Smooth Operating for Underfloor Heating
The energy-saving advantages of underfloor heating (UFH) compared to radiators are clearly understood but there is still scope for improvement in efficiencies if the system is installed in conjunction with modern heat sources such as condensing boilers and heat pumps.
Crucially UFH provides the warmth to a room from the floor up, rather than heating the ceiling space first, and the flow temperature is much reduced. The heat produced by a UFH system is noticeably different to radiators as UFH emits a far greater proportion of its heat as radiant rather than convected heat, giving off a more comfortable form of heat.
Accurately controlling any heating system can improve comfort levels and operational efficiency. With UFH it is common practise to install thermostats in all rooms, enabling temperatures to be set dependent on the requirements of each area, for instance 18°C in bedrooms or 21°C in living areas.
To satisfy the requirements of the Domestic Heating Compliance Guide, heating systems must be fitted with both time and temperature controls.
Exploring the options
Some heat pumps closely match output to the heat loss from a property. While they are able to maintain temperatures, they can struggle with the additional loading required to increase the temperature of a property from cold. Hence some manufacturers promote leaving the system running 24 hours a day at a fixed set point, leaving the thermostats to control the temperature.
Many heating systems operate via a simple on/off basis with the system either being set to desired temperatures or completely off. While this method may be satisfactory for the control of a system with quick response to demand, it is difficult to manage the system with seasonal temperature changes i.e. changing the heat up time as external temperatures change. This can easily lead to either heating up too soon or reaching temperatures later than desired.
Using a night or unoccupied set-back system is an energy efficient improvement over a simple on/off control, and is commonly available as a low cost upgrade with most UFH systems. By controlling the temperature during what would have been an off period to a setting typically 4°C below the normal operating temperature, it is easier to predict the likely heat up time when the system reverts to normal operating temperatures, and energy is not being wasted because it takes less energy to maintain a room at a lower temperature than to heat it from cold.
To provide set-back within the controls, either fully programmable thermostats are used, or a matching time controller is fitted to the system, which signals to the night set-back thermostat the operating mode to work in, thus setting the desired temperature automatically. Where a manifold is covering one area that has similar time demand, such as either the ground or first floor in a domestic house, then a single channel is satisfactory per manifold. In a bungalow one manifold could cover both living and sleeping areas but in these instances it would be beneficial to utilise a two output timer thereby ensuring temperature profiles to suit the occupancy of each area of the property.
It is recommended to check how the communication between timer and thermostats is carried out before installing cables during the electrical first fix as it is commonplace to require an additional conductor in the wiring to carry the set back control signal, so for example 4 core + earth cabling may be required.
To provide even greater operational accuracy, the time that the system changes settings should be altered, dependent on the system's loading from external temperature changes. This can be achieved by a method known as optimisation. Historical data from monitoring the system's performance can be used to calculate and adjust how long the system will take to change from set back temperature to normal operating temperatures. With optimisation the occupier sets the time the rooms are at temperature, not the time to start heating.
With all control systems the requirements should be matched to the home owner's needs and capabilities. Advanced controls need to be set correctly to enable them to deliver the potential improvements. Some customers will be keen to set up seven-day programmable thermostats in every room. Others will require a simple to operate centralised timer, which provides almost all of the benefit, without the potential confusion.
Certain types of property can benefit from additional features due to non- standard occupancy.
For instance bed and breakfast accommodation can benefit from a centralised facility to adjust room temperatures from one location. Holiday accommodation and holiday homes can also benefit from changing the operation mode or turning the system on/off remotely. Continental Underfloor Heating is able to offer features to communicate with a heating system by text message, by landline telephone or even via the Internet.
Whether an installer is looking for simple to operate controls through to advanced systems, Continental is able to advise the options available to best suit the requirements. Our expert team is on hand to offer guidance and advice. For more information visit www.continental-ufh.com or call 0845 108 7001.
