here is that
the number of zones laid down by Document L is the minimum and there are real
benefits to adding additional zones in key areas of the property.
An underfloor system lends itself naturally to zoning as each room is
individually controlled by a room thermostat, which activates actuators on the
individual circuits at the manifold. Further controls can be added where heat
emitters and underfloor heating circuits are installed on the same system. In
this case, the zones are both individually temperature controlled and timed.
The system can also be linked to other advanced controls such as night set-back
and delayed start.

The choice of controls for the zones should be decided by the predicted
activity in those zones. There are many options that can be used individually or
collectively to achieve good system control:

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