FXSTD – Alternative Energy Center

By: John Mahoney
The layer under the earth surface keeps the same temperature level all year long. This means that this layer is warmer than the air temperature in winters and colder than it in summers. Increasing effect of global warming, the problems experienced because of dependency on fossil fuels and high prices associated with such fuel types made people think of ways to meet their heating needs, at least at residential level, from renewable sources. Making use of the stable temperature level of the earth is one of these methods and they are called heat pumps. According to laws of thermodynamics heat cannot flow from a colder point to a hotter point by itself. To achieve this some work should be added to the system and heat pumps do this. There are three main heat pump types:

Ground source: extracts heat stored in the ground.

Water source : extracts heat from a spring or a water source

Air source : extracts heat in air

The surface of earth can be thought of a very large scale solar collector. By transferring the heat from ground to the homes in winter or doing the opposite in summers heating and cooling needs of a house can be met at a significant level.

The systems have three main components:

Pipes Heat Pump Heat Distribution system

Pipes are buried underground. Fluid in these pipes absorbs the heat in the ground or emits it to the ground depending on the requirement. The heat pump is the piece adding the work to the system in order to provide flow of heat and the heat distribution system is the part which distributes the heat from the heat pump to the building. Generally heat is distributed in the form of hot water by means of radiators or under floor heating systems.

Advantages:

A well-insulated building's entire heat requirement can be met by a well designed heat pump. A heat pump can also heat the domestic hot water. A heat pump can heat water up to around 55°C A heat pump has a coefficient of performance around 3 or 4. This means for 1 unit of electricity you consume for a heat pump you can get 3 or 4 units of heat. If you want to compare this number with a typical system, a regular resistance heater has a coefficient of performance of 1. You can power a heat pump from a renewable energy source like a windmill, hydro or solar panels (and this would introduce more environmental benefits) Heat pumps can run continuously without a rest and they are generally sized to exactly match the heating requirement of your building. However for a boiler system the situation is opposite. As they are generally designed to be larger than they need to be to be able to stay on the safe side they are quoted at higher capacities. They operate for approximately 20 years. They can be coupled with under floor heating systems so that you can save more energy. Your heating needs can be regulated according to the outside temperature. This means you will need more heating when it is -5oC outside and obviously less when it is +5oC. Many heat pump systems come with this system already integrated and it is called "Weather compensation". They hardly need maintenance and they need no cleaning If you are building a new house you can cover the extra cost with your mortgage and finance the installation at a low cost They are eligible for SEI grants

Some points to keep in mind while planning to have a heat pump installed:

Quality is one of the most important things to consider while choosing a heat pump system or an installer.

Only choose a heat pump with a recognised certificate of quality and performance. Your heat pump and its heat source should be designed by a professional to meet the heating requirement of your house (not more or not less). Choose an installer with the proper training and experience in this field. Make sure your system has been thoroughly checked and commissioned before signing off the installation.