Underfloor Heating

Radiant Heat

Radiant Floors delivers heating systems suited for all room types. In new buildings, it can be decided during the planning phase which rooms are supposed to have under floor heating. This allows a unique opportunity to design a tailor-made heated floor for optimal comfort and efficient use of energy.

Radiant Heating Defined

Radiant heat is similar to the energy of the sun! We all know the warmth of basking in the glow of direct sunlight on a cool day. Thermostatically controlled radiant heating works the same way. Underfloor heating is installed below the floor surface and top floor, but the actual heating process, is by radiant heating.

Radiant energy will heat the surfaces of all objects which are in direct line of sight from the floor; that means all walls, ceilings, chairs, tables, people and pets which can be "seen" by the radiant energy. Air coming in contact with these surfaces is also gently heated.

Underfloor heating can be effectively mounted on any flat surface. The only requirement is the surface should be sufficiently large enough. The larger the surface, the lower the actual surface temperature required. A wall radiator may have a surface temperature of 80°C while a 27°C floor will do the same job.

Most underfloor heating systems operate under 65°C; floors generally less than 29°C. It is only "radiant" heating if 50% or more of the heat transfer is by radiant energy. You may be more familiar with terms like "radiant floor" or "radiators".

How Radiant Energy Works

"What exactly is radiant energy?" Hold your hand over a hot cup of coffee and feel the heat. The logical conclusion is that heat rises. Logical maybe, but incorrect! "Hot air" rises but "heat" can travel in any direction. That is why you can feel the heat of the cup when you place your hand to the side of it. Radiant energy transfer is caused by a warm surface giving up its heat to a cooler surface.

Whenever there is a temperature difference between two surfaces, both surfaces will attempt to equalize. Radiant energy travels through space without heating the space itself. It only turns into heat when it contacts a cooler surface.

Our human comfort relies just as much on radiant heat transfer as it does on air temperature, yet many heating and air-conditioning professionals still think only in terms of air temperature. As a result, many people are missing out on a truly comfortable living environment in their own homes or places of business. By controlling both the air temperature and the radiant transfer, underfloor heating systems deliver a comfort that is unsurpassed.

Temperature and Radiant Energy

Our skin surface temperature, about 29°C, is generally warmer than the surrounding surfaces. This makes us a radiant heater. Stand by a large picture window in midwinter and you will feel the heat leaving your body. If the rate at which we radiated heat is correct, we feel comfortable. When the temperature difference between our body and the surrounding cool surfaces becomes too great, we have to put on a sweater to slow down the rate at which we are radiating. When the sun beats down on us through the window, we receive heat instead, and off comes the sweater. Our normal state is to lose heat at a constant and regulated rate. We are also designed to lose heat in other ways as well. Air coming in contact with our skin conducts away heat. Our skin is moist and moving air also causes evaporative cooling. A truly comfortable environment is one designed to draw heat away from our bodies at precisely the correct rate.

A heated floor normally "feels" neutral. The floor surface temperature is usually less than our body temperature, although the overall sensation is one of comfort. Only on very cold days when the floor is called on for maximum output will it actually "feel" warm.

Heat coming from a wall radiator can be felt the closer you get to it because its surface is much warmer than your body.

Radiant systems are designed to match the heat loss of the human body in a way that is not possible by any other form of heating.

Controlling a Radiant Heating System

A simple wall thermostat is generally all that is required. The floor temperature control may be set to work in conjunction with air temperature, which adjusts the underfloor heating based on both floor and air temperature for increased comfort and economy.

There is the option to control the floor temperature only, ideal for heating in bathrooms and kitchens.

Our UFHSTAT digital thermostat has adjustable time settings and comfort temperature settings to suit each period of the day.

A big advantage is the option of a thermostat in every room. This provides additional comfort as well as energy savings because you can turn down those rooms that are not in use or that you prefer to have cooler.

Radiant Heat Response Time

Response time often refers to the time it takes for the system to raise the room temperature when the thermostat setting is increased. This is not an accurate definition of response time and can lead one to a false conclusion that radiant systems can be slower than other heating systems.

Response time should be measured by the amount of time it takes to make the occupant "comfortable". See "Temperature and Radiant Energy". In some cases, radiant systems can have a faster response time than other forms of heating.

Energy Savings

Increasing your comfort and, at the same time, saving money on your utility bill is a winning combination.

Multiple zoning to allow unused rooms to be turned down, and use of thermal mass to take advantage of the retained heat factor can reduce energy bills. Another energy saving comes from lower overall thermostat settings which you choose naturally.

When both air temperature and radiant transfer are compensated for, you feel comfortable at room air temperatures which are lower. You no longer have to force yourself to turn down the thermostat to save, you will do it automatically to be comfortable.

Heat loss from any building is driven by the temperature difference between the inside of the structure and the outside.

Conventional systems are located along outside walls, under windows and in front of sliding glass doors to compensate for all those cold surfaces. The hot air goes up those cold outside walls, across the ceiling and down. In other words, every place where there is heat loss.

This is a great setup for wasting energy. Radiant heating directs the heat to the interior of the space and reduces or eliminates the excessive temperatures on outside walls and ceilings. This can result in energy savings of 10% to 30% in most residential properties and up to 60% or more in shops, offices, showrooms and warehouses.

The Installer

Choose an installer who either has experience or has the proper training. Avoid those who appear to be flying by the seat of their pants. The industry has been around long enough that "design as you go" is not acceptable.

The installer should provide room-by-room details of your requirements, including room type and shape together with dimensions. Primary heating applications will require a heat loss calculation based on your building. Radiant Floors provide a free design service to assist all installers.

Guesses and estimates are OK for preliminary work, but nothing replaces good planning.

If in any doubt consult Radiant Floors – 01254 825 234

Overcoming Objections

Anyone who is not experienced with radiant heating may want to avoid the use of this efficient form of heating.

This is a normal reaction, and by their objection they are really saying, "I don't know enough about radiant heating and therefore do not feel comfortable working with it." At Radiant Floors we help you to overcome these objections – call 01254 825 234.

Working with professionals or trades people who are unfamiliar with the systems can result in inflated costs and a potentially poor installation.

Remember, you are the one that will live or work in the building, not the contractors. It all comes back to your desire for comfort and energy savings. Do your homework, ask a lot of questions, use a reputable installer and you will end up with a level of comfort you may not have thought possible. People, who have experienced radiant heating seldom, if ever, return to conventional heating systems.

If you need advice please contact Radiant Floors – 01254 825 234.

Make the decision for radiant heating and you will not be disappointed.