Hydro-Temp VVV - Page 37

Installation Manual 5.1.2
37
A zone set to 0.5% will never start the system if it’s the
only zone calling. It could however combine with
another zone to start the system. For example two
zones calling for .5% could start the compressor at 1%.
Default settings from the factory are:
Zone 1 – 100%
Zone 2 – 75%
Zone 3 – 50%
Zone 4 – 25%
11.1.2 Allowed T-stat SP Adjust
This setting limits the amount the ZS zone thermostats
can be adjusted up or down. The default setting is 20
degrees.
11.1.3 Zone Alternate / Percentage
This installer setting typically needs no adjustment. This
setting is used to handle a situation where one zone is
calling for heat and one zone is calling for cool. This
setting defines how long the system will run in each
mode and the minimum speed the compressor will run
when a coinciding heat and cool call occurs. The factory
default for this setting is “45.20”. The controller breaks
this setting down as “time.percentage”. Time between
modes and minimum percentage to run compressor.
For example using the factory default setting, if a heat
call is being initiated by zone 1 and the compressor is
running at 2%, then zone 2 makes a cooling call at 1%
the zone alternate timer will start and the compressor
will ramp up to 20 percent. Zone 1’s damper will
remain open and all other dampers will remain closed.
The system will run like this for 45 minutes or until zone
1 is satisfied. Then the system will switch to cool, open
zone 2’s damper, close zone 1’s damper and remain at
20% compressor speed. The system will remain in cool
until zone 2 is satisfied or for a maximum of 45 minutes.
Then it could potentially switch back to heat for zone 1
and start the process again. Twenty percent in the
example above is the factory default. If the calculated
compressor speed required by the zone were to increase
above 20% the system would have ran at the calculated
speed when that zone was getting conditioned. This
setting (Twenty percent) is the minimum.
This routine provides heating and cooling to all zones as
needed in a precise way. The compressor percentage is
increased to try and satisfy the zone calling so it can
switch to the next mode. The actual compressor
percentage the compressor will run will never exceed
the Zone limit set for that zone.
11.1.4 Total System limit
Total system limit restricts the maximum system
output. This limit will take priority over the zone
limiting and if set lower than DWH or AHW stages will
affect the hot water output. The factory default setting
is 100%. You can use the following chart to convert
percentage to system tonnage.
Percentage
Comp
HZ
2.5 Ton
VStar
Output
Tonnage
4.0 Ton
VStar
Output
Tonnage
6 Ton
VStar
Output
Tonnage
1
40
.70
1.10
1.80
5
46
.77
1.22
1.98
10
52
.86
1.37
2.21
15
58
.95
1.52
2.44
20
64
1.05
1.68
2.66
25
70
1.14
1.83
2.89
30
76
1.23
1.98
3.12
35
82
1.32
2.13
3.35
40
88
1.41
2.28
3.57
45
94
1.50
2.43
3.80
50
100
1.59
2.58
4.03
55
106
1.68
2.74
4.25
60
112
1.77
2.89
4.48
65
118
1.86
3.04
4.71
70
124
1.95
3.19
4.94
75
130
2.05
3.34
5.16
80
136
2.14
3.49
5.39
85
142
2.23
3.65
5.62
90
148
2.32
3.80
5.85
95
154
2.41
3.95
6.07
100
160
2.5
4.10
6.30
11.1.5 Discharge air target temperature
Two settings make up the discharge air target
temperature. Discharge air target temperature in heat
and discharge air target temperature in cool. The
factory default settings are Heat 100ºF and cool 55ºF.
These targets are achieved by regulating the blower.
For example, a heating or cooling call will start the
blower at a rate of 400 CFM per ton in heat or 375 CFM
per ton in cool. After the system runs for a few minutes
the blower will start to modulate as needed to achieve
the discharge air temp. By factory default the blower