The efficiency of any water source heat pump is dictated by the temperature of the water loop. Create an hourly report output showing geothermal loop temperatures. You can then check this against the heat pump chart to determine if your heat pumps are operating efficiently. Depending on the ground temperature, a geothermal system can start to heat up, lowering the efficiency of attached equipment. However, I would still be surprised to learn that an air source heat pump still performed better.<br>
<br>Also, in order to make variable volume pumping work properly, you must specify Isolation valves on the heat pumps. This allows water to bypass any heat pumps that are not calling for water flow. This lowers the pressure in the system.<br>
<br>--<br>Karen<br><br><div class="gmail_quote">On Wed, May 14, 2008 at 9:05 AM, Demba Ndiaye <<a href="mailto:demba.ndiaye@setty.com">demba.ndiaye@setty.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Thomas, </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">You should definitively have more savings
than that, even if there is the pump energy. </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">One first thing to check: the efficiency
of GSHP should be much higher than that of air-source heat pumps in both
heating and cooling modes. </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
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<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">______________</span></font><font color="navy"><span style="color: navy;"></span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Demba
Ndiaye</span></font></p>
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<p><b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma;">
<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>
[mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b><span style="font-weight: bold;">On Behalf Of </span></b>Tom Butler<br>
<b><span style="font-weight: bold;">Sent:</span></b> Tuesday, May 13, 2008 5:53
PM<div class="Ih2E3d"><br>
<b><span style="font-weight: bold;">To:</span></b> <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
<b><span style="font-weight: bold;">Subject:</span></b> [Bldg-sim] Space Cooling
Energy Consumption with GSHP</div></span></font></p>
</div>
<p><font face="Times New Roman" size="3"><span style="font-size: 12pt;"> </span></font></p><div><div></div><div class="Wj3C7c">
<p><font face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial;">I
am modeling an apartment style dormitory for a project in Atlanta, GA.
Each of the 45 units is served by its own heat pump, along with a few zones for
public areas. For an energy efficiency grant application I have compared the
designed system, a ground source heat pump, with an air source heat pump
prescribed by 90.1. Other than the systems, the models are identical. </span></font></p>
<p><font face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial;">The
energy use for space cooling is significantly higher for the GSHP system
(24,000 kWh vs. 17,000 kWh). Because the power required to run pumps offsets
the savings in heating energy, this destroys the rationale for spending the
extra money on the Ground Source Heat Pump, as well as our chances of receiving
the grant.</span></font></p>
<p><font face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial;">Has
any one encountered this issue? </span></font></p>
<p><font face="Times New Roman" size="3"><span style="font-size: 12pt;"> </span></font></p>
<p><font face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial;">Thanks</span></font>
</p>
<p><font face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial;">tb </span></font></p>
<p><b><font color="black" face="Garamond" size="3"><span style="font-size: 12pt; font-family: Garamond; color: black; font-weight: bold;">Thomas Butler,</span></font></b>
<font color="black" face="Garamond"><span style="font-family: Garamond; color: black;">LEED
AP</span></font><b><span style="font-weight: bold;"> </span></b><br>
<font color="black" face="Garamond"><span style="font-family: Garamond; color: black;">Direct
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<br></blockquote></div><br><br clear="all"><br>-- <br>Karen Walkerman<br>Second Law Consulting<br>802-238-0980<br><a href="mailto:kwalkerman@gmail.com">kwalkerman@gmail.com</a>