[Equest-users] Fan Coil Fan Energy

[Keith Swartz]

Robby,

The PTHP system not only has a fan that recirculates inside air across the inside coil (evaporator coil when cooling, condenser coil when heating), but it also has a fan to blow outside air across the outside coil (condenser when cooling, evaporator when heating). The fan coil has only the inside fan. Perhaps the program is accounting for the energy for the outside coil fan, which might explain the 15% additional fan energy.

_____________________
Keith Swartz, P.E., LEED AP
Energy Engineer / Senior Project Manager
Energy Center of Wisconsin
455 Science Drive, Suite 200
Madison, WI 53711
Phone: 608.238.8276 x123
Fax: 608.238.0523
Email: kswartz at ecw.org<mailto:kswartz at ecw.org>
Web: www.ecw.org<http://www.ecw.org>

Energy Center University
Your gateway to sustainable design training and online education programs.
www.ecw.org/university/<http://www.ecw.org/university/>
________________________________
From: Robby Oylear [mailto:robbyo at rushingco.com]
Sent: Friday, January 23, 2009 12:43 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Fan Coil Fan Energy

I'm comparing two systems one is a 4-pipe fan coil system and one is a PTHP system.  All of the savings between the two runs seem to make sense except for a large difference in fan energy between the two.  I don't have detailed product information on the actual fan energy so I currently have the same kW/CFM value input for both systems.  The fan energy of the fan coil system is 85% less than the PTHP system.

I believe the problem lies with the fan coil system, because it doesn't have an option available for "Fan Control".  I have the Indoor Fan Mode set to Intermittent, which is how I believe the system would actually operate since ventilation air is being delivered from a whole house fan.

Can anyone explain to me how the FC system calculates fan power?  Why is there no ability to change the fan control option?

Robby Oylear, LEED(r) AP
Mechanical Engineer
direct: 206.788.4571
cell: 206.354.2721
www.rushingco.com<http://www.rushingco.com>
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