Geo-Flo NP Series Installation guide

www.geo-o.com
NP Base Non-Pressurized Flow Centers
Installaon, Operang, and Maintenance Manual
Geo-Flo Corporaon
905 Williams Park Drive
Bedford, Indiana 47421, U.S.A.
Main Number: 812-275-8513
Toll Free: 800-784-8069
Fax: [phone]

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 NPBSeriesNon-PressurizedFlowCenters 
Table of Contents
General Descripon . . . . . . . . . . . . . 1
Available Flow Center Models . . . . . . . . 2
Flow Center Pump Sizing. . . . . . . . . . . 5
Installaon . . . . . . . . . . . . . . . . 6
Flushing and Purging . . . . . . . . . . . . 8
Start Up . . . . . . . . . . . . . . . . . .13
Maintenance. . . . . . . . . . . . . . . .15
Pump High Voltage Wiring . . . . . . . . . .17
Oponal Pressure Relief Piping . . . . . . . .18
Troubleshoong . . . . . . . . . . . . . .19
NOTES:
This guide provides the installer with instrucons specic to NP Base Flow Centers. Please refer to your
heat pump manufacturer’s instrucons or CSA/ANSI/IGSHPA guidelines for addional detailed ushing,
purging, and installaon informaon. Please review the enre IOM document before proceeding with
the installaon.
Geo-Flo Corporaon is connually working to improve its products. As a result, the design and
specicaons of products in this catalog may change without noce and may not be as described
herein. For the most up-to-date informaon, please visit our website, or contact our Customer Service
Department. Statements and other informaon contained in this document are not express warranes
and do not form the basis of any bargain between the pares, but are merely Geo-Flo’s opinion or
commendaon of its products.

General Descripon
The NP Series is a family of non-pressurized ow centers used for
closed-loop geothermal (ground source) heat pump systems. The
NP Series ow centers ulize a water column to provide the neces-
sary sucon head for the circulator pump, and to ensure a ooded
pump volute. Each NP Series ow center consists of a uid reservoir
(tank), ush and/or service/isolaon valves, and one or more pumps
housed in a foam-insulated cabinet. The valves included in each NP
ow center varies within the family of products. Review the follow-
ing secon on “Available NP Flow Center Models” for more informa-
on. Every NP ow center includes a sealing cap to ensure a closed
system and provides vacuum relief to prevent the reservoir from
dropping below atmospheric pressure when the loop expands (dur-
ing cooling season). A pressure relief valve prevents the reservoir
from being over-pressurized when the loop contracts (during heang
season). Since the NP reservoir can hold pressure, the air space at
the top funcons like an expansion tank in pressurized systems. The
NP reservoir provides an air separaon funcon due to the size of
the tank and design of the return piping.
1 | Installaon, Operang, and Maintenance Manual
Figure 1 shows the uid ow to and from the NP Base ow center. The uid is pumped from the ow center’s
tank on the le side, travels up through the sucon side isolaon valve, through the pump(s), and out the dis-
charge isolaon valve . The uid returns from the ground loop through the top right tank isolaon valve and is
directed to the tank where any air present in the uid is released.
Figure 1: Generalized uid ow
(components inside cabinet)
Out: From
Flow Center
to Heat Pump
In: From
Ground Loop
to Flow Center
To tank
From tank

Available Models
The NP Series of ow centers are available in several
models to meet the requirements of the specic instal-
laon and contractor preference. The following is a
brief descripon of each NP product. Note that each NP
product has a specic installaon manual. This manual
focuses on the NP Base. Consult the manuals for each
specic NP for further informaon.
NP Base (NPB) Flow Center:
The NP Base is a cost compeve model designed for
single geothermal heat pump installaons (one heat
pump on a dedicated ground loop) where the contrac-
tor chooses to install external ush valves, or chooses to
ulize internal headers (i.e. all loop circuits are brought
into the mechanical room). The NPB includes isolaon
valves on the pump sucon and discharge, and an isola-
on valve on the return. Field connecons to the NPB
are 1” NPT.
NP Flow Center:
The standard NP Flow Center is the original NP oering
and includes Geo-Flo’s Flo-Link double O-ring technology.
The NP is designed for single geothermal heat pump
installaons. The NP includes 3-way, 4-posion ushing
and isolaon valves that allow the contractor to ush the
heat pump and ground loop without addional valves or
plumbing. This NP may also be used with internal head-
ers. The 3-way valve on the sucon side of the pump(s)
can also be ulized to ll and drain the tank. The NP
Flow Center does not ship with any ngs. Hose kits are
available for installaon ease and exibility.
NPB Series Non-Pressurized Flow Centers | 2
Figure 2: NPB
Figure 3: Standard NP

NP Plus (NPP) Flow Center
The NP Plus has the same features as the NP but also includes an
external 3-way ushing/purging valve, and a set of Flo-Link X 1-1/4”
HDPE socket fusion ground loop adapters (Figures 4 and 5). This ad-
dional external 3-way valve allows the ground loop to be ushed
separately from the heat pump. Since the ground loop adapters
are included, a hose kit or a set of Flo-Link double O-ring adapters
are all that is required for connecon to the heat pump. The NP is
designed for single geothermal heat pump installaons.
NP Dual Circuit (NPD) Flow Center
The NPD has the same features as the NP and NPP but is designed
for installaons where two geothermal heat pumps share the same
ground loop. All 3-way valves are built into the NPD. Check valves
are included in the product to prevent the need to install external
check valves on each pump circuit. Hose kits are available for instal-
laon ease and exibility.
Figure 5: NPP
Figure 4: NPP with hose kit
Figure 6: NPD
3 | Installaon, Operang, and Maintenance Manual

NP Mul Circuit (NPM) Flow Center
The NPM is a family of mul-circuit non-pressurized ow centers that are used for two or more geothermal
heat pumps sharing the same ground loop. Since there are large number of available opons for the NPM,
please consult our website or the NPM literature for detailed descripons.
NPB Series Non-Pressurized Flow Centers | 4
Figure 7: NPM with circulators for each heat pump
Figure 8: NPM with central variable speed pump and zone valves for each heat pump

Flow (U.S. GPM) [l/s]
Grundfos Pump Performance Curves (Single Pump)
Head (Feet) [kPa]
UP26-116 UPS26-99 high spd UPS26-99 med spd UPS26-99 low spd
[0.13 0.25 0.38 0.50 0.63 0.76 0.88 1.00 1.14 1.26 1.39 1.51 1.64 1.77 1.89 2.02 2.15 2.27]
[14.9]
[29.8]
[44.8]
[59.7]
[74.6]
[89.5]
[104.5]
[119.4]
Flow (U.S. GPM) [l/s]
Grundfos Pump Performance Curves (Two Pumps)
Head (Feet) [kPa]
2 UP26-116 2UPS26-99 high spd 2 UPS26-99 med spd 2 UPS26-99 low spd
[0.13 0.25 0.38 0.50 0.63 0.76 0.88 1.00 1.14 1.26 1.39 1.51 1.64 1.77 1.89 2.02 2.15 2.27]
[29.8]
[59.7]
[89.5]
[119.4]
[149.3]
[179.1]
[208.9]
[238.8]
5 | Installaon, Operang, and Maintenance Manual
Flow Center sizing:
Performance curves
The specic NP Series ow center should be selected based on the system pressure drop (including the geo-
thermal heat pump, ground loop piping, and interior piping). Calculators to assist with pressure drop deter-
minaon and pump selecon are available at www.geo-o.com/calculators. The ow center selected should
provide at least the minimum amount of ow recommended by the heat pump manufacturer for the heat
pump selected.
NOTE: The NP Base (NPB) is currently oered with UPS26-99 and UP26-116 pumps only. NP, NPP, NPD, and
NPM ow centers have addional pump opons.

NPB Series Non-Pressurized Flow Centers | 6
Installaon
Mounng the unit
The NP Series ow center must be mounted on a level surface
near the ground source heat pump. The unit can be placed on
the oor or on an isolaon pad such as a small piece of expanded
polystyrene (blue board insulaon) or a high-density rubber equip-
ment pad. Since the cabinet is plasc and will not rust, an isolaon
pad is not required for a thermal break but may be used if desired.
An-p brackets and hardware are included and can be used if
deemed necessary for the installaon locaon. If these brackets
are used, several methods of aachment can be ulized. Figures
9a, 9b, and 9c show these methods. Note that if you chose to
mount the NP to a concrete oor, the concrete anchors must be
eld provided.
Figure 9c:
Figure 9b:
Figure 9a: An-p brackets (two included)
mounted on top sides of ow center
An-p brackets mounted on
boom of ow center
An-p brackets mounted on top
of ow center
Plumbing Opons
The NPB Series ow center can be plumbed with a wide variety
of materials including HDPE, PVC, copper, PEX, and exible hose
to provide many opons to the installer. The ow direcons to
and from the ow center are shown in Figure 10. The installer can
choose to direct the uid ow from the pump(s) to the geother-
mal heat pump out the top or the front of the ow center. The
included isolaon valve should be installed in the chosen direc-
on, and the included 1” plug should be installed in the unused
port. The brass swivel half-union ngs use a at gasket and
should be torqued hand-ght plus 1/8 to 1/4 turn onto the valves
and plug. Over torquing may cause the joint to leak. If the joint
drips at start-up, snug with channel locks unl the drip stops.
Figure 11 shows a standard installaon when the ground loop
headers are external to the building. Insulated 3-way ush valves
are available, or the installer may choose to install six ball valves
for ushing the loop and heat pump. Figure 12 shows an installa-
on where each loop circuit is brought into the mechanical room
and headered.
To HP
Opon 2
To HP
Opon 1
From
Loop
Figure 10: Flow Direcon

7 | Installaon, Operang, and Maintenance Manual
Figure 11: Plumbing diagram- external headers
Figure 12: Plumbing diagram- internal headers
Plumbing Opons: External Headers
Plumbing Opons: Internal Headers

NPB Series Non-Pressurized Flow Centers | 8
Flushing and Purging
Flushing with NPB Series Flow Center (Outside and Inside Headers)
NOTICE: Using a quality ush cart is the fastest and easiest way to ensure that all air and debris is removed
from the ground loop. The ush cart must be able to provide a minimum uid velocity of 2 /s through all pip-
ing, provide ltering, and allow power ushing. It is extremely common for construcon debris, polyethylene
pipe shavings, dirt, sand, rocks, etc. to enter the ground loop piping during installaon. The wet rotor circulator
pump(s) used during system operaon require clean, debris-free uid to funcon properly. A small amount of
debris in the ground loop could become lodged between the pump’s rotor and housing causing pump failure a
few days to a few years aer inial installaon. This preventable issue is a common mode of failure for circula-
tors. Although the NP Series ow centers do have the ability to separate air from the loop uid, its pumps are
not powerful enough to guarantee that all air and debris can be ushed from every type of loop during the
inial loop installaon. Geo-Flo recommends ushing all ground loops with a quality ush cart to ensure that
the loop is free of air and debris when the loop installaon contractor leaves the job site.
Flushing with Flush Cart -- Outside Header / Using External 3-Way Valve
CAUTION: NEVER DEAD-HEAD THE FLUSH CART PUMP INTO THE FLUID RESERVOIR OF THE NP
SERIES RESERVOIR TANK. NEVER ATTEMPT TO FLUSH THROUGH THE TANK USING A FLUSH
CART PUMP. OVER-PRESSURIZATION OF THE FLUID RESERVOIR COULD BE DANGEROUS AND
WILL VOID THE WARRANTY.
Figure 13: Flushing external headers

9 | Installaon, Operang, and Maintenance Manual
NOTE: For detailed ushing and purging informaon, refer to the Flush Cart Operaon Manual for the cart
being used. Geo-Flo provides detailed instrucons on operang the ush cart manufactured by Geo-Flo.
1. Close all three isolaon valves on the NPB.
2. Remove the cap from the NPB tank. This step is precauonary and intended to protect the ow center from
accidental over-pressurizaon. If the operator places the valves in the incorrect orientaon and starts the
ush cart, the uid from the ush cart will quickly ll and overow the NP tank.
3. Aach the ush cart hoses to the ush ports on the 3-way valves or ush ports on valve assembly.
4. Direct the uid toward the ground loop by rotang the three- way valves.
NOTE: Fluid should not enter the NPB tank during ushing. If it does, immediately stop the ush cart pump
and check to be sure the valves are in the correct orientaon.
WARNING: ONLY USE PREMIXED ANTIFREEZE IN A NON-FLAMMABLE STATE. FAILURE TO
OBSERVE SAFETY PRECAUTIONS MAY RESULT IN FIRE, INJURY, OR DEATH.
5. Flush/purge the ground loop using a high quality ush cart (see Figure 13). Add anfreeze as required.
6. Turn o ush cart. DO NOT PRESSURIZE GROUND LOOP.
7. Disconnect the ush cart hose from the right side of the ow center, and reconnect it to the le side as
shown below in Figure 14.
Figure 14: Flushing external headers- heat pump side
Discharge
Iso.
Valve
Sucon
Iso.
Valve

NPB Series Non-Pressurized Flow Centers | 10
8. Open the pump discharge isolaon valve on the NPB and ush the heat pump piping with the ush cart
(ensure sucon isolaon valve is closed). Note that you should start with the ush cart dead-head/return
valve closed due to the high ow rate. Open this valve slowly to purge air from the heat pump and associ-
ated piping.
9. Slowly open the sucon side isolaon valve on the NPB (boom le valve). This will allow uid to ll the
NPB reservoir with clean, debris free loop uid. The tank should be lled to about 1”-2” below the boom
of the tank’s neck. Figure 15 shows a cross secon of the NP ow center indicang the approximate uid
Figure 15: Fluid level of the NP tank
(shading)
Return pipe
Tank neck
1 to 2”
level. Close the discharge isolaon valve.
10. Turn o the ush cart. DO NOT PRESSURIZE the NPB. Close the
NPB discharge isolaon valve.
11. Disconnect the ush cart hose and replace the 1” plug on the
NPB.
12. Proceed to Start Up secon of IOM.

11 | Installaon, Operang, and Maintenance Manual
CLOSECLOSE
FLUID SUPPLYFLUID SUPPLY
1. Wire the circulator pump(s) to a control switch to allow the pump to be powered on and o as needed dur-
ing the ushing process (see Figure 21).
2. Remove the cap from the NPB tank.
3. Close the NPB sucon side isolaon valve (lower le side) and heat pump isolaon valves (if present) to
direct uid ow to the loop circuits.
4. Close all loop circuit valves except Circuit 1.
5. Aach supply hose to the NPB.
6. Direct uid into Circuit #1 unl uid returns to the NPB tank.
Many contractors employ non-pressurized ow centers and internal headers to ush the ground loop when a
ush cart is not available. Ball valves must be installed on each circuit to allow the ow center pump to ush
one circuit at a me. Not all loops may be ushed in this manner, especially those with larger than 3/4” PE
circuit piping. The contractor is responsible for ensuring that the NPB pumps can achieve the 2 feet/second
velocity required to purge air from the loop.
WARNING: OPEN THE MAIN POWER SUPPLY DISCONNECT SWITCH AND SECURE IT IN AN OPEN
POSITION PRIOR TO PERFORMING ELECTRICAL WORK. VERIFY THAT POWER HAS BEEN DISCON-
NECTED PRIOR TO WIRING THE PUMP(S). FAILING TO SECURE THE ELECTRICAL SUPPLY COULD
RESULT IN SERIOUS INJURY OR DEATH.
Figure 16: Flushing internal headers
Flushing with Inside Headers

NPB Series Non-Pressurized Flow Centers | 12
7. Close Circuit #1 and repeat for the remaining circuits.
8. Aer the nal circuit has been lled open the bypass valves to allow the heat pump piping to ll.
9. Close the NPB discharge valve and open the NPB sucon valve. Allow uid to push through the pumps and
ll the tank.
10. When the tank is lled with a few inches of the top, close the NPB sucon valve (lower le) while leaving
the supply uid on. This will pressurize the pump stack only.
11. Open the vent screw in the center of the UP(S)26 series pump motor with a large at head screwdriver al-
lowing a few drops of uid to drip out. Then, reghten the vent screw. Turn o the uid supply.
NOTE: Step #11 is crical. Opening the vent screw and allowing uid to drip out ensures that all trapped
air has exited the pump motor. Skipping this important step could lead to premature pump failure.
12. Remove the supply hose from the NPB and replace the 1” plug. Place the hose into the top of the NPB.
13. Open Circuit #1 isolaon valves (all others should be closed).
14. Close the NPB return valve and open the NPB sucon valve.
15. Energize the pump(s). Slowly open the NPB return valve This allows uid from the tank to be pumped to
the loop circuit. Air will be discharged into the tank as it is pushed from the loop. Monitor the uid level in
the tank and open the supply to add addional uid as needed to prevent the tank from being completely
emped.
NOTE: The pump(s) may push uid much more quickly than can be supplied by most domesc water
supply sources. Therefore, it is possible for the tank to empty very quickly. Use the NPB return valve
to balance the uid level in the tank with the uid supply. Once the uid level in the tank is stable, the
supply can be shut o and the return valve should be fully opened.
16. When the uid level in tank remains constant, close the supply and open the NPB return valve fully. This
directs the full uid ow to the loop circuit.
NOTE: Any air in the loop is compressed when the pump(s) is running. Therefore, if air is in the loop and the
pump is de-energized the air will expand pushing uid back into the tank which can cause it to overow. The
pump should only be de-energized when the loop circuit is completely purged of air.
17. Close the Circuit #1 ball valve and de-energize the pump(s).
18. Repeat steps 7 through 17 to purge each individual circuit and the heat pump.

13 | Installaon, Operang, and Maintenance Manual
19. Aer each circuit has been ushed individually, open all circuits and allow the pump(s) to run at full speed.
Dead-head the pump by closing the NPB return valve while monitoring the uid level in the tank to be sure
all air has been purged. If the uid level drops more than one to two inches, air remains in the loop and
purging must connue. Repeat steps 7 through 17 as needed.
Note: The dead-head process can be completed on each individual circuit.
20. De-energize the pump. The uid in the tank should only rise slightly. If the tank overows there is air in the
loop and purging must connue. It may be necessary to repeat the process of isolang and purging each
individual circuit.
21. Add anfreeze to the loop, if necessary.
22. Proceed to Start Up secon of this document.
Start-Up
1. Rotate NPB ow center valves to the correct operang posions.
2. Open the vent screw in the center of the pump motor with a large at head screwdriver allowing a few
drops of uid to drip out. Then, reghten the vent screw.
NOTE: Opening the vent screw and allowing uid to drip out ensures that all trapped air has exited the pump
motor. Skipping this important step could lead to premature pump failure.
3. Start ow center pump(s) and allow system to operate for several minutes. Remove tank’s cap and check
uid level adding addional loop uid, if necessary, while pump(s) are running. Fluid should be about 2”
below the boom of the tank’s neck as shown in Figure 15. Replace the cap and ghten unl there is an
audible “click” similar to an automobile’s gas cap.
4. Measure and record the ow rate using one of the methods described in the following secon of this
document. If using a NPB1A or NPB2A with three speed pumps, the ow can be adjusted by changing the
pump(s) speed. The ow rate should be within the range suggested by the heat pump manufacturer.
5. Verify the performance of the heat pump per the manufacturer’s literature by calculang the heat of
extracon and/or rejecon (HE-HR). The Geo-Flo website has a free calculator to assist in this calculaon.
Go to www.geo-o.com, select Design Calculators then HE-HR Calculator. The HE-HR should be within the
range specied by the heat pump manufacturer.
6. Geo-Flo recommends removing NPB isolaon valve handles to prevent accidental actuaon, and prevent
condensaon formaon.

Valve Open
Valve
Closed
From
Loop
NPB Series Non-Pressurized Flow Centers | 14
Measuring System Flow Rate
The system ow rate can be determined using two dierent methods as
described below.
Method 1: Flow rate from pressure drop
1. Measure the pressure drop across the heat pump’s heat exchanger via
the PT ports located at the water connecons of the unit (Figure 17).
Use a single large dial face pressure gauge to allow for more precise
measurement.
2. Determine the ow rate using the manufacturer’s published tables for
pressure drop versus ow (Figure 18). If the pressure drop is o the
manufacturer’s chart, the ow rate can be determined using a free on-
line calculator available on Geo-Flo’s website. Go to www.geo-o.com,
select Design Calculators then Flow Rate Calculator.
Method 2: Direct measurement using a Geo-Meter
NOTE: This method requires an addional eld installed tee assembly on
the return side of the NPB.
1. Aach the Geo-Meter to the tee assembly using a Flo-Link double O-ring
x 1” CAM ng and direct the exible hose into the top of the tank
(Figure 19).
2. Energize the pump(s).
3. Close the NPB return valve. This directs the uid through the Geo-Meter.
Be sure the Geo-Meter is vercal.
4. Read the ow rate*.
Figure 17: Measuring
pressure drop
WPD
PSI FT
3.0 0.9 2.2
4.5 1.8 4.2
6.0 2.9 6.8
3.0 0.9 2.1
4.5 1.7 4.0
6.0 2.8 6.6
3.0 0.9 2.0
4.5 1.7 3.9
6.0 2.8 6.4
3.0 0.9 2.0
4.5 1.6 3.8
6.0 2.7 6.2
20
EWT
°F Flow gpm
50
40
30
Figure 18: Example of heat
pump manufacturer’s table of
pressure drop versus ow rate
Example Only
Figure 19: Measuring with Geo-Meter
*Note: Flow meter is
calibrated for pure water.
Anfreeze mixtures have
dierent densies and will
impact the reading

15 | Installaon, Operang, and Maintenance Manual
Maintenance
There is no regularly scheduled maintenance required for the NP Series ow center. However, the uid level
in the tank should be monitored, parcularly during the rst several days aer installaon or service has been
performed.
Replacing Circulator Pump
WARNING: OPEN THE MAIN POWER SUPPLY DISCONNECT SWITCH AND SECURE IT IN AN OPEN
POSITION PRIOR TO PERFORMING ELECTRICAL WORK. VERIFY THAT POWER HAS BEEN DISCON-
NECTED PRIOR TO WIRING THE PUMP(S). FAILING TO SECURE THE ELECTRICAL SUPPLY COULD
RESULT IN SERIOUS INJURY OR DEATH.
1. Determine whether the circulator pump needs to be replaced. The pump motor should only be replaced af-
ter successfully troubleshoong the system and determining that the pump is not funconing. See Trouble-
shoong secon of this document for more informaon.
2. Close the NPB sucon and discharge valves.
3. Verify that power has been disconnected from the circulator pump(s) using a mulmeter.
4. Disconnect wiring from pump.
NOTE: Use a towel to catch the small amount of uid that exits the pump stack during motor removal.
5. Remove screws holding pump motor to pump housing (volute), and remove the pump motor.
6. Inspect the pump motor and volute for signs that indicate the mode of failure. For example, if debris is
present in the pump or volute the ground loop should be re-ushed with a quality ush cart equipped with
a lter.
7. Clean the pump seat on the pump housing (volute) with a cloth to remove any debris so that the gasket on
the pump will seal properly. Install the new pump motor and reconnect wiring.
8. Fill the tank as needed.
9. Open the NPB discharge and sucon valves. Remove the 1” plug on the unused discharge port. This allows
air to escape upward and allows uid to ll the pump stack. Replace the 1” plug when the uid has lled
the stack.
10. Open the vent screw in the center of the pump motor just installed with a large at head screwdriver allow-
ing a few drops of uid to drip out. Then, reghten the vent screw.

NPB Series Non-Pressurized Flow Centers | 16
NOTE: This step is crical. Opening the vent screw and allowing uid to drip out ensures that all trapped air
has exited the pump motor. Skipping this important step could lead to premature pump failure.
11. Energize the pump.
12. Verify system performance by checking the ow rate and temperature dierenal, and comparing the
values to the heat pump manufacturer’s published data. If installing a UPS26-99, be sure to set the pump
speed that provides a ow rate within the manufacturer’s recommend range.
13. Remove the tank’s cap and check the uid level. Fluid should be about 2” below the boom of the tank’s
neck as shown in Figure 15. Replace the cap and ghten unl there is an audible “click” similar to an auto-
mobile’s gas cap.
Converng NPB1 to NPB2
Follow procedure for Replacing Circulator Pump except remove the blank plate instead of the pump motor. Be
sure to remove the gasket (Figure 20).
Checking an-freeze/freeze protecon level
The loop uid may contain anfreeze at concentraon high enough to achieve a freeze protecon level that is
generally 10 degrees lower than the lowest expected entering uid temperature (EWT) to the heat pump. An-
freeze will be used when the loop uid entering the heat pump (EWT) is expected to drop below 40 degrees F.
The freeze protecon level depends on the type and concentraon of anfreeze.
Gasket
Figure 20: Removing cover plate
Cover Plate
Rubber Cover
Loop uid can be removed from the NPB ow center through one of
the three way valves (if installed) or through the top of the tank. The
specic gravity of the uid can then be measured with an appropri-
ate specic gravity hydrometer. The specic gravity is used to deter-
mine the percentage concentraon of anfreeze which is then used
to determine the freeze protecon level. The Residenal Pressure
Drop calculator available at www.geo-o.com provides informaon
on percent anfreeze, freeze protecon level, and specic gravity for
ethanol, methanol, and propylene glycol.

17 | Installaon, Operang, and Maintenance Manual
Pump High Voltage Wiring
WARNING: OPEN THE MAIN POWER SUPPLY DISCONNECT SWITCH AND SECURE IT IN AN OPEN
POSITION PRIOR TO PERFORMING ELECTRICAL WORK. VERIFY THAT POWER HAS BEEN DISCON-
NECTED PRIOR TO WIRING THE PUMP(S). FAILING TO SECURE THE ELECTRICAL SUPPLY COULD
RESULT IN SERIOUS INJURY OR DEATH.
Wire the circulator pump(s) to the heat pump as shown in Figure 21 (constant speed pumps). Follow all electri-
cal and local codes for wiring and fuse/breaker sizing.
From heat pump #1
fused/circuit breaker
protected pump
connections
N
L
Ground
L2
L1
N
L
Wiring for
NPD3and NPD4
(2nd pump on
LH side)
N
L
N
L
Wiring for
NPD4 (2nd pump
on RH side)
From heat pump #2
fused/circuit breaker
protected pump
connections
Pump #3 Pump #4
Pump #1 Pump #2
Capacitor
Speed Switch
Terminal Strip
Ground
L2
L1
From heat pump
fused/circuit breaker
protected pump
connections
Ground
L2
L1 N
L
N
L
Pump #2
Pump #1
Speed Switch
Terminal Strip
From heat pump #1
fused/circuit breaker
protected pump
connections
Ground
L2
L1
Wiring for
NPD3and NPD4
(2nd pump on
LH side)
L2
L1
L2
L1
L2
L1
L2
L1
Wiring for
NPD4 (2nd pump
on RH side)
From heat pump #2
fused/circuit breaker
protected pump
connections
Pump #3 Pump #4
Pump #1 Pump #2
Capacitor
Ground
L2
L1
L2
L1
Figure 21: Pump eld wiring. Top picture shows UPS26-99
control box; boom picture shows UP26-116 control box.