This document summarizes lessons learned from Harvard University's experience with installing and operating ground source heat pump (GSHP) systems. It covers lessons in design, installation, and operations and maintenance. Key lessons include the need to understand local groundwater conditions during design, properly size wells for heat exchange capacity without needing bleed water, install controls and metering, and implement preventative maintenance programs. Understanding these lessons can help GSHPs be an effective sustainable technology when appropriately designed and operated.

1. January 17, 2007
Ground Source Heat Pumps
at Harvard
LESSONS LEARNED
Presented by University Operations Services:
Environmental Health and Safety
Facilities Maintenance Operations
Green Campus Initiative
1. Part I: Are GSHPs Good for Harvard?
2. Part II: How GSHPs Work
3. Part III: Lessons Learned from Current Campus
Installations
4. Questions
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 1

2. January 17, 2007
Are GSHPs Good for Harvard?
Operations and
Environmental
Maintenance
Aesthetic
©2007, Harvard UOS
Advantages of GSHPs
Environmental Benefits
Use less energy than conventional
HVAC systems
Can significantly reduces emissions of
greenhouse gasses by using “free” energy
from the earth
Can be more efficient than conventional
heating systems
Up to 44% more efficient than air source
heat pumps, 72% more efficient than
electrical resistance heating (Source: DOE)
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 2

3. January 17, 2007
Advantages of GSHPs
O&M Benefits
Lower energy costs than conventional
air source cooling
20-50% reduction in energy bills (Source: EPA)
Lower maintenance costs
No equipment is exposed to weather
Fewer moving parts to fail
©2007, Harvard UOS
Advantages of GSHPs
Aesthetic Benefits
No cooling towers or other HVAC
equipment on roofs
No noise from HVAC equipment
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 3

4. January 17, 2007
GSHPs Can Be Good For Harvard
Properly designed, installed, and maintained
systems can be an effective alternative to
conventional heating and cooling
technology
Appropriately scaled GSHP systems can be
a successful part of Harvard’s energy
portfolio
©2007, Harvard UOS
Part II: How GSHPs Work
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 4

5. January 17, 2007
Types of GSHP Systems
Closed Loop Uses the earth as the heat
source and heat sink with
anti-freeze additive to the
loop water
All existing installations at Harvard are
open loop, standing column wells!
Open Loop Uses a surface or Standing Column Well
underground water source
(lake, river, or well) as
both the heat source and
the heat sink
©2007, Harvard UOS
Layout of a Typical Standing Column
Well Installation at Harvard
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 5

6. January 17, 2007
Pump Electrical Wire Well Head
From Heat Pump Soil
To Heat Pump
~ 100’ to pump
8” Steel Casing
Water Table
4” PVC Sleeve
Pump 500’ to
1500’
Bed Rock
Perforated Intake Area
©2007, Harvard UOS
Bleed Water
From Heat Pump
To Heat Pump
Regional Groundwater Flow
Water Discharge
from Formation
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 6

7. January 17, 2007
Understanding Bleed
To raise or lower well water
temperature, a portion of ne
d Li
lee
return water can be “bled” B
from the top of the well Return from Heat Pump
This allows fresh water to Supply to Heat Pump
enter the well column,
raising or lowering the
temperature of the well
Bleed water must then be
reused or disposed of
©2007, Harvard UOS New Water from Earth
Internal refrigeration
cycle generates chilled
or hot water to
condition the building
Typical
©2007, Harvard UOS water-to-water heat pumps (30 tons each)
Harvard Univeristy Operations Services: GSHP
Lessons Learned 7

8. January 17, 2007
Harvard Well Inventory
Pump Pump
Depth Designed
Wells Depth Capacity VFDs*
(feet) to Bleed
(feet) (GPM)
Blackstone 2 1500 Yes 110 180 Yes
QRAC 2 1500 Yes 100 180 Yes
90 Mount Auburn 3 450 - 650 Yes 100 270 Yes
Radcliffe Gym 2 1500 Yes 100 160 Yes
1 Francis Ave. 2 750, 850 Yes 100 160 Yes
Zero Arrow Street 3 1500 No
Future Projects
Byerly Hall 3 1500 Yes 100 210 Yes
Weld Hill
88 500 No N/A 680 Yes
(Closed Loop)
©2007, Harvard UOS
* Variable Frequency Drives allow a pump to run at partial capacity, which reduces energy costs
Part II: Lessons Learned from Current
Campus Installations
Harvard Univeristy Operations Services: GSHP
Lessons Learned 8

9. January 17, 2007
Lessons and Recommendations
Design
Installation
O&M
©2007, Harvard UOS
Design Know the condition and temperature
Lesson 1 of the groundwater
Learned From: 46 Blackstone, QRAC, Radcliffe Gym
Heat pumps and piping were not
designed for brackish water
Ground water at the Blackstone site is
64 degrees not 55 degrees as predicted
by the project engineer
Well water heats up quickly and can
reach more than 90 degrees during peak
summer periods
Dramatically affected bleed rate and
disposal strategy
A geotechnical engineer may not be
able to accurately predict groundwater
conditions
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 9

10. January 17, 2007
Design
Lesson 1 Recommendations
Identify local water conditions before making piping
and heat pump selections
All Harvard wells installed at 1500’ have brackish water
All Harvard wells have some level of iron in the water
Native water temperature is only know for the Blackstone site
(64 degrees)
Consider phasing construction so that wells are
completed before pipe and equipment selection or
drill a test well
Average cost to drill a well is ~$100/ft
1500’ well would cost $150,000
©2007, Harvard UOS
Design
Lesson 1 Recommendations
Install a Coupon Rack with the following Coupons:
Copper
Iron
Copper
Stainless Steel Coupon
Bacteria Stainless
Iron Coupon
Coupon
Ever thirty days have a authorized Chemical
Company analyze the coupons
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 10

11. January 17, 2007
Design Understand the function of the
Lesson 2 well as a heat exchanger
Learned at 90 Mt Auburn
Wells were designed to be
1500’ each
Drilling stopped at
approximately 550’ once
water flow rate was sufficient
Many well drillers are
accustomed to drilling
extraction wells, where only
flow rate is important
©2007, Harvard UOS
Design
Lesson 2 Recommendations
Do not short drill!
Short drilling reduces the
heat exchange capacity of
the well
▫ Likely to necessitate more
frequent bleeding
▫ Reduces the overall output
capacity of the system
▫ 90 Mt Auburn bled all
summer long
www.bestwaterwelldriller.com
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 11

12. January 17, 2007
Design Understand the relationship between heat
Lesson 3 exchange capacity of the well and bleed
Learned at all projects
46 Blackstone (bleeds more than designed)
Native water temperature was 9 degrees higher than
expected
▫ Set points for bleed had to be raised to avoid continuous bleed
▫ Bleed is still double the design volume
▫ Warmer water reduced efficiency of the heat pumps
2 Arrow Street
Specifically designed not to bleed
Achieved by upsizing well capacity
©2007, Harvard UOS
Design
Lesson 3 Recommendations
Design your system for zero
bleed
Include in construction specifications
and enforce the requirement!
Preferred strategy is to upsize heat
exchange capacity of the well field (drill
an extra well)
Due to salinity at 1500’ depth, no bleed www.dcs1.com
water reuse options have been identified
Disposal of bleed water introduces
regulatory issues and potential added
cost
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 12

13. January 17, 2007
Design
Lesson 4 Metering and controls are critical
Learned at 90 Mt Auburn, QRAC, Radcliffe Gym, 1 Francis
Without metering, well
performance and bleed rate is
unknown
Without monitoring well
water supply and return flows,
it is possible to draw the water
level below the pump
At 90 Mt Auburn one pump
was destroyed and needed
to be replaced at a cost of
$9K
©2007, Harvard UOS
Design
Lesson 4 Recommendations
Specify and install adequate well monitoring
and controls
Flow rate and temperature on supply/return and bleed
Integrate with building automation controls
Provides capability to diagnose problems, trend well
performance, and collect compliance data
Resist temptation to eliminate controls and
metering during Value Engineering!
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 13

14. January 17, 2007
Design
Lesson 5 Site wells appropriately
Learned at 90 Mt Auburn
Well head under
overhang
Pipe had to be cut
and removed in 10’
sections
Well Access
©2007, Harvard UOS
Design
Lesson 5 Recommendations
Allow for future access to wells for
maintenance and repairs
Consider well spacing when reviewing the site
plan
Thermal interactions between closely spaced wells can
reduce efficiency
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 14

15. January 17, 2007
Design Refrigerant selection should be
Lesson 6 carefully considered
R-410A, the environmentally preferable
refrigerant, has a smaller working range than
conventional R-22 (which is being phased
out)
Heat pumps operating with R-410A can handle
water up to 95 degrees before shutting down
Heat pumps operating with R-22 can handle
water up to 105 degrees
©2007, Harvard UOS
Design
Lesson 6 Recommendations
Avoid R-22 refrigerant, if possible
2010 no new equipment manufactured with R-22
2020 no new R-22 will be produced
Warmer condenser water reduces heat pump
efficiency
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 15

16. January 17, 2007
Install
Lesson 1
Understand piping and balancing issues
Learned at 90 Mt Auburn
Poorly designed pipe runs prevented water from
returning evenly to the three wells
This imbalance in water flow reduced the design
capacity from 150 to 120 tons
Ongoing problems have prevented full
commissioning of the building
©2007, Harvard UOS
Install
Lesson 1 Recommendations
Insist on Coordination
Drawings prior to layout
and installation of piping
Develop an owner’s
acceptance process to
ensure proper balancing
and full commissioning of www.nj.com
all systems
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 16

17. January 17, 2007
Install Positioning of the sleeve and return piping
Lesson 2 impact performance
Learned at Blackstone and 90 Mt Auburn
At Blackstone, a well was short
diagram
cycling because the sleeve was
installed below the water level
Return water was entering the
supply feed
At 90 Mt Auburn, return water
pipe was incorrectly installed
above the water level and had to
be repositioned
©2007, Harvard UOS *Not to scale
Install
Lesson 2 Recommendations
Utilize an owner’s acceptance process to verify
proper installation, start up, and turnover of
equipment
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 17

18. January 17, 2007
Install Prevent solvents from entering
Lesson 3 groundwater
Learned at Blackstone
Ensure that adhesives on PVC well piping
are fully cured so that VOCs (from solvents)
are not introduced into groundwater
Most well drillers do not allow proper curing
of adhesives before installing PVC well pipe
©2007, Harvard UOS
Install
Lesson 3 Recommendations
Ensure construction specifications require
PVC adhesives to be fully cured before the
pipe enters the well (or use alternative
joining method)
Monitor pipe joining process in field to
ensure compliance with specifications
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 18

19. January 17, 2007
O&M
Lesson 1 Maintenance starts on Day One!
Learned at Radcliffe Gym and QRAC
Plugged strainers at
Radcliffe Gym
caused evaporators
to freeze and heat
pumps to fail
Warranties do not
cover damage
caused by improper
maintenance! Iron sludge from strainer
at Radcliffe Gym
©2007, Harvard UOS
Radcliffe Gym: Heat Pump Condenser
Normal plate
design
Plate deformed –
Honey Comb
Deformation from freezing
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 19

20. January 17, 2007
O&M
Lesson 1 Recommendations
Have a preventative maintenance plan in
place before your system comes online
Clean strainers frequently, especially
during the first months of operation
Require installing contractor or
manufacturer to train Harvard building
operations team on primary equipment
prior to start up
©2007, Harvard UOS
O&M
Lesson 2 Do not put bleach into wells!
Learned at all sites
Many well consultants
recommend periodically adding
bleach directly to well water to
sterilize the well
This may be harmful to
groundwater supply
Bleach poured into the well can
enter the aquifer
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 20

21. January 17, 2007
Environmental Considerations
©2007, Harvard UOS
Design Identify and examine all permitting
Lesson 7 implications during design
Regulatory processes for GSHP systems are
not well defined or developed
Re-injection of groundwater may require a
permit from DEP
MWRA is currently reviewing bleed water
discharge to its system
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 21

22. January 17, 2007
Design
Lesson 7 Recommendations
Consult with Harvard EH&S early in
the design process
Carefully assess permit applicability
and requirements
©2007, Harvard UOS
Other Environmental Considerations
“The first ten feet can kill you”
Drilling into urban fill (8-30’) in the
Boston area can uncover historical soil or
groundwater contamination
Re-use displaced soil from well on-site
whenever possible
Carefully review any recommended
additives (e.g. bleach)
©2007, Harvard UOS
Harvard Univeristy Operations Services: GSHP
Lessons Learned 22