EWC Controls ULTRA-TALK 3000 Technical Bulletin page 17

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 inactive, the UT3000 will not "ramp" the HVAC system's BTU
capacity above the base sum of zone weight(s) multiplied by zone demand(s).
LIMIT SAS PID "Y" = PID LOOP INACTIVE
The equation for calculating the "SYSTEM" starting and final demand when active zones are
calling is the following:
EXAMPLE 1 :
Assigned
Weight
Zone 1 = 70%
Zone 2 = 15%
Zone 3 = 15%
* Unless Thermostat(s) Demand Changes
EXAMPLE 2 :
Assigned
Weight
Zone 1 = 65%
Zone 2 = 35%
* Unless Thermostat(s) Demand Changes
UT 3000 SYSTEM HEAT/COOL STAGING SCALE
OFF
0%
H/C: W1 (Heat) / Y1 (Cool)
10%
HP= HEAT PUMP SYSTEM
HC= HEAT/COOL SYSTEM
17
EWC Controls Inc. 385 Highway 33 Englishtown, NJ 07726 800-446-3110 FAX 732-446-5362 E-Mail- info@ewccontrols.com
ZONE WEIGHTING FEATURE
Zone WEIGHT x Tstat DEMAND = (Initial System Demand)
Thermostat
Demand
*
30% (.30)
x
*
100% (1.0)
x
Thermostat
Demand
*
30% (.30)
x
HP: Y1 (Heat or Cool)
HC: Y2 & W2
100
System Calculated
Demand Initial Demand
21%
=
15%
=
36%
System Calculated
Demand Starting Demand
11%
=
HP: Y2 (Heat)
51%
Threshold
(Fixed)
Max System
36%
=
11%
=
HP: Y2 (Cool)
HP: W2 (Aux)
85%
HP: W2
Threshold
( )
Adjustable
65% - 99%
Demand
*
36%
Max System
Demand
*
11%
100%