<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=us-ascii">
<META content="MSHTML 6.00.2900.2873" name=GENERATOR></HEAD>
<BODY>
<DIV><SPAN class=937325917-26072006><FONT size=2>Hello,</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>I am having trouble
understanding the behaviour of an air source heat pump in DOE2.1E and would
appreciate any helpful insights. The system has ample supplementary electric
resistance heating capacity, but is still unable to maintain heating sepoint
conditions during cold spells (typically starting just above the freezing mark)
in the early morning occupied periods (yes, there is a thermostat setback). I
have created hourly reports (all in SYSTEMS), which show:</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>1. System variable 78 (total
heating capacity) is always large - in this particular case, about 200,000
Btu/h</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>2. System variable 43 (adjusted
capacity of heat pump in this hour) changes moderately with changes in outdoor
air dry bulb - about 40,000 Btu/h when OA temp=32F</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>3. System variable 166 (output
of unit) is the same as variable 43 sometimes, typically when OA temp is about
36 or 37F - if OA temps are lower, variable 166 values are much lower than
variable 43 (down to about 26,000 Btu/h)</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>4. System variable 5 (total
central coil heating energy input) typically matches variable 166 in more
moderate OA temps, but greatly exceeds this variable when OA temps are lower
than about 38F (reaching a peak of about 75,000 Btu/h)</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>5. Zone variable 48
(supplemental heat load for zone's heat pump this hour) is always
zero.</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>Some questions that come to
mind:</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>1. Does the adjusted capacity
of the heat pump (var. 43) not include the effect of the defrost cycle? Is this
why the output of the unit (var. 166) is lower?</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>2. What does variable 5
represent? Does it include supplemental electric resistance heating? Defrost
energy? (in this case, defrost type is resistive, the
default)</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>3. Can zone variable 48 be
trusted? Is supplemental heat being delivered? If not, why?</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>For completeness, some
pertinent system inputs are shown below.</FONT></SPAN></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2></FONT></SPAN> </DIV>
<DIV><FONT
size=2> MAX-SUPPLY-T
=
110<BR> HEAT-SOURCE
= HEAT-PUMP<BR> HEATING-CAPACITY
=
-54589<BR> HEAT-SET-T
=
110<BR> HEATING-EIR
= 0.2762<BR> HP-SUPP-SOURCE
=
ELECTRIC<BR> HEAT-CAP-FT
=
SDL-C52<BR> HEAT-EIR-FT
=
SDL-C57<BR> HEAT-EIR-FPLR
=
SDL-C62<BR> MAX-HP-SUPP-T
= 40<BR> HP-SUPP-HT-CAP
=
-170650<BR> MIN-HP-T
=
23<BR> DEFROST-T
= 35<BR></FONT></DIV>
<DIV><SPAN class=937325917-26072006><FONT size=2>I have tried increasing the
airflow, but the number of underheated hours increased. Increasing supplemental
capacity has no effect. My apologies for the length of this
email.</FONT></SPAN></DIV>
<DIV><FONT size=2> </DIV></FONT>
<DIV align=left><FONT size=2>
<DIV align=left><SPAN class=005282818-24052006><SPAN lang=en-us><FONT
face=Arial>Stantec's North <SPAN class=453122720-24052006>Vancouver</SPAN>
office relocates as of May 29, 2006, please note the new address, telephone
and fax. The email address remains the same<SPAN
class=453122720-24052006>:</SPAN></FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=005282818-24052006><SPAN lang=en-us><FONT size=+0><FONT
size=+0><SPAN class=453122720-24052006><FONT face=Arial><FONT
size=2></FONT></FONT></SPAN></FONT></FONT></SPAN></SPAN> </DIV>
<DIV><SPAN class=005282818-24052006><SPAN lang=en-us><SPAN
class=453122720-24052006><FONT color=#0000ff><FONT face=Arial><STRONG><FONT
color=#000000>Derek Whitehead</FONT></STRONG><BR><SPAN
class=453122720-24052006></SPAN><FONT color=#000000>Sustainable Building
Analyst</FONT><BR></FONT><FONT face=Arial><FONT color=#000000>Stantec <SPAN
class=453122720-24052006>Consulting Ltd.</SPAN><BR>1100 - 111 Dunsmuir Street
<BR>Vancouver, BC, V6B 6A3 <BR>Ph: <SPAN
class=453122720-24052006>604-696-8383</SPAN></FONT></FONT></FONT></SPAN></SPAN></SPAN></DIV>
<DIV><SPAN class=005282818-24052006><SPAN lang=en-us><SPAN
class=453122720-24052006><FONT color=#0000ff><FONT face=Arial><FONT
color=#000000><SPAN class=453122720-24052006></SPAN>Fx:
604-696-8100</FONT> <BR><SPAN class=453122720-24052006><A
href="mailto:dewhitehead@stantec.com">dewhitehead@stantec.com</A></SPAN></FONT></FONT><BR><A
title=http://www.stantec.com/ href="blocked::http://www.stantec.com"><FONT
face=Arial>www.stantec.com</FONT></A><FONT face=Arial color=#0000ff>
</FONT></SPAN></SPAN></SPAN></DIV></FONT></DIV>
<DIV> </DIV><PRE>
===========================
You received this e-mail because you are subscribed
to the BLDG-SIM@GARD.COM mailing list. To unsubscribe
from this mailing list send a blank message to
BLDG-SIM-UNSUBSCRIBE@GARD.COM
</PRE></BODY></HTML>