EWC Controls ULTRA-TALK 3000 Technical Bulletin page 16

ZONE WEIGHTING FEATURE
The HVAC system's momentary BTU capacity level, is determined by multiplying one or more zone
weight assignment values by the proportional (or fixed) thermostat demand value, coming from
each respective zone. If the PID loop is active, the UT3000 will "ramp" (boost) the HVAC system's
BTU capacity above the base sum of zone weight(s) multiplied by zone demand(s).
LIMIT SAS PID "N" = PID LOOP ACTIVE
The equation for calculating the "SYSTEM" Initial and Maximum demand when active zones are
calling is the following:
EXAMPLE 1 :
Assigned
Weight
Zone 1 = 70%
x
Zone 2 = 15%
x
Zone 3 = 15%
* Unless Thermostat(s) Demand Changes
EXAMPLE 2 :
Assigned
Weight
Zone 1 = 65%
Zone 2 = 35%
x
* Unless Thermostat(s) Demand Changes
UT 3000 SYSTEM HEAT/COOL STAGING SCALE
OFF
HP: Y1 (Heat or Cool)
0%
H/C: W1 (Heat) / Y1 (Cool)
10%
HP= HEAT PUMP SYSTEM
HC= HEAT/COOL SYSTEM
EWC Controls Inc. 385 Highway 33 Englishtown, NJ 07726 800-446-3110 FAX 732-446-5362 E-Mail- info@ewccontrols.com
Zone WEIGHT x Tstat DEMAND = (Initial System Demand)
Initial System Demand (x3) = (PID Loop System Demand)
Thermostat System
Demand Demand
*
30% (.30) 21%
=
*
100% (1.0) 15%
=
36%
Thermostat System
Demand Demand
*
30% (.30) 11%
=
51%
HC: Y2 & W2
Threshold
(Fixed)
100
Calculated
Initial Demand
36%
Calculated
Starting Demand
11%
HP: Y2 (Cool)
HP: Y2 (Heat)
85%
HP: W2
Threshold
(
Adjustable
65% - 99%
Max System
Demand
*
x3 100%
=
PID Loop
Boost Value
Max System
Demand
*
x3 33%
=
PID Loop
Boost Value
HP: W2 (Aux)
100%
)
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