Specifications

Manual 2100-317
Page 20
OPEN LOOP
(Well System Applications)
NOTE:
Unit shipped from factory with 27 PSIG low
pressure switch wired into control circuit for
open loop applications.
WATER CONNECTIONS
It is very important that an adequate supply of clean,
noncorrosive 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 closing Solenoid Valve
(6) with a 24 V coil 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 (7) 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 (5) installed upstream of constant flow valve (7)
to collect foreign material which would clog the flow
valve orifice.
The figure shows the use of shutoff valves (9) and (11),
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 us gate or ball valves as
shutoffs so as to minimize pressure drop.
Drain cock (8) and (10), and tees have been included to
permit acid cleaning the refrigerant-to-water coil should
such cleaning be required. See WATER CORROSION.
Drain cock (12) 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.
The pressure requirements put on the pump are directly
affected by the diameter of pipe being used, as well as, by
the water flow rate through the pipe. The worksheet
included in manual 2110-078 should guarantee that the
well pump has enough capacity. It should also ensure
that the piping is not undersized which would create too
much pressure due to friction loss. High pressure losses
due to undersized pipe will reduce efficiency and require
larger pumps and could also create water noise problems.
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.
.oNtraP
elbaliavA.niM
GISPerusserP
etaRwolF
MPG
700-3068)1(516
800-3068)1(518
010-3068)1(514
110-3068)1(515
910-3068)1(513