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System Checkout; Unit Start-Up; Maintenance - Bosch LM Series Installation, Operation And Maintenance Manual

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LM Series Heat Pump


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
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
Unit is serviceable. Be certain that all access
panels are secured in place.
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.


1. Put the UPM board in "test" mode.
Revised 09-13
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
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
12. Set the thermostat to maintain the desired
space temperature.
13. Check for vibrations, leaks, etc.


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
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
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.
System Checkout | 21
8 733 905 315 (2013/9)

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