ASHRAE Journal - April 2013 - 9

letters
Pump Power and 90.1

FEBRUARY 2013

ASHRAE
JOURNAL

In February’s “Long-Term
Commercial GSHP Performance, Part 7: Achieving Quality” by Steve Kavanaugh, Ph.D.,
Fellow ASHRAE, and Lisa Meline, P.E., Member ASHRAE,
under the paragraph heading,
“Changes to ASHRAE StanCommercial Kitchen
dards,” the authors state “It
was discovered that systems...
(unitary, one-pipe, and common
loops) are now non-compliant
with the recent updates to the mechanical section of ASHRAE/
IES Standard 90.1-2010 (Section 6.5.4.4).”
I reviewed that section of Standard 90.1-2010 and could not
determine exactly what he was speaking about. I can surmise
some theories, but I would like him or someone else to expand
on why those types of systems are non-compliant.
Tyson Scheidecker,
Associate Member ASHRAE,
West Des Moines, Iowa
THE MAGAZINE OF HVAC&R TECHNOLOGY AND APPLICATIONS

ASHRAE.ORG

Ventilation

R-22 Hard Act to Follow | Quality and GSHPs | Designing Thermally Active Floors

IT Load Profile in Data Centers | Revisiting Centrifugal Compressors

The Author Responds
Standard 90.1-2010 (Section 6.5.4.4) requires that systems
with total pump power greater than 5 hp have controls that
result in pump demand of less than 30% of design wattage
when water flow is 50% of design water flow. Current practice with unitary, one-pipe, and common loop GSHPs are
on-off, constant speed pumps that have 50% design wattage
at 50% flow.
What is absurd about this requirement is that Standard
90.1-2010 has no limit on design pump wattage. Therefore,
a 100-ton system with a design pump power of 5 hp and
a demand at 50% design flow of 2.5 hp is unacceptable,
while a 100-ton system with a design pump power of 25hp is compliant as long as the power at 50% design flow
is 7.5 hp or less.
Standard 90.1-2010 (Section 6.5.4.4) also requires that
heat pumps have automatic two-way valves. Unitary, onepipe, and common loop GSHPs avoid the use of these
valves since they are unnecessary, add head loss, and create a maintenance concern to systems that are otherwise
very simple.
Steve Kavanaugh, Ph.D.,
Fellow ASHRAE,
Tuscaloosa, Ala.
ASHRAE Journal welcomes your letters. Please send them
to the editor, Fred Turner, at fturner@ashrae.org.
www.info.hotims.com/44631-1

April 2013

ASHRAE Journal

9



ASHRAE Journal - April 2013

Table of Contents for the Digital Edition of ASHRAE Journal - April 2013

ASHRAE Journal - April 2013
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Ground-Coupled Heat Pump and Energy Storage
Fan Efficiency Requirements for Standard 90.1-2013
Technology Award Case Studies:
Geothermal for 5 Ecosystems
Holistic HVAC Design
Standing Columns
Engineer’s Notebook
Data Centers
Emerging Technologies
IAQ Applications
Refrigeration Applications
Special Products
People
International Column
Energy Modeling
Products
Classified Advertising
Advertisers Index
ASHRAE Journal - April 2013 - ASHRAE Journal - April 2013
ASHRAE Journal - April 2013 - Cover2
ASHRAE Journal - April 2013 - 1
ASHRAE Journal - April 2013 - 2
ASHRAE Journal - April 2013 - Contents
ASHRAE Journal - April 2013 - Commentary
ASHRAE Journal - April 2013 - 5
ASHRAE Journal - April 2013 - Industry News
ASHRAE Journal - April 2013 - 7
ASHRAE Journal - April 2013 - 8
ASHRAE Journal - April 2013 - Letters
ASHRAE Journal - April 2013 - Meetings and Shows
ASHRAE Journal - April 2013 - 11
ASHRAE Journal - April 2013 - 12
ASHRAE Journal - April 2013 - 13
ASHRAE Journal - April 2013 - Ground-Coupled Heat Pump and Energy Storage
ASHRAE Journal - April 2013 - 15
ASHRAE Journal - April 2013 - 16
ASHRAE Journal - April 2013 - I1
ASHRAE Journal - April 2013 - I2
ASHRAE Journal - April 2013 - I3
ASHRAE Journal - April 2013 - I4
ASHRAE Journal - April 2013 - 17
ASHRAE Journal - April 2013 - 18
ASHRAE Journal - April 2013 - 19
ASHRAE Journal - April 2013 - 20
ASHRAE Journal - April 2013 - 21
ASHRAE Journal - April 2013 - 22
ASHRAE Journal - April 2013 - 23
ASHRAE Journal - April 2013 - Fan Efficiency Requirements for Standard 90.1-2013
ASHRAE Journal - April 2013 - 25
ASHRAE Journal - April 2013 - 26
ASHRAE Journal - April 2013 - 27
ASHRAE Journal - April 2013 - 28
ASHRAE Journal - April 2013 - 29
ASHRAE Journal - April 2013 - 30
ASHRAE Journal - April 2013 - 31
ASHRAE Journal - April 2013 - Geothermal for 5 Ecosystems
ASHRAE Journal - April 2013 - 33
ASHRAE Journal - April 2013 - 34
ASHRAE Journal - April 2013 - 35
ASHRAE Journal - April 2013 - 36
ASHRAE Journal - April 2013 - 37
ASHRAE Journal - April 2013 - 38
ASHRAE Journal - April 2013 - 39
ASHRAE Journal - April 2013 - Holistic HVAC Design
ASHRAE Journal - April 2013 - 41
ASHRAE Journal - April 2013 - 42
ASHRAE Journal - April 2013 - 43
ASHRAE Journal - April 2013 - 44
ASHRAE Journal - April 2013 - 45
ASHRAE Journal - April 2013 - 46
ASHRAE Journal - April 2013 - 47
ASHRAE Journal - April 2013 - Engineer’s Notebook
ASHRAE Journal - April 2013 - 49
ASHRAE Journal - April 2013 - 50
ASHRAE Journal - April 2013 - 51
ASHRAE Journal - April 2013 - 52
ASHRAE Journal - April 2013 - 53
ASHRAE Journal - April 2013 - Data Centers
ASHRAE Journal - April 2013 - 55
ASHRAE Journal - April 2013 - 56
ASHRAE Journal - April 2013 - 57
ASHRAE Journal - April 2013 - 58
ASHRAE Journal - April 2013 - 59
ASHRAE Journal - April 2013 - Emerging Technologies
ASHRAE Journal - April 2013 - 61
ASHRAE Journal - April 2013 - 62
ASHRAE Journal - April 2013 - 63
ASHRAE Journal - April 2013 - IAQ Applications
ASHRAE Journal - April 2013 - 65
ASHRAE Journal - April 2013 - 66
ASHRAE Journal - April 2013 - Refrigeration Applications
ASHRAE Journal - April 2013 - Special Products
ASHRAE Journal - April 2013 - People
ASHRAE Journal - April 2013 - International Column
ASHRAE Journal - April 2013 - 71
ASHRAE Journal - April 2013 - Energy Modeling
ASHRAE Journal - April 2013 - 73
ASHRAE Journal - April 2013 - Products
ASHRAE Journal - April 2013 - 75
ASHRAE Journal - April 2013 - 76
ASHRAE Journal - April 2013 - 77
ASHRAE Journal - April 2013 - 78
ASHRAE Journal - April 2013 - Classified Advertising
ASHRAE Journal - April 2013 - Advertisers Index
ASHRAE Journal - April 2013 - Cover3
ASHRAE Journal - April 2013 - Cover4
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