Finally, .....a clear, understandable explanation of how heat pumps work. This is an absolutely excellent description and visual representation. Thank you for doing this. I'd think this should be a course credit as you're such a good teacher!
Enjoyed the great explanation and graphics and then showing the parts that make it work. Some comments below are skeptical of the 1KW input to 4KW output. The energy input is the compressor motor. The 4KW is an equivalent measure of the amount of energy absorbed from the ground or pond or lake through the long loop being heated.
Very good video. I'm used to seeing from the physics point of view, being an armchair scientist. Engineering perspective was nice for a change. Guy does an excellent job showing off the entire system and explaining the processes behind refrigeration etc.
Great explanation - I am from Australia we are going to be using in ground heat pumps for heating, cooling and hot water. We will also be using PV/batteries storage for the energy required by the IGHP. We are building very energy efficient prefabricated buildings. Over the next six months, we will the designed whole development which will include all our integrated energy systems. It is shame you are not in Australia
Hi Ian. Thanks so much for your feedback. We do have a distributor in NZ who can supply Australia - Peak Plumbing (www.peakplumbing.co.nz). Let us know if we can be of any further assistance. Thanks
Just f***ing wow! I finally am starting to get it at last. So so well explained. As he talked questions popped into my mind and he miraculously answered them. Thank you so much!
Great video, really clear explanation. One thing that has stuck me before is that ground source heat pumps have a reduced efficiency compared to an air source heat pump when the external air temperature is higher than the ground temperature. Would it be possible to create a hybrid type system which alternates between a ground coil and a surface mounted condenser to get the best of both worlds?
Hi Richard, you have raised an interesting and valid point here. At Kensa we did big project a few years ago to investigate the viability of creating a hybrid ground/air source heat pump using air in the summer, which as you correctly state will normall be warmer than the ground. Unfortunately we didn't get quite the results we all expected, it turned out that the energy consumed by the fan needed to move the air often exceeded the saving in heat pump efficiency. The air had to be around 8°C warmer than the ground to 'break even' in terms of efficiency. Unfortunately in the UK (where almost all our products are sold) the number of days per year when this happens is really quite small. Our conclusion was that the extra cost of the air source components would never be recovered in running cost savings, so such a heat pump is, sadly, not economic in the UK. The power consumed by the fan also explains why air source heat pumps are, on average, less efficient than ground source.
Hi, thanks for the feedback. That's interesting to hear, but makes total sense. I can appreciate that in the majority of cases, demand drops off significantly during the summer, and as you say, the few days where the air temperature is >8oC higher than the ground temperature AND there is also demand for heating are few and far between, so not surprising its not financially viable. If the demand profile where different though (eg you were using the heat pump to serve a high year-round domestic hot water heating demand) and there were a significant demand during the summer months also, I can see it would be more of a viable option. If you ever need anything like this investigating theoretically, I run a thermal analysis consultancy; www.GreenliteEA.co.uk. There isn't currently an explicit method of modelling ground loops within the software I use (IES Virtual Environment), but it can interface with third party modelling software like Gaia Geothermal. The benefit of a thermal model is, you can model various different design strategies, and run them in parallel using identical weather data and user behavior - thus removing several key variables which are otherwise difficult to control.
Best explanation that I have seen, thanks! (I'm saving this link) I'm planning on taking a 3 year course in Energy Systems Engineering Technologies in Ontario Canada commencing in Sept. 2014.
Hi. Great video, really well explained, you turned magic into science. I'm looking forward to getting a 16kW (twin 8kW) installed in a few months. Michael :-)
At the end i understand the example with bicycle pump. Is useful to add a water tank during worm days to the ground water circuit heated by solar panels?
Yes, we are seeing some customers using solar panels and other sources of free heat to warm the ground arrays, within limits this lifts the system efficiency by approximately 2% for every 1°C increase in source temperature.
Is it better to position a heat pump in a southerly direction so it gains as much as possible from solar gain. My current option is in an area that permanently in the shade, so a sunken basement of sorts. How would you know if your current radiators would work with replacing a gas boiler/heated water tank based system to an air pump with the existing radiators. Underfloor heating would be difficult to retrofit. Is there a quantifiable benefit of either integrating it with a small solar thermal or solar PV roof panel.
With a GSHP, the location of the heat pump itself is almost irrelevant, unlike an ASHP it's not trying to collect energy from its immediate surroundings. With any heat pump retrofit, to check if the current radiators will be adequate it is necessary to perform a room-by-room heat loss calculation and then check the output of each installed radiator at the heat pump operating temperature. It is often found that radiators were oversized originally so are sufficient, especially if the insulation of the building has also been improved recently. Solar can be a good partner to a heat pump, although it won't help much in the depths of winter, in the summer it should provide most of the hot water and will assist in spring and autumn, reducing running costs when considered annually.
Does a ground source heat pump not cool the surrounding earth, enough that the land can no longer transfer the same heat. This presumes its not summer where the land is absorbing solar heat during the day. Can the same heat pump work in reverse and dump heat into the ground and offer aircon and again can you keep dumping warmth into the ground without heating it up locally
Yes a GSHP does cool the ground, it extracts thermal energy so the temperature will fall as you say. However, new energy is arriving to rewarm the ground all the time, this comes mostly in the form of sun, rain and a small amount also comes from the core of the earth. Part of the process involved in designing a GSHP system is calculating how much energy will be extracted and how much will arrive, the two need to be in equilibrium otherwise over cooling of the ground will indeed occur. Kensa is aware of some installations performed by competitors where this has indeed happened and the systems have failed. Yes GSHP's can operate in reverse, cooling the house and warming the ground, until recently the UK market has not seen much interest in cooling, but this is changing, Kensa will soon be offering cooling as an option on many models of heat pump.
I gratefully accept your offer: I'm no scientist, but I know you can't get more energy out than you put in. So, to get 200W (say) of energy out of the system I put in 50W of electricity in through the compressor motor. Where does the other 150W (or more) come from? I can only imagine it is the sum of energy from the 5-10ºC transfereed to every inch of the underground tubes. Is that right. Is there a danger of that ground heat diminishing over time due to heat pump use?
Hi Miguel, the other 150W of energy is absorbed from the ground, this is what the ground array does, it supplies low temperature heat energy to the heat pump. You are right that over time the temperature of the ground would diminish over time, when designing a system we need to use enough ground to ensure a reliable supply of heat all winter long. During the summer, when the building heating system will be mostly turned off, the heat in the ground is replenished by sunshine and rain water, ready for the next winter ahead. The ground acts like a giant energy storage tank, but of course the annual refill is delivered naturally for free!
Abdelrahman AK My understanding is that this system would only be capable of heating as the condensor coil is underground absorbing heat from the ground. If the condensor coil was also in the home (on a separate loop from the evaporator coil) this could absorb heat from the air instead of the ground thus cooling the air in the home.
+Abdelrahman AK All Kensa’s Compact and Plantroom heat pumps can operate in reverse-cycle mode providing chilled water to cool a building and operates in a similar manner to a chiller. For further in formation on this visit the link www.kensaheatpumps.com/the-technology/specifications/cooling/
I have to agree with Miguel Urdaci, the statement (1kW consumed generates 4kW) is wrong you cannot create more energy or the same amount of energy out of a system than what you put into it.(First law of thermodynamics) Otherwise our energy crisis is solved and we all have free energy or close to free energy. It all boils down to the efficiency of the system. this is more efficient that conventional geyser (electric resistance boiler). meaning you use up to 4 times less energy to generate the same amount of heat energy than a conventional geyser.
Hi Convanr, you are entirely correct, one of our favourite quotes at Kensa is 'energy can not be created or destroyed' which of course came from Albert Einstein. To answer your question, in the case of a typical small heat pump with a 4 kW heat output, that energy comes from a combination of two sources, 1 kW or it comes from the electricity input, the other 3 kW is absorbed by the ground arrays - heat energy naturally moves from the warmer to the colder, the heat pump makes the fluid in the ground array pipes colder than the surrounding ground materiel, so heat energy moves from the ground to the fluid. This free energy is then squeezed in the heat pump to raise its temperature. So yes this heat pump costs you 4 times less in electricity than a simple electric heater, for the same amount of heat output.
