26 May 2010 02:05:48
Heat Pumps: 10 things a installer should ask
About the author: John Barker-Brown is special projects manager at British heat pump manufacturer Kensa Engineering. First published on YouGen blog: http://www.yougen.co.uk/blog-entry/1477/Heat+pumps%273A+10+things+a+good+installer+should+ask/
Finding an installer for a renewable energy technology should be a straight forward exercise. With all the certification an installer has to meet, such as the Microgeneration Certification Scheme (MCS), to enable a client to access grants, the installer has to know what they are talking about and be competent. Don’t they?
Unfortunately, with the installation of heat pumps about to explode due to the Renewable Heat Incentive (RHI) and other incentives being offered, the installer market will see a number of unscrupulous companies trying to cash in, even if they have the ‘correct’ approvals.
As an aside, there are a number of companies who aren’t approved who are more than competent, do an excellent job and have been involved in installing renewable technologies for years and are not MCS approved simply as it can be a difficult and onerous process particularly for one man bands, but that’s a different subject. [NB: if you want to benefit from the RHI, you will need to use a MCS accredited installer - ed]
It therefore pays for the client to still do their homework on any potential installer/supplier.
The normal guidelines for entering any contract will apply, such as: references - preferably actually talking to previous clients - ideally ones who have lived with the technology for at least a year; talking to a number of companies to obtain comparable quotes; trade associations, etc.
However you would also expect the installer/supplier to ask you questions, and these questions, or lack of them, should give you an indication of whether the company actually knows what it is talking about.
This should be one of the first questions the installer/supplier should ask as it will determine whether heat pump technology is right for the building. See my blog on whether heat pumps are suitable for your home).
A Standard Assessment Procedure (SAP) can be used to calculate the size of a heat pump suitable for the property as it takes into account the form, construction and insulation levels of the property. It can also be used to check the insulation levels of the property.
In the absence of a SAP, the overall area of the building can give an installer/supplier an initial indication of the size of the heat pump required.
UFH (under floor heating) or radiators? This will determine the efficiency of the heat pump and will impact on your fuel costs and hence payback.
Is solar thermal being installed? The heat pump can provide domestic hot water if required, however the installer/supplier needs to be aware of this as it does have an impact on the amount of ground arrays and the equipment supplied. DHW is an additional load on the ground and is all year round so the ground arrays need to be increased, also any hot water cylinders need to have oversized coils due to the lower temperature generated by heat pumps.
Floor construction can again have an impact on efficiency for example for a joisted underfloor first floor system the flow temperature has to be higher than the magical 35oC always quoted for underfloor, as the heat has to be driven through the floorboards.
Some manufacturer’s single phase heat pumps are limited in size (Kensa can offer a 24kW, which is one of the largest in the market place). Three phase is better as the heat pumps are more efficient and it is a more stable electricity supply but expensive to put in.
For ground source heat pumps horizontal arrays, i.e. slinkies or straight pipe roughly twice the area to be heated is required for these. If this isn’t available then the alternative is boreholes. While equally effective they can be expensive.
Ground source are a permitted development, but air source currently still require planning permission.
This should be quoted at standard conditions as laid out by EN14511-2 and should provide a means of comparing like for like. Any other standard will give different figures. In fact COPs from one brand to another should be roughly the same as many will contain similar if not the same key components