Underfloor Heating Control Packs and Reliance Water Controls

 

 

Reliance Water Controls became involved in underfloor

heating systems in the 1980’s when underfloor heating

installers started to use Reliance products such as thermostatic

control valves and manifolds. Over ten years later, it became

apparent that the use of thermostatic valves to control the

circulation temperature in underfloor heating systems in the

UK was increasing at a dramatic rate. By this time a variation

of Reliance’s highest selling thermostatic mixing valve, the

Heatguard

 

 

®

Highflow, was being sold to a specialist distributor

in Canada to control circulation temperatures in heating

systems – a very similar application. It was then that Reliance

Water Controls decided to look at what was happening and

to devote the experiences it had gained worldwide as a leader

in thermostatic valve technology to develop control solutions

for this rapidly growing market.

History

Underfloor heating

is not a new idea;

over 2000 years

ago the Romans had

developed warm air

underfloor heating to

such an extent that

original examples (not still working) can be found all over the

former Roman empire even today.

In the early 1980’s there were still examples of the modern

warm air systems in use but these were going out of fashion

and were being replaced with wet radiator systems. At

the same time electric underfloor systems, installed in the

1960’s, were also going out of favour because of running cost

and practical control problems. The running cost problems

often arose as a result of the way they were run and the

generally poor levels of home insulation. The availability of

more sophisticated types of control and improved levels of

insulation have helped to encourage the current growth in

underfloor heating systems.

The Basic Idea

The ground floor in many houses is made up of a large slab of

concrete or is constructed with wooden joists and plywood

floors. The basic idea is to use this floor area as a radiator.

The surface temperature required to produce a comfortable

temperature in this application is much lower than in a

conventional wet radiator system, and the heat is produced

where it is most needed. Time control is also important,

because one of the shortcomings of the 1960’s electric

systems was that, to use cheap electricity, the floor area was

heated between midnight and early morning. This produced

floors that were too hot first thing in the morning and too cold

in the evening when people wanted to sit down and relax.

To overcome this problem the system could be switched on

again to give an early evening boost, and whilst this solved in

part the comfort problem, it did not do a great deal for the

economy of the system.

How the system works in comparison to a wet

radiator system

A conventional radiator system uses one or more heat surfaces

within a room. These heat the air in their immediate vicinity by

radiation and convection air currents around the room then

distribute this air. Doorways and windows, which create their

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3

UNDERFLOOR Heating Controls

own airflows, will also affect the heat distribution. This results

in the colder air being at the floor level and much warmer air

at ceiling level. Some products advertised as ‘saving wasted

heat’ or even ‘using free heat’ use this effect. These consist of

a de-stratification fan that takes the warmer air at ceiling level

and discharges it at floor level. Even with extra air circulation

the room will have hot and cold spots within it. A further

disadvantage of air circulation is that it will distribute dust as

well as the heat. A modern underfloor heating system works

almost completely by radiating heat. Furniture will reflect

and absorb this radiated heat. By absorbing heat they also

become secondary heat emitters. This results in a much more

even heat distribution, and the air at floor level being warmer

than that near the ceiling. This type of heat distribution is also

more comfortable for the people using the room. People

often say that if their feet are comfortable then they are

more likely to be comfortable in themselves. However it is

important that one’s feet do not get too hot.

Health & Safety Implications

If an underfloor heating system is run so that the floor surface

temperature goes above 29°C then there is a greater chance

of thrombosis, but there is no danger of being burnt on a high

temperature surface. With wet radiator systems the radiator

surface temperature is the same as the circulating heated

water. This can be as high as 80-85°C, but lower surface

temperature radiators are available which protect the room

users from contact with high temperature surfaces. The fact

that there is much lower air movement with underfloor

heating systems has already been mentioned, as well as

the resultant effect on dust distribution. This can be very

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important for people who have some of the more common

dust allergies. Underfloor heating also has the major advantage

of depriving the common house dust mite of the one thing

it needs to survive and reproduce – “moisture”. Without

moisture the house dust mite will simply die. Underfloor

heating maintains a much higher relative temperature in

carpets and consequently reduces the amount of moisture

available.

The Control System

All underfloor heating systems work on a lower temperature

than a radiator system. Normally a radiator system will have

82°C hot water for the flow, the underfloor heating will run

at much lower temperatures in the region of 35 to 60°C,

depending on the floor construction and the building. The

tempering or blending valve is the heart of an underfloor

heating system. It blends colder water from the underfloor

heating system return with hot water from the heat source

to supply the correct temperature of water to the underfloor

pipework. The required temperature will vary depending

on the type of flooring and the sub-floor structure but as

these valves are adjustable the correct temperature can be

easily obtained. Reliance has been supplying a version of

the Heatguard

 

 

® TMV2, called Heatguard®

UFH, for use in

underfloor heating systems for some time. As the floor area

served in domestic applications has increased so the required

flow rate has also increased. To keep the physical size of the

control assembly within reason, Reliance has developed a new

valve with a shorter fitting dimension yet 50% more flow. The

new 28mm Heatguard

 

 

®

UFH is able to supply a 250m² system

Underfloor Heating Controls

Controls

 

There are many ways of controlling the underfloor heating.  Below picture shows our standard manifold with the wiring centre, actuators, pump and mixing valve.  

 

 

The most energy efficient system is to use underfloor heating and a condensing   boiler, however almost any boiler can be used with our underfloor heating.

We have selected our suppliers carefully to ensure we use products of the highest quality possible.  All of our standard systems are individually room by room controlled with Danfoss digital programmable room thermostats TP5000 Si.  The wiring centres, room thermostats and actuators are all made by DANFOSS – one of the market leaders within the heating controls industry throughout Europe.

The control packs are all fitted with GRUNDFOS pumps and RWC mixing valves.  The manifolds are manufactured in Germany to the highest quality possible.