[Equest-users] Variable Speed Pump

[Bishop, Bill]

Tim,

Do the boilers have their own circulating pumps? Right now you just have
a single pump handling two boilers and a decent-sized hydronic loop.
Also, verify the control valve type. You have three-way at the system
level and mostly two-way for the baseboards. You could also try
combining the VFD with a reset schedule for the HW loop since you
probably don't need 180F water all year.

Regards,
Bill

William Bishop, EIT, LEED(r) AP | Pathfinder Engineers LLP
Mechanical Engineer
 
134 South Fitzhugh Street
Rochester, NY 14608
T: (585) 325-6004 Ext. 114
F: (585) 325-6005
bbishop at pathfinderengineers.com
 
www.pathfinderengineers.com
P Please strive to live sustainably.
-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Tim
Johnson
Sent: Wednesday, September 23, 2009 10:58 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Variable Speed Pump

I am running several ECM's for a retro-commissioning project.  One of
these ECM's is to put a VFD on the heating water pump.  When I do this
in eQuest, it decreases the electric consumption but increases the gas
consumption resulting in a net increase in annual energy consumption.  I
have gas fired boilers providing heating for the building.  I have run
some hourly reports and it looks like the single speed pump is adding
more heat to the water loop than the pump with the VFD.  This seems
reasonable to me, but it doesn't seem like it would result in more
energy use than it would save.  Could you shed a little light on this
subject for me?

Thanks,

Tim Johnson, EIT, LEED AP
P: (208)577-5645
F: (208)343-3531
timj at ctagroup.com