<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial, helvetica, sans-serif;font-size:10pt"><div style="color: black; font-family: arial, helvetica, sans-serif; font-size: 10pt; "></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;">A heat pump are a MUCH more </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px;">efficiency</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> way of heating. The only issue with heat pumps are that they do not work well in cold weather (<40*F) below this temperature, they are pretty much electric resistance heaters. A lot of improvements have been made, for
example, the Mitsubishi Citi M</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px;">ulti-Split</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> systems can operate at temperatures as low as 13*F. For these types of systems, they </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px;">operate</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> as Heat pumps at 40*F and above. At 40*F and below, they use electric resistance heat to warm the air flowing over the outdoor unit (</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif"
size="3"><span class="Apple-style-span" style="font-size: 13px;">allowing</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> for heat transfer between the air and the </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px;">refrigerant</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;">). So once you get down to 13*F they start to use a lot of electric resistance heating. Still much better that pure electric resistance heating!</span></font></div><div style="color: black; font-family: arial, helvetica, sans-serif; font-size: 10pt; "><div><br></div><div>-Eddie</div><div style="font-family:arial, helvetica, sans-serif;font-size:10pt"><br><div
style="font-family:times new roman, new york, times, serif;font-size:12pt"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> deepika khowal <deepika.khowal@gmail.com><br><b><span style="font-weight: bold;">To:</span></b> equest-users@lists.onebuilding.org<br><b><span style="font-weight: bold;">Sent:</span></b> Thu, November 4, 2010 2:52:38 PM<br><b><span style="font-weight: bold;">Subject:</span></b> [Equest-users] PTAC and PTHP<br></font><br>
<div>HI </div>
<div>I am trying to model a room with 80% glazing which has a wall unit air conditioner.</div>
<div>what will be the difference PTAC using electric heat / heat pump for heating ?</div>
<div>which one is advisable in terms of efficiency and energy savings?</div>
<div>does anyone has any thought on this?</div>
<div>Thanks</div>
<div>Regards</div>
<div>Deepika</div>
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