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Freeze Protection
Depending on the ambient temperature the unit may be
exposed to freeze, there are multiple options for freeze
protection. They are listed in order of highest ambient
(least freeze protection) to the lowest ambient (most
Sound power levels
freeze protection).
For all Multi-Pipe units running with water under
Discharge
cold ambient temperature (below 0°C), it is extremely
important to keep full water flow in the Chilled/Hot Water
Measurement conditions:
for an extended time after last compressor stops. This
Measurements taken in a room adjacent to the room containing the FWD, at the outlet of the rectangular duct (1.5 m
will protect chilled/hot water exchanger from freezing
long) fixed to its discharge opening.
by refrigerant migration. This is why Chilled/Hot Water
Exchanger water pump output relay must be used
Fan
to control the water pumps. This is not mandatory if
Unit
speed
glycol is used with protection down to lowest ambient
1
FWD 08
2
expected.
3
1. Water pump and heaters
1
FWD 10
2
3
a.
Heaters are factory installed on brazed plates
1
exchangers. They will protect it from freezing in
FWD 12
2
ambient temperatures down to -18°C. Heaters are
3
installed on the water piping and on the pumps of
1
FWD 14
2
units equipped with hydraulic module.
3
b.
Install heat tape on all water piping, pumps, and
1
FWD 20
2
other components that may be damaged if exposed
3
to freezing temperatures. Heat pump must be
designed for low ambient temperature applications.
Intake
Heat tape selection should be based on the lowest
expected ambient temperature.
Measurement conditions:
c.
Tracer Symbio™ 800 controller can start the
Measurements taken at the horizontal air intake.
pump(s) when freezing conditions are detected. For
this option the pumps must be controlled by the
Fan
Unit
speed
CMAF unit and this function validated on the unit
1
controller.
FWD 08
2
a)
Water shut off valves need to stay open at all
3
1
times.
FWD 10
2
Note: Water pump control and heater combination will
3
1
protect the Chilled/Hot Water Exchanger down to any
FWD 12
2
ambient temperature if provided power is available
3
to the pump and the Tracer Symbio™ 800. This option
1
FWD 14
2
will NOT protect the exchangers in the event of power
3
failure to the unit unless backup power is supplied to the
1
necessary components.
FWD 20
2
3
2. Freeze inhibitor
a.
Freeze protection can be accomplished by adding
sufficient glycol to protect against freezing down to
the lowest ambient expected.
b.
See "Chilled / hot water exchanger glycol
requirement" section for guidance on determining
the glycol concentration.
Note: Use of glycol type antifreeze reduces the cooling
capacity of the unit and must be considered in the
design of the system specifications.
CAUTION! When using freeze inhibitor, never fill the
system with pure glycol.
CG-SVX051A-GB
UNT-PRC002-GB
Chilled/hot water freeze protection
Power level in dB(A), per Hz frequency band
125
250
55
50
57
54
58
57
57
51
58
54
60
58
57
51
58
54
60
58
56
62
61
66
63
69
57
63
61
66
63
69
Power level in dB(A), per Hz frequency band
125
250
56
55
63
62
66
65
62
58
66
63
70
67
62
58
66
63
70
67
66
65
73
72
78
76
68
72
76
76
78
79
OR
Always fill the system with diluted solution. Maximum
concentration of glycol is 40%. Higher glycol
concentration will damage pump seal.
3. Drain water circuit
For ambient temperatures below -20°C and for
installation not including either option 1 or 2 above
described.
a.
Shut off power supply to unit and to all heaters.
b.
Purge the water circuit
c.
Blow out the chilled/hot water exchanger to ensure
that no liquid is left inside the Chilled/Hot Water
500
1000
2000
42
37
37
Exchanger and the water lines. Drain the pump.
47
40
30
Note: It is not recommended to drain the water circuit for
50
42
32
45
42
34
the following reasons.
48
45
38
1.
The water circuit will rust and its lifetime could be
50
48
40
reduced.
45
42
34
48
45
38
2.
Water will remain in the bottom of the plate heat
50
48
40
exchangers and freeze damage could occur.
50
48
39
55
53
47
CAUTION! Chilled / hot water exchanger damage!
58
56
50
51
49
40
If insufficient concentration or no glycol is used, the
55
53
47
Chilled/Hot Water Exchanger water pumps must be
58
56
50
controlled by the Tracer Symbio™ 800 to avoid severe
damage to exchangers due to freezing. A power loss of
15 minutes during freezing can damage the exchangers.
It is the responsibility of the installing contractor and/
or the customer to ensure that a pump will start when
called upon by the unit controls. Please consult TRANE
service for unit setting and % of glycol required.
500
1000
2000
With factory-fitted disconnect switch option, exchanger
55
53
46
trace heating is taken from the live side of the isolator.
60
60
53
63
62
56
As a consequence, the heaters are energized as long as
55
58
51
the main switch is closed. Supply voltage to the heating
60
62
56
tapes is 400V.
63
65
59
55
58
51
•
Avoid the use of very low or near minimum
60
62
56
chilled fluid flow rates through the unit. Higher
63
65
59
velocity chilled fluid flow reduces freeze risk in all
65
65
57
69
71
64
situations.
73
75
69
•
Flow rates below limits have increased freeze
64
64
56
68
71
65
potential and have not been considered by freeze
71
74
69
protection algorithms.
•
Avoid applications and situations that result in
a requirement for rapid cycling or repeated starting
and stopping of the unit. Keep in mind that unit
control algorithms may prevent a rapid compressor
restart after shutting down when the chilled/hot
water exchanger has been operating near by or
below the LRTC (Low Refrigerant Temperature
Cutout) limit.
•
Maintain refrigerant charge at appropriate
levels. If charge is in question, contact Trane service.
A reduced or low level of charge can increase the
likelihood of freezing conditions in the chilled/hot
water exchanger and/or LRTC diagnostic shutdowns.
OR
Overall power
4000
8000
dB(A)
31
30
46
38
40
50
40
43
53
33
28
48
39
35
51
42
39
54
33
28
48
39
35
51
42
39
54
38
36
56
46
45
60
50
49
63
39
37
57
46
45
60
50
49
63
Overall power
4000
8000
dB(A)
45
42
57
53
53
64
55
57
67
48
44
61
55
52
66
59
57
69
48
44
61
55
52
66
59
57
69
50
46
68
59
57
74
64
63
78
52
50
69
61
61
75
66
66
78
11
43
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