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Installation - water loop, Loop water applications, Ground water applications (open loop) – Trane GSSD User Manual

Page 15: Ground water applications (closed loop)

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15

Loop Water Applications

It should be noted that there is no me-

chanical difference between geother-
mal (closed loop) and ground water

(open loop) GSSD units. Generally in

a closed loop application, there is a
percentage of antifreeze in the water.

In these applications, the 20 degree F

freezestat, along with the 7 psig safety
pressure switch may be used. All other

applications require the 35 degree F

freezestat, along with the 35 psig safe-
ty pressure switch.

Ground Water Applications
(Open Loop)

Where an existing or proposed well

can provide an ample supply of suit-

able quality water, open ground water
systems may be very efficient. How-

ever, there are several potential con-

siderations that should be addressed
prior to installation of an open loop

system:

!

A 60 mesh straining device must
be placed in the incoming water
line. The sand filter/separator
helps ensure clean water by
removing any particles in the
water.

Note: A filter/separator

should be available from your
local dealer.

!

Even if plenty of water is
available, there needs to be an
acceptable way to discharge it
after it has passed through the heat
pump. A three-ton heat pump is

apt to use one million gallons of
water per year. It may be
necessary to install a recharge well
to return the water to the aquifer.
In some soils, this may be difficult
to do.

!

Water quality must also be
acceptable to maintain the
integrity and life of the unit. The
loop fluid must have minimal
suspended solids, and must be
non-corrosive to copper or brass.
See Table 2 for specifications.

Ground Water Applications
(Closed Loop)

Loop sizing should be done by a qual-
ified installer to insure maximized unit

performance.
In areas where the ground water tem-

perature is 66 degrees F or less, the
earth coupling fluid requires at least a

15 percent by volume antifreeze solu-

tion. Using Table 3, calculate the ap-
proximate water volume of the

system. Add one gallon to your total as

an allowance for water in each heat
pump and connection hoses. Check

the earth coupling design for the anti-

freeze percentage required. MORE IS
NOT BETTER-Do no exceed the

amount indicated in the design specifi-

cations.

Use only FULL STRENGTH INHIB-
ITED PROPYLENE GLYCOL OR

METHANOL, not solutions which
have already been diluted.

Note:

The water quality of the fluid loop
should meet the same specifications
as in Table 2.

Table 2: Water Supply Requirements

Scaling

Calcium and
magnesium salts
(total hardness)

Less than 350 ppm

Corrosion

pH

7.5-9.5

Hydrogen Sulfide

Less than 1 ppm

Sulfates

Less than 25 ppm

Carbon dioxide

Less than 75 ppm

Chloride

Less than 125 ppm

Total dissolved solids
(TDS)

Less than 1000 ppm

Biological Growth

Iron bacteria

Low

Erosion

Suspended Solids

Low

Table 3: Water Volume

Volume in Gallons/100 Ft.

Pipe Size

3/4”

1”

1 1/4” 1 1/2”

2”

Volume
SDR-11

3.02 4.73 7.52 9.85

15.4

Volume
SCH 40

2.77 4.49 7.77 10.6

17.4

Installation - Water Loop