Electronic Thermostat Installation - Bosch FHP EC Large Series Installation, Operation And Maintenance Manual

EC Series
ELECTRONIC THERMOSTAT
INSTALLATION
Position the thermostat subbase against the wall
so that it is level and the thermostat wires
protrude through the middle of the subbase. Mark
the position of the subbase mounting holes and
drill holes with a 3/16-inch bit. Install supplied
anchors and secure base to the wall. Thermostat
wire must be 8-conductor, 18-AWG wire. Strip the
wires back 1/4-inch (longer strip lengths may
cause shorts) and insert the thermostat wires into
the connector as shown. Tighten the screws to
ensure secure connections. The thermostat has
the same type connectors, requiring the same
wiring. See instructions in the thermostat for
detailed installation and operation information
R
24VAC (Hot)
C
24VAC (Common)
Y1
Compressor (1st Stage)
Y2
Compressor (2nd Stage)
w
Auxiliary Heat
O
Reversing Valve
G
Blower Relay
L
System Monitor
Figure # 12 Thermostat Wiring
NOTE: When using a 2-cool, 3-heat thermostat
W1 and W2/EM must be connected together via
a jumper. (Figure#16)
THERMOSTAT
R
G
Y
C
O
B
E
W2
Figure # 13
EC Series
WATER QUALITY
Maintaining proper water quality is important for
insuring a long and trouble free service life for an
LV series heat pump.
For closed loop and boiler/tower systems water
chemistry can be checked and easily maintained to
insure that corrosive elements, dissolved oxygen
and pH levels are kept in check. It is important to
insure that any additive, antifreeze or corrosion
inhibitor that is added to the water loop is
compliant with all applicable laws and regulations
and is compatible with copper, brass and bronze
alloys. Insure that all recommended safety
precautions are followed when handling or adding
chemicals to the water loop.
For open loop systems, water quality is very
important. Refer to Quality Table on page# 6
shows acceptable ranges for a variety of water
quality factors. The three main concerns in open
loop installations are scaling, corrosion and
fouling.
In installations with hard water, scaling due to a
buildup of carbonates on the heat exchanger wall
can gradually degrade the heat pump performance
over time. Heat pumps that are affected by scaling
may exhibit low suction pressures in heating and
high head pressures in cooling with a gradual loss
of capacity and efficiency. Scaled heat exchangers
can be cleaned by a qualified technician but care
PACKAGED
HEAT PUMP
should be taken to avoid scaling in the first place.
R To limit scaling, water flow rates should be kept at
3 gallons/minute per nominal cooling ton (a 10°F
G
temperature rise in cooling) and care should be
Y
taken to avoid air in the water lines from suction
C
side leaks. Cupro-nickel coils are generally
O
recommended.
B
In installations with high hydrogen sulfide, chlorine
W1
or ammonia, corrosion is a potential problem. In
W2
these installations a cupro-nickel heat exchanger is
recommended along with maintaining proper flow
and keeping air out of the system. If water quality
is outside of the values in water quality table, then
a closed loop is recommended.
Fouling due to iron bacteria can also pose
problems in some open loop installations. Iron
bacteria fouling can quickly degrade system
performance and plug heat exchangers.
Air in the water system will greatly accelerate the
fouling or corrosion process.

Electronic Thermostat Installation | 13

NOTE: Failure to insure proper water quality
and flow rates can shorten the life of the
heat pump and potentially void the unit
warranty.
T111970289 (2015/01)