Bosch LM User Manual
System Checkout | 23LM Series Heat Pump
SYSTEM CHECKOUT
After completing the installation, and before
energizing the unit, the following system checks
should be made:
• Verify that the supply voltage to the heat pump
is in accordance with the nameplate ratings.
• Make sure that all electrical connections are
tight and secure.
• Check the electrical fusing and wiring for the
correct size.
Ensure cabinet and Electrical Box are
properly grounded.
• Verify that the low voltage wiring between the
thermostat and the unit is correct.
• Verify that the water piping is complete and
correct.
• Check that the water flow is correct, and
adjust if necessary.
• Check the blower for free rotation, and that it
is secured to the shaft.
• Verify that vibration isolation has been
provided.
• Unit is serviceable. Be certain that all access
panels are secured in place.
Considerations:
1. Always check incoming line voltage power
supply and secondary control voltage for
adequacy. Transformer primaries are dual
tapped for 208 and 230 volts. Connect the
appropriate tap to ensure a minimum of 18
volts secondary control voltage. 24 volts is
ideal for best operation.
2. Long length thermostat and control wiring
leads may create voltage drop. Increase wire
gauge or up-size transformers may be required
to insure minimum secondary voltage supply.
3. FHP recommends the following guidelines for
wiring between a thermostat and the unit: 18
GA up to 60 foot, 16 GA up to 100 ft and 14 GA
up to 140 ft.
4. Do not apply additional controlled devices to
the control circuit power supply without
consulting the factory. Doing so may void
equipment warranties.
5. Check with all code authorities on
requirements involving condensate disposal/
over flow protection criteria.
UNIT START-UP
1. Put the UPM board in “test” mode.
2. Set the thermostat to the highest setting.
3. Set the thermostat system switch to “COOL”,
and the fan switch to the “AUTO” position. The
reversing valve solenoid should energize. The
compressor and fan should not run.
4. Reduce the thermostat setting approximately 5
degrees below the room temperature.
5. Verify the heat pump is operating in the cooling
mode.
6. Turn the thermostat system switch to the
“OFF” position. The unit should stop running
and the reversing valve should de energize.
7. Leave the unit off for approximately (5)
minutes to allow for system equalization.
8. Turn the thermostat to the lowest setting.
9. Set the thermostat switch to “HEAT”.
10. Increase the thermostat setting approximately
5 degrees above the room temperature.
11. Verify the heat pump is operating in the heating
mode.
12. Set the thermostat to maintain the desired
space temperature.
13. Check for vibrations, leaks, etc.
MAINTENANCE
1. Filter changes or cleanings are required at
regular intervals. The time period between
filter changes will depend upon type of
environment the equipment is used in. In a
single family home, that is not under
construction, changing or cleaning the filter
every 60 days is sufficient. In other
applications such as motels, where daily
vacuuming produces a large amount of lint,
filter changes may need to be as frequent as
biweekly.
Equipment should never be used during
construction due to likelihood of wall board
dust accumulation in the air coil of the
equipment which permanently affects the
performance and may shorten the life of the
equipment.
2. An annual “checkup” is recommended by a
licensed refrigeration mechanic. Recording the
performance measurements of volts, amps,
and water temperature differences (both
heating and cooling) is recommended. This
data should be compared to the information on
the unit’s data plate and the data taken at the
original startup of the equipment.
8 733 905 315 (2014/07)Revised 07-14
24 | Maintenance LM Series Heat Pump
1) UP
2) AWAY
1) UP
2) AWAY
3. Lubrication of the blower motor is not
required, however may be performed on some
motors to extend motor life. Use SAE-20 nondetergent electric motor oil.
4. The condensate drain should be checked
annually by cleaning and flushing to insure
proper drainage.
5. Periodic lockouts almost always are caused by
air or water flow problems. The lockout
(shutdown) of the unit is a normal protective
measure in the design of the equipment. If
continual lockouts occur call a mechanic
immediately and have them check for: water
2. Remove and retain lower panel by removing
(3)three screws. (Figure #26)
Figure # 25
flow problems, water temperature problems,
air flow problems or air temperature problems.
Use of the pressure and temperature charts for
the unit may be required to properly determine
the cause.
Access to Internal Components for
Vertical (VT) Units
See LM IOM for further reference. Manual is
located inside of the unit.
1. Using a Flat screw driver remove and retain
Panel Belt by inserting the screwdriver into the
slot and releasing the catch. (Figures #24 and
#25)
Heat pumps are supplied with panel belt which
needs to be removed to access screws for panel
removal. The belt is held in place by a clip on
one side and an interference fit on the other end.
Figure # 24
Figure # 26
3. Remove and retain upper panel by lifting up
and out as shown in Figure #27
Figure # 27
4. Repeat steps 1–3 for other sides as necessary.
LM Series Heat Pump8 733 905 315 (2014/07) Subject to change without prior notice
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