Bard GV27S1-A Installation Instructions Manual - page 19
Manual
2100-510E
Page
19 of 38
GROUND WATER
(WELL SYSTEM APPLICATIONS)
NOTE:
Unit shipped from factory with 60 PSIG low
pressure switch wired into control circuit for open loop
applications.
WATER CONNECTIONS
It is very important that an adequate supply of clean, non-
corrosive water at the proper pressure be provided before
the installation is made. Insufficient water, in the heating
mode for example, will cause the low pressure switch to
trip, shutting down the heat pump. In assessing the
capacity of the water system, it is advisable that the
complete water system be evaluated to prevent possible
lack of water or water pressure at various household
fixtures whenever the heat pump turns on. All plumbing to
and from the unit is to be installed in accordance with local
plumbing codes. The use of plastic pipe, where
permissible, is recommended to prevent electrolytic
corrosion of the water pipe. Because of the relatively cold
temperatures encountered with well water, it is strongly
recommended that the water lines connecting the unit be
insulated to prevent water droplets form condensing on the
pipe surface.
Refer to piping, Figure 10. Slow open/close with
End
Switch (2)
, 24V, provides on/off control of the water flow
to the unit. Refer to the wiring diagram for correct hookup
of the valve solenoid coil.
Constant Flow Valve (3)
provides correct flow of water to
the unit regardless of variations in water pressure. Observe
the water flow direction indicated by the arrow on the side
of the valve body. Following is a table showing which
valve is the be installed with which heat pump.
Strainer (8)
installed upstream of
water coil inlet
to collect
foreign material which would clog the flow valve orifice.
The figure shows the use of
shutoff valves (4)
and
(5)
, on
the in and out water lines to permit isolation of the unit
from the plumbing system should future service work
require this. Globe valves should not be used as shutoff
valves because of the excessive pressure drop inherent in
the valve design. Instead use gate or ball valves as
shutoffs, so as to minimize pressure drop.
Hose bib (6)
and
(7)
, and tees should be included to permit
acid cleaning the refrigerant-to-water coil should such
cleaning be required. See WATER CORROSION.
Hose bib (1)
provides access to the system to check water
flow through the constant flow valve to insure adequate
water flow through the unit. A water meter is used to
check the water flow rate.
WELL PUMP SIZING
Strictly speaking, sizing the well pump is the responsibility
of the well drilling contractor. It is important, however,
that the HVAC contractor be familiar with the factors that
determine what size pump will be required. Rule of thumb
estimates will invariably lead to under or oversized well
pumps. Undersizing the pump will result in inadequate
water to the whole plumbing system, but with especially
bad results to the heat pump – NO HEAT / NO COOL
calls will result. Oversized pumps will short cycle and
could cause premature pump motor or switch failures.
The well pump must be capable of supplying enough water
and at an adequate pressure to meet competing demands of
water fixtures. The well pump must be sized in such a way
that three requirements are met:
1. Adequate flow rate in GPM.
2. Adequate pressure at the fixture.
3. Able to meet the above from the depth of the
well-feet of lift.
TABLE 8
CONSTANT FLOW VALVES
(1) The pressure drop through the constant flow valve
will vary depending on the available pressure
ahead of the valve. Unless minimum of 15 psig
is available
immediately
ahead of the valve, no
water will flow.
.
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