Bell & Gossett 210668B Z-4M User Manual

LISTED

INSTRUCTION MANUAL

210668B

Bell & Gossett®ZoneTrol II

Models Z-4B, Z-4M, Z-6B, Z-6M,
ZV-4B, ZV-4M, ZV-6B, ZV-6M

McDonnell & Miller ZoneSmart

U

L

®

C US

INSTALLER: PLEASE LEAVE THIS MANUAL FOR THE OWNER’S USE.

SAFETY
INSTRUCTION

This safety alert symbol will be used in this manual and on the
unit safety instructions decal to draw attention to safety related
instructions. When used, the safety alert symbol means ATTEN-

TION! BECOME ALERT! YOUR SAFETY IS INVOLVED!
FAILURE T
IN A SAFETY HAZARD.

NOTICE: This instruction manual is a supplement to, not a
replacement for Instruction Manual 210667. If you do
not have all manuals necessary for installation, please
contact the point of purchase or download the necessary
manuals at www.bellgossett.com.

O FOLLOW THE INSTRUCTIONS MAY RESULT

Models ZS-4B, ZS-4M, ZS-6B, ZS-6M,
ZSV-4B, ZSV-4M, ZSV-6B, ZSV-6M

™

™

Sensors Included

The Outdoor Temperature Sensor includes a
10 kΩ thermistor which provides an accurate
measurement of the outdoor temperature. The
sensor is protected by a white U.V. resistant
PVC plastic enclosure.

The Water Temperature Sensors have a zinc
sleeve for fast response and a wide operating
range. The sensors are supplied with 10 inches
(250mm) of two conductor wire.

DESCRIPTION

The outdoor reset modules are integrated into the
McDonnell & Miller ZoneSmart or Bell & Gossett ZoneTrol II
zone controllers. By monitoring outdoor temperature and
indexing the system supply water to the varying heatloss of
the building, the reset controllers minimize fuel consumption
while maximizing occupant comfort.

The Boiler Reset Control is designed to control a single
stage, non modulating heat source in order to provide outdoor
reset.

The Mix Reset Control is designed to control the supply water
temperature to a hydronic system in order to provide outdoor
reset or setpoint operation. The control uses a variable speed
injection pump to regulate the supply water temperature, while
protecting the boiler against flue gas condensation.

SENSOR INSTALLATION INSTRUCTIONS

Outdoor Air Temperature Sensor

• Remove the screw and pull the front cover off the sensor
enclosure.

• The sensor can either be mounted directly onto a wall or a
2" x 4" electrical box.

• When the sensor is wall mounted, the wiring should enter
through the back or bottom of the enclosure. Do not mount
the sensor with the conduit knockout facing upwards as
water could enter the enclosure and damage the sensor.

• In order to prevent heat transmitted through the wall from
affecting the sensor reading, it may be necessary to install
an insulating barrier behind the enclosure.

• The sensor should be mounted on a wall which best repre­sents the heat load on the building (a northern wall for most
buildings and a southern facing wall for buildings with large
sout h f aci ng gla ss areas). The sensor should not be
exposed to heat sources such as ventilation or window
openings.

• The sensor should be installed at an elevation above the

Boiler supply
sensor

BOIL OUT

SUP

COM

Boiler Temp.

Sensor

Sensor

Temp. Sensor

Outdoor Temp.

Mix Supply

SYS/
BLR.

N

INJ/

MIX

120 VAC

To system

pump (if
applicable)
1/3 max.
HP*

To
injector
pump (if

applicable)

1.1A max.

ground that will prevent accidental damage or tampering.

• Connect 18 AWG or similar wire to the two terminals pro­vided in the enclosure and run the wires from the sensor to
the control as shown in Figure 2. Do not run the wires paral­lel to telephone or power cables. If the sensor wires are
located in an area with strong sources of electromagnetic
interference (EMI), shielded cable or twisted pair should be

sed or the wires can be run in a grounded metal conduit. If

u
using shielded cable, the shield wire should be connected
to the Com Sen terminal on the control and not to earth
ground.

Replace the front cover of the sensor enclosure.

•

Water Temperature Sensor

• Water temperature sensors should be located as shown in
Figures 1 (boiler reset) & 3 (mix reset).

• Sensor wiring is per Figure 2.

• The Water Temperature Sensor can be strapped directly to
the pipe using the cable tie provided. Insulation should be
placed around the sensor to reduce the effect of air currents
on the sensor measurement.

• The Water Temperature Sensor should be placed down­stream of a pump or after an elbow or similar fitting. This is
especially important if large diameter pipes are used as the
thermal stratification within the pipe can result in erroneous
sensor readings. Proper sensor location requires that the
fluid is thoroughly mixed within the pipe before it reaches
the sensor.

than the BOIL MIN setting while the boiler is firing, the con­troller reduces the output to the variable speed injection
pump. This limits the amount of cool return water to the boiler,
and allows the boiler temperature to recover.

Exercise: The controller has a built-in exercising function. If
the pump has not been operated at least once every 3 days,
the control turns on the output for 10 seconds. This minimizes
the possibility of the pump seizing during a long period of

nactivity.

i

Warm Weather Shutdown (WWSD)

When the outdoor air temperature rises above the WWSD set­ting, the controller turns on the WWSD segment in the display.
When the control is in Warm Weather Shut Down, the Mixing
Demand pointer is displayed, if there is a demand. However,
the control does not operate the heating system to satisfy this
demand.

Figure 1: Sensor Location for Boiler Reset

OPERATING SEQUENCE

Boiler Reset Control

The Boiler Reset Control operates a single on / off heat source
to control the supply water temperature to a hydronic system.
The supply water temperature is based on the current outdoor
air temperature and the Characterized Heating Curve settings.

Outdoor Reset: The controller calculates a supply tempera­ture based on the current outdoor air temperature and the
Characterized Heating Curve settings. The burner on the boiler
is then cycled to maintain the water temperature required
based on the heating curve.

Warm Weather Shutdown: When the outdoor air temperature
rises above the WWSD setting, the controller turns on the
WWSD segment in the display. When the control is in Warm
Weather Shut Down, the Boiler Demand pointer is displayed, if
there is a demand. However, the control does not operate the
heating system to satisfy this demand.

Mix Reset Control

The Mix Reset Control uses a variable speed injection pump
to control the supply water temperature to a hydronic system.
The supply water temperature is based on either the current
outdoor temperature, or a fixed setpoint.

Outdoor Reset: The controller calculates a mixing supply
temperature based on the current outdoor air temperature and
the Characterized Heating Curve settings.

Variable Speed Injection: circulator is connected to the con­troller. The controller increases or decreases the power output
to a standard wet rotor circulator when there is a mixing
demand. The circulator speed varies to maintain the correct
mixed supply water temperature at the mix sensor. A visual
indication of the current variable speed output is displayed in
the LCD in the form of a horizontal bar graph.

Boiler Protection (BOIL MIN): The controller is capable of
providing boiler protection from cold mixing system return
water temperatures. If the boiler sensor temperature is cooler

Figure 2: Sensor and Mix Pump Wiring

Figure 3: Pump Terminology and Sensor Location

on systems using Mix or Injection Pump

*Do not exceed the maximum combined load.