Under Floor Heating
What is it?
Under-floor heating has become a very popular with selfbuilders over the past few years mostly because it can be very cost effectively install in new builds as floors and walls don’t have to be uprooted.
It is an efficient home heating system, which can be used as the main source of heat or combined with another heating system. It is most commonly installed in kitchens and bathrooms where tiled floors are common, but can be used to heat the whole house. It can operate with heat pumps, a condensing boiler or from an electrical source.
There are three types of under-floor heating:
- Hydronic or wet (heated water is circulated through piping embedded in the floor);
- Air or dry (heated air is circulated through under-floor ducting) and;
- Electric (heating elements are laid under, or in, the floor)
The main advantages of an under-floor system is the even spread of heat through all of the floor, with no cold spots, and there is no loss of space to radiators as everything is beneath the floor and removed from sight.
HOW DOES IT WORK?
Wet System
The wet system operates using a system of continuous pipe loops embedded in the floor, through which water continuously circulates. The pipes contain no joints to ensure that no leaks occur, and temperatures settle at an average of 27ºC. It will work with any type of boiler that will heat water – gas, oil or solid fuel. The system’s efficiency can be maximised by using condensing boilers and heat pumps from ground source.
The system works with virtually all types of flooring including most wood. However, it is not advised to use beech, as it tends to crack, boards that are thicker than 22mm, or a very thick underlay for your carpet. Some tiles, such as terracotta, can often get a hairline crack due to the settlement of the under structure, so a latex additive could be used with the grout to combat this. Parts of the home that require higher levels of heating than others, such as conservatories, can have pipes installed in greater density which will create additional heat.
A plumber will be able to install the system, your supplier can recommend one, if required. Installation costs are higher than those involved in fitting a house with radiators. Individual thermostats control the heat in each room, and programmable room thermostats allow you to control the precision and timing of the heat levels distributed.
A wireless radio controlled system allows a central control panel to monitor and alter temperatures in groups of rooms. Because the heating is under the floor surface, there is reduced activity in terms of air movement, meaning that there is a reduction in the amount of dust in the atmosphere, which makes for a cleaner home. The low surface temperature means that air is not dried out as much as it generally is by radiators or stoves.
Dry System
The dry heating system works by heating a carbon element or cable similar to an electric blanket that is controlled by a digital thermostat timer to make it 100 percent efficient. Some run on night-rate electricity and is monitored by external and internal sensors. Additional heating may be provided using extra floor heating or ceiling heating.
There is no danger of leaks, which would ruin a wooden floor. The heat is evenly dispersed over the entire surface at the same time and can heat quicker which reduces the length of time that it needs to be on. Systems can be installed directly under tiles or floated wooden floors without the need for digging up concrete or floorboards. This will significantly reduce installation costs and disruption. No maintenance is required. It does not require a boiler and there are no leaks, as it is a dry system; however, if a cable
is damaged the damage is generally easy to locate and repair. The thermostat’s floor temperature limiting probe will protect wooden floors from overheating. Dry under-floor heating systems are often used in conjunction with wet under-floor systems, where higher temperatures may be required or a fast boost system is needed. With the dry system you can use a combined digital thermostat timer. Temperatures may be controlled in individual rooms using a thermostat in each. Under-floor heating can also be fitted where
there are wooden joists and used with wooden flooring. A dual tariff meter supplied by the ESB will give you night rate electricity from 11pm until 8am. This will give great savings on running costs.
Electric System
Electric under-floor heating uses cable or mats. It is installed above the insulation layer and beneath the floor surface and connected directly into the mains supply. It can be used in bathrooms, kitchens, conservatories, under laminate floors etc.
How much does it cost?
The price of under-floor heating is dictated by the complexity of the system and energy source used. Will the source be geothermal or a gas boiler, for instance? At the higher end of the scale, if you want to install under-floor heating across two storeys a large house the cost could be as much as €20,000. This would include all floor work, insulation and thermostatic controls in all rooms. The heating system element in this instance would cost in the region of €10,000 However if you are installing under-floor heating in a number of ground floor rooms only the overall cost should be less than €10,000.
Source: Build Your Own House & Home