One of the fastest growing applications of renewable energy is the ground source heat pump. In this special report, Dr. Neil Watson, Technical Director of Fernox explains that although this is a positive step for the UK, we are currently seeing installation issues that could easily be avoided.
Although still fairly new to the UK, ground source heat pumps are now gaining popularity. The Government, by acknowledging the advantages of renewable technology sources, has encouraged its broader acceptance not only with the formation of the Department for Energy and Climate Change, but by setting a target of a 15% take-up of renewable energy technology by 2020. Therefore, we are likely to see far more ground source heat pumps being specified and installed over the next ten years.
Although the life expectancy of a ground source heat pump is typically 20-25 years - without the correct water treatment the system will be liable to problems leading to costly call backs for the installer and householder.
For example, for new build applications, ground source arrays are installed during the ground work period when the foundations are laid. These arrays are often filled with water and left while construction continues. In these conditions, the water is stagnant and bacterial contamination or microbiological growth can quickly develop, having a negative effect on the efficiency of the system. In the worst cases, this can lead to failure of the ground source heat pump within a few months if the bacteria contaminate the heat transfer fluid.
Protection is vital and heat transfer fluids such as, Fernox HP Fill have been developed to provide biocidal protection for closed loop ground arrays. When added during installation
HP Fill will prevent microbiological contamination from developing. This means ground arrays can be immediately connected to the ground source heat pump without the need for any additional cleaning.
If cleaning is required, Fernox HP Cleaner has been developed to clean and disinfect ground arrays from the potential damaging effects of bacterial slime and other contaminants before commissioning.
In addition, many installers are unaware of the danger of not dissolving heat pump fluids properly. If the heat transfer fluid isn't sufficiently dissolved, sections of water can be left unprotected, leading to corrosion, damaged pipe work and even pump failure if these sections of water, with no frost protection, come into contact with the heat pump.
This is far more likely to occur in larger systems so to avoid this, installers should ensure that rather than just pouring the heat transfer fluid into the water it is mixed in accordance with the manufacturer’s instructions into a mixing machine and pumped through the system at the same time as the system water.
Installers can ensure the heat transfer fluid has been fully dissolved by using a Fernox Refractometer, which can determine the concentration levels. Easy to use, the installer simply opens the illuminator plate and places a drop or two of sample water onto the prism. One the plate is closed; the installer looks through the circular eyepiece to take a visual reading of the level of frost protection within the system. This reading can then be cross-referenced with manufacturer’s recommendations to ensure the system is fully protected.
The benefits of cleaning and protecting renewable technologies are likely to be further recognised in the revisions to Part L of the Building Regulations in 2010. In the proposed changes to the regulations when it comes to heat pumps, it states 'ground loops should be cleaned with a cleaning fluid and biocide as part of the commissioning process.' So it is advisable that installers ensure best practice sooner rather than later.
For further details regarding Fernox Water Treatments, please visit www.fernox.com or alternatively call Fernox on 01483 793200