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ground water heat pump

ground water heat pump

ground water heat pump

(OP)
can anyone help me with the approx cost of a ground water heat pump system? i am doing a payback analysis for a system to be installed in a typical office. ignoring the building side of the system, what would be the cost of a system capable of say 200kW. this would include the borehole, pumping system, heat exchanger, pipework to and from and the return borehole. ballpark figures are fine.

RE: ground water heat pump

200 kW!?? Is this right? That's asking way too much from a ground source system.

RE: ground water heat pump

For a water to water heat pump, developing 220kW of heating, with 50 - 55 deg.C condenser water.  And 7 - 12 deg. C chilled water.

Price for Carrier chiller in the UK £ 23,000 budget.

RE: ground water heat pump

I am designing a vertical closed loop ground source heat pump system, the design cooling capacity about 6.5kW. This is for the residential application and it only used for cooling purpose. May I know what is the estimate cost of installation including borehole, heat pump unit as well as the ducting system?

RE: ground water heat pump

In the UK, we use information from the British Geological Survey. They have a large amount of information on the potential energy output of a borehole. Where larger schemes are envisaged, a test hole should be drilled (typically £5000-00).

Once done, you will have a better idea of how mainy and how deep the boreholes will need to be.

The borehole may produce 7-10Kw each so for 200kW you may need 20 or so. Very expensive.

You need to do a life cycle costing before you think about doing a ground source heat pump system.

Friar Tuck of Sherwood

RE: ground water heat pump

GSHPs save money, both in operating costs and maintenance costs. Investments can be recouped in as little as three years. There is a positive cash flow, since the energy savings usually exceeds payment on the system.
  The initial investment for a GSHP system is greater than that of a conventional system. However, when you consider the operating costs of a geothermal heating, cooling, and water heating system, energy savings quickly offset the initial difference in purchase price.
  
You need to consider the electrical work, ductwork, water hook-up, bore holes and other provisions or adaptations to your project that are required.
  
 The reduced peak load requirements would allow utilities to serve more customers and to lower fixed costs per customer, thus offsetting some increased variable costs. This would result in less cost per kilowatt, since fixed investment for new capacity is high also some utilities offer rebates or incentives to their customers who purchase GSHPs. To need to see what your state has to offer

RE: ground water heat pump

Hold on a second:  start with the basics:  reduce the building heating and cooling loads to the most practical minimum first- work on the building envelope, glazing, solar control, heat gains and losses.  THEN:  assess the building site- why boreholes?  Is there enough room, or excavation happening on site to use combination of horizontal geo-exchange field and bore holes?  Is there enough ground water for an open system rather than a closed loop system?  Is the building going to need piles - wind the geo-exchange tubes into the piling (see this link:

http://www.geothermie.at/page/english/enercret_system/incorporation_in_structures/incorporation_in_structures.html

THEN:  do an energy balance on your system- is there more heating requirement than cooling requirement?  Or vice-versa?  What is the ground conductivity and recovery capacity under load?  Example:  if the building requires more heating than cooling energy, you will be sucking more heat out of the ground compared to the heat being dumped into the ground in cooling mode.  If the ground type cannot absorb or disperse the energy, then slowly over time you can either freeze the ground system, or warm it up too much - losing system capacity in either event.  A properly sized and evaluated geo-exchange field requires a proper energy balance over the climate year to make sure you don't exceed the soil capacity to absorb and disperse the loads.  You may require a supplemental boiler or a supplemental cooling device depending on how the energy balance pans out.  

One thing that you cannot do is simply calculate a heating and cooling load and then "pick" a geo-exchange system to serve it.  There are many more steps and evaluations to consider.  A poorly designed geothermal heat pump system can use more energy and require more maintenance than other conventional systems, so make sure the "whole building" approach is taken.

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