We had a drilling rid turn up for a number of days and drill eight 60m deep boreholes. The holes are generally about 150mm in diameter, and a Rehau closed loop probe is first filled with water, to give it some weight, and then dropped down the 60m deep hole – it all happens incredibly quickly – more expensive than the do-it-yourself slinky installation, but alot quicker, and alot less disruptive. Bags of Cement-Bentonite are then poured down the holes to seal them and most importantly give good contact between the pipes and the wet earth, for energy absorption.
Heat pumps – the latest Green fashion accessory?
Unfortunately the general public have been fooled into believing that the use of ground source or air source heat pumps is the answer to all their green credentials. I have seen many, many properties claiming “Eco” status, just because they have a heat pump installed – this is a serious mistake. Many have seen their electricity bills quadruple as a result. I describe ALL types of heat pumps including my own as a dirty green or brown technology not GREEN. Electricity is needed to get heat out of these units, most manufacturers quote a usual COP (coefficient of performance) of 1 to 4 – for every kilowatt of electricity expended, presently approximately 12pence per KW, you get 4 usual FREE units or (48pence worth of electricity back).
Very few of these installed systems produce anything like this COP – do people even question their COP or better still do they know how to calculate it. The electricity has got to come from a GREEN source for this electrical heater to be classified as green, and the only way you can guarantee a green source of energy is to produce it yours elf via a pico-hydro source, Photo voltaic installation or a suitably large enough wind turbine. Even in a modest 4 bedroom well designed Eco house – you would need an 8 – 10KW PV array to off set the electricity consumed by a heat pump.
Only a tiny fraction of small independent electricity suppliers such as www.goodenergy.co.uk and www.ovoenergy.com are producing 100% of their supplied electricity from green renewable sources – signing up for a green tariff from the big 6 just gets you a more expensive bill.
Therefore am I against HEATPUMPS ?
No, not at all provided you understand their limitations. Firstly spend all your available hard earned CASH on insulating the living daylights out of your property – you simply can’t put enough insulation into the structure – at construction stage is the cheapest time to do it. If you have an older property that has limited insulation – PLEASE – don’t even think about a heat pump, until you have first carried out full cavity fill, retro-fitted insulation to the inside walls of your house, changed your windows or at least fitted some type of secondary glazing. And when you can honestly tell me that your U-values for your walls, floors and roofs at below 0.2 – then go out and by a heat pump.
Read the report below, it isn’t very upto date, but until the EST or Which ? magazine start rating the UK Heatpumps this is the best report we have. My heatpump is a single phase NIBE 12KW unit – FIREFIGHTER 1140. It can produce a maximum temperature of 60 degrees hot water – but note even in their own literature they state a Cop of 5 – WOW! But that is with an incoming medium temperature of 0 degrees and a 35 degree output temperature – not very good for a shower but excellent for my underfloor heating.
Changes are slowly coming into the market, forcing all Heatpump companies to start differiating their products from each other, and of course I highly recommend NIBE (faultless service and very knowledgeable from one of Europe’s largest Heat pump manufacturers), but IDM (http://www.idm-energie.at/en/terra-heat-pump.html) Heat pumps use a hot gas charging mechanism to get more FREE heat out o f their units and look at the Daikin Altherma (www.altherma.co.uk) for their range of cascading air source heat pumps that can deliver upto 80 degrees – heat pump employs two closed efrigerant systems having different refrigerants in cascade relationship to each other to address efficiency problems normally associated with this sytem.
Heat pumps don’t give you any FREE heat – just less expensive heat. If you are getting your electricity from gas or Cola powered electricity generating station, which chances you are – your carbon foot print and CO2 emissions would be lower with a A+ rated gas boiler.
However, I use the heat pump purely as a back up to my SOLAR THERMAL array – put simply despite its huge size, it is a one off investment – with minimal (15W electric motor to pump the solar water around the system) electrical demand. The SUN is FREE, and we have been able to prove that despite one of the coldest winters for 30 years (lowest recorded temperature onsite was minus 18), the solar array provided just over 92% of our hot water and underfloor heating demands throughout the entire year. The trick here isn’t the size of the solar thermal array its the huge thickness of insulation the building is wrapped in – which means just about ALL our hot water generated from the panels goes into HOT WATER HEATING not HEATING the house.