Underfloor Heating Controls

Control Components - What you Need to Know

In addition to standard control components used in traditional heating systems, some further items have been specifically developed, or have been adopted, for use in underfloor heating applications.

Thermostatic Mixing Valve

A self-acting thermostatic 3-port valve (TMV) used to blend water temperature down to that required for underfloor heating. It has a temperature range in the region of 35-60°C. With type of control system a dedicated underfloor heating circulator (UFHC) is always installed between the TMV and the underfloor heating manifold to pull water through the mixing valve and circulate blended warm water around the underfloor heating network of pipes.

Recommended TMV's

Manifold Injection Control Valve

A self-acting thermostatic 2-port valve (ICV) complete with remote pipe sensor. It controls the water temperature to the underfloor heating system by injecting boiler water into the return manifold which mixes with water returning from the underfloor heating circuits. As for the TMV above, the injector controller requires a dedicated UFHC circulator to circulate the blended warm water around the underfloor heating network pipes.

Recommended ICV's

Thermal Actuator

Simple, low power (3W), 230V or 24V thermo-electric heads, which are used in conjunction with room thermostats to open/close individual circuits on the underfloor heating manifold.

Recommended Thermal Actuator's

Manifold Wiring Centre

Used to simplify underfloor heating wiring installation. It allows for connection of multiple room thermostats and thermal actuators on the manifold. It also incorporates relay contact(s) to control the underfloor heating pump and provides for boiler interlock (either direct to boiler or via end switch on a motorised valve). Two versions are commercially available: Hard Wired for conventional electrical systems and Radio Frequency Controlled (battery powered) for use where installing cables is impractical.

Recommended Wiring Centre's

Electronic Water Temperature Control Set

Controller, pipe sensor, control valve (either 3-port or 4-port), and valve actuator (either 230V or 24V) sets. Used in larger domestic and commercial buildings. Sets are available for simple constant water temperature control or comprehensively variable water temperature control (weather compensation), which incorporate an outside sensor, and in some instances, an indoor room limit sensor.
Constant water temperature controllers modulate a 3-port, or 4-port, valve to maintain the mixed flow water temperature to the underflow heating system. A pipe sensor is used to measure and feedback the water temperature value to the electronic controller.
Variable water temperature controllers, commonly known as weather compensators, are similar to the above, although additional sensors are used to measure feedback values to the controller. An outside sensor detects external air temperature, and during mild weather the controller will take this into account and reduce the water temperature to the underfloor heating system, to match the reduced heat load on the building. A room sensor is sometimes also used. This can take into account the temperature within the internal space to adjust the compensated curve, although careful consideration needs to be given to its location within the building.

Recommended Temp. Control Set's

Time Control and Temperature Set-Back

For mixed heating systems, it is advisable to employ independent time switching for the differing heat emitter circuits. A solid-floor heating system will respond relatively slowly when compared to the traditional radiator heating system, and will therefore benefit from an offset in timing. For instance the underfloor system may switch on 2 hours before the radiator system, but will also need to switch off 2 hours earlier.
The response time of the underfloor heating systems is dependent on the amount of heat energy stored in the floor, which is a function of the density and thickness of the screed in solid-floor systems. To improve response times it is advisable to set-back (rather than switch off) the room temperatures by approximately 2 or 3 °C during periods when rooms are unoccupied. This can be achieved by using programmable room thermostats or set-back thermostats that have an additional terminal for the time-switch connection.
This method of control usually has the additional benefit of improving the energy efficiency of the heating system.

Recommended Time Control & Temperature Set-Back's

Variable Speed Circulating Pump Control

As well as the by-pass method illustrated in the figures above, control over water flow can be achieved by the use of a variable speed pump, which is switched off when the last valve on the manifold closes down.

Recommended Variable Speed Pump's

Electronic Digital Network Controllers

Developments in electronic control systems has witnessed the rise in popularity of centralised Network Digital Touchpad Control Panels linked to wireless digital programmable thermostats, Manifold wiring centres, and not least, connection to Internet Modems for remote activation.
These systems are capable of providing the features of control provided by other conventional means.

Recommended Digital Network Controller's

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