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Radiant floor heating works beautifully with a GCHP system...they seem to be meant for each other! But the design of the radiant floor system affects the efficiency of the heat pump, the capacity of heat pump needed, the size (and cost) of the GHX needed, the longevity of the compressor, and even the noise made by the compressor. An article about the efficiency & capacity of the heat pump can be found in a previous blog article. In this article I'd like to talk about how it affects the size of the GHX.      11/23/2013 Too much of a good thing!GCHP system designers and contractors working in colder climates need to protect the heat transfer fluid from freezing if the temperature of the GHX is expected to drop below about 40°F (5°C). Adding antifreeze to water increases the density and viscosity of the fluid and changes the flow characteristics of the fluid. As the fluid is cooled by the heat pumps the density and viscosity increase and can result in temporary failure of the system.       There is a common misperception that the capacity of the heat pump is what determines the size of the GHX. Many times I’ve heard a contractor say that he installed a “5-ton loop” (17.5 kW loop) for a home. What if he installed a 6-ton (21 kW) heat pump in the home rather than a 5-ton (17.5 kW)…would the size of the GHX have to be increased? Or if a 4-ton (14 kW) heat pump was installed, would a smaller GHX work as well?     The Oasis Leisure Centre in Kalgoorlie Boulder, WA, is now heated by one of the largest closed loop geothermal systems in the State. The system is unique in a couple of respects. Even though the facility is in a hot climate, with summer temperatures as high as 46°C (115°F) and deep earth temperatures at 23.5°C (74.3°F), the building requires more heating than cooling. There are two reasons for this:      Walmart stores recently built their first new store built with 100% LED lighting in South Euclid, OH. In addition to the LED lighting, lighting controls use sensors to take greater advantage of daylighting in the store and daylight harvesting to reduce energy use for lighting by a further 25%. In addition to the lighting changes, the store boasts a white membrane roof to reduce solar heat absorption. These measures, combined with efficient air conditioning systems make it one of their most efficient stores. These measures help make the integration of a GCHP system even easier. 10/17/2013 Importance of recording GHX temperaturesThe best system diagnostic tool you can have as a GCHP system designer, a service technician, a building manager or owner, is an ongoing record of the fluid temperature leaving the GHX and entering the heat pump. This can tell you if the system is operating as it should or not. What does this mean for the different stakeholders of a system? 10/12/2013 At the IGSHPA ConferenceI can't remember leaving the IGSHPA Conference without finding at least a few things that made the time and trip worthwhile. One of the things I saw on this trip was a new product that looks like it can make HDPE pipe connections quicker and easier. Watts Water Technologies had the new product on display in their booth. I spoke with Keith Whitworth and Steve Barrett in their booth who described the new HDPE pipe joining method. Much of my career in the geothermal industry has been based in North America. The principles the geothermal industry works on in North America is the same as industry in Europe, Austral-Asia, South America and the rest of the world works on...but quite a few of the little details about how systems are deployed are different in the different regions. One of the biggest differences is...   Heat transfer fluid is used to move energy to and from the ground to a heat pump in any ground coupled heat pump system. In a hot climate energy is transferred from the building to the ground by heating water to a temperature higher than the ground temperature. Fluid temperatures from the heat pump can reach temperatures as high as 90° to 100°F (32° to 38°C), In a cold climate, however... The land area and amount of pipe needed in a horizontal GHX is directly related to the thermal properties of the soil it is buried in. This in turn relates directly to the cost of installing a GCHP system...and if your customer feels it's too expensive to install they typically resort to installing a conventional system and forget about the heat pump system. To make it worse, that potential customer will often tell his or her friends they considered it for their home, but it was too expensive...they'd never get their money back. Is there any way of avoiding that? |
Ed Lohrenz
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from. Archives
September 2021
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