Shipping & Packing List

Package 1 of 1 contains the following:

• (1) Model LZP-2 Zone Control Panel
• (1) Model 88K38 Temperature Sensor
• (1) Installation Instructions
• (1) Owners Manual
• (1) Warranty Card

Required Components (ordered separately)

24 VAC Transformer – The size of the transformer needed is determined by the total power requirements for the control panel, thermostats and dampers. The control panel and thermostats together require 10VA. The dampers require 10VA each. The size of the transformer will depend on the greatest number of dampers that could be energized at any given time.

NOTE – When power closed/spring open dampers are used, at least one zone's dampers will not be energized during a call for heating or cooling.

Thermostats – single-stage, electronic, 24-volt heat/cool thermostats which include a "C" (24VAC common) terminal. Do not use mechanical or power robbing thermostats.

Dampers – 2 or 3-wire, 24-volt dampers required. 2-wire, power closed/spring open preferred.

TABLE 1 – TRANSFORMERS

FIGURE 1 – LENNOX® MODEL LZP-2 CONTROL PANEL LAYOUT

This diagram shows the layout of the LZP-2 control panel. It includes terminals for EQUIP (W, G, Y, RC, RH), ZONE 1 (Y, G, R, NO, NC, C, W), and ZONE 2 (Y, G, R, NO, NC, C, W). It also shows indicators for NORMAL FLASHING, (TIME DELAY OVERRIDE) T.D.O., FUSE - 3A, SPARE FUSE, 24V AC, DISCHARGE AIR SENSOR, GAS, ELECT., PURGE, NO PURGE, HT-160, 140, CL-45, and 40.

Application

• Two zones
• Single-stage electric or gas furnace
• Single-stage air conditioner
• Multi-stage equipment can be used provided that it stages on it's own internal controls
• Not applicable to heat pump systems

Features

• Adjustable high and low discharge air temperature limits
• ON/OFF duct air purge control
• LED indicators for outputs
• Time Delay Override
• 2 or 3-wire damper compatibility

Installation

Illustration shows a typical two zone control system with Zone 1 set to 70°F (21°C) and Zone 2 set to 65°F (18°C).

1. Install the control panel indoors only.
2. Do not install the control panel where the temperature will exceed 140°F or will drop below 32°F.
3. Do not install the control panel on foundation walls, HVAC equipment or duct system where moisture may condense on the enclosure.
4. Do not install the control panel in a room where it will be exposed to elevated humidity levels such as a laundry room.
5. Remove the cover. Replace the cover when installation is complete.
6. There are eight slots on the base of the enclosure (see Figure 2).
7. Use #8 screws (field supplied) to install the base.

FIGURE 2 – CONTROL PANEL AND ENCLOSURE BASE

This diagram shows the control panel and its enclosure base. The control panel features numerous terminals labeled EQUIP (W, G, Y, RC, RH), 24VAC, GAS, ELECT, PURGE, NO PURGE, HT-160, 140, CL-45, 40, ZONE 1 (Y, G, R, NO, NC, C, W), and ZONE 2 (Y, G, R, NO, NC, C, W). It also indicates the location of the Discharge Air Sensor (DAS) terminals, a spare fuse, main fuse, and TDO (Time Delay Override) button. The enclosure base shows (8) Mounting Slots.

Installation (continued)

4. Install and Wire the Discharge Air Temperature Sensor

The tip of the sensor must be located in a region of fully mixed supply of air before the take-offs (not in a dead air space) in order for the system to work correctly.

a. Wire discharge air temperature probe to control panel using thermostat wire. Note that the temperature sensor is not polarity sensitive.

b. Be sure that the tip of the sensor is located at least 15 inches downstream from the leaving air side of the evaporator in the discharge plenum, and 1/3 of the depth (D/3) of the plenum (D) from the front of the plenum (the front is the side with the furnace or CB access doors), and centered side to side. Move the adjustable bracket along the length of the discharge air sensor to achieve proper sensor tip location (tip of sensor to be located at W ÷ 2). The sensor can be inserted from any side of the plenum, as long as the tip of the sensor is in the correct position. See Figure 3.

FIGURE 3 – DISCHARGE AIR SENSOR LOCATION

This diagram illustrates the correct placement of the discharge air sensor in a duct plenum. It shows the plenum dimensions (D for depth, W for width) and indicates the sensor tip should be placed 15 inches downstream from the evaporator, at 1/3 of the plenum depth (D/3) from the front, and centered side-to-side (W ÷ 2).

IMPORTANT: The discharge air sensor is required. If a short or open circuit is detected between the Plenum Sensor terminals, the control panel will only respond to Zone 1 and the dampers will stay in the open position.

Installation (continued)

5. Install the required transformer selected from Table 1

DO NOT USE the HVAC equipment transformer to power the control panel. Refer to the instructions provided with the transformer.

18 AWG thermostat wire minimum recommended.

Sizing the Transformer:

The system requires approximately 10 VA for the control panel and thermostats and 10 VA for each damper. The size of the transformer will depend on the greatest number of dampers that could be energized at any given time (at least one zone's dampers will not be energized during a heating or cooling call when using power close, spring open dampers). The size of the transformer must not exceed 75VA. If the value is greater than 75VA, some dampers will need to be powered by a separate transformer – refer to Field Wiring Damper Diagram 2 on page 6.

For instance, if you have 3 dampers, then you would require 10VA for the system, 20VA (10VA X 2) for the dampers for a total of 30VA, so catalog number 10P17 would be an adequate transformer size at 40VA.

TABLE 1 – TRANSFORMERS

The transformers listed in this chart include a plate mount for a 4" square electrical box.

6. Install the thermostats.

Refer to the instructions provided with the thermostat. Any 24-volt electronic thermostat with a "C" (24 VAC common) terminal can be used. Power robbing thermostats can cause unintended operation – DO NOT use mechanical or power robbing thermostats. Table 2 lists the required terminals and recommended Lennox thermostats:

18 AWG thermostat wire minimum recommended.

TABLE 2 – THERMOSTAT REQUIREMENTS

7. Install the dampers.

Refer to the instructions provided with the damper.

18 AWG thermostat wire minimum recommended.

Bypass Damper Sizing

When fewer than the maximum number of zones are calling for heating or cooling, an excess volume of air is delivered, and because of the excess air, an excess amount of static pressure is produced as well. Zone systems often require a bypass duct to relieve this pressure. A properly sized barometric bypass damper must be installed in the bypass duct which is run between the supply and return air duct systems (see Figure 4). The barometric damper and the bypass duct must be sized to accommodate the excess static pressure from the supply duct.

The bypass tap in the return air duct must be at least 6 ft. from the furnace /air handler to ensure that the hot or cold air coming off of the plenum has time to mix with the return air before it passes through the air handler again. The provided discharge air sensor will prevent any damage to the equipment from overheating or coil freeze-up by interrupting the HVAC equipment.

The bypass damper and duct should be sized to handle the excess pressure created when the smallest zone is operating alone (worst case). To size the bypass damper, subtract the total air volume capacity of the smallest zone from the total air volume of the system.

Example:

Total System air volume: 2000 cfm
Air volume of smallest zone: 600 cfm
Bypass requirement: 2000 - 600 = 1400 cfm

In this example, the bypass duct should be sized to handle the 1400 cfm excess pressure created when only the smallest zone has a demand. For bypass damper air volume capacities, see Table 3.

TABLE 3

Refer to the parts and supplies catalog for information on available barometric bypass dampers.

FIGURE 4 – BYPASS DAMPER INSTALLATION

This diagram illustrates a typical bypass damper installation. It shows ZONE 1 THERMOSTAT and ZONE 1 DAMPER connected to ZONE 1. Similarly, ZONE 2 THERMOSTAT and ZONE 2 DAMPER are connected to ZONE 2. A BYPASS DAMPER is installed in a BYPASS DUCT that runs between the SUPPLY AIR and RETURN AIR ducts. The diagram also shows the HEATING/COOLING UNIT, DISCHARGE AIR SENSOR, TRANSFORMER FOR DAMPERS, PANEL AND THERMOSTATS, and the ZONE CONTROL PANEL. It notes that the bypass tap in the return air duct should be at least 6 ft. (1.8 m) from the heating/cooling unit.

IMPORTANT: Bypass duct should be mounted as far away from the heating cooling unit as possible to allow for a better mix of the bypass air with the return air.

Field Wiring

DIAGRAM 1 – FIELD WIRING

This diagram details the field wiring for the Lennox® Model LZP-2 Control Panel. It shows connections from the A/C UNIT (Y1, C), FURNACE (W1, Y1, G), and a 24 VAC TRANSFORMER (120 VAC, 24 VAC). It illustrates wiring to the control panel terminals (EQUIP, 24VAC, GAS, ELECT, PURGE, NO PURGE, HT-160, 140, CL-45, 40, DISCHARGE AIR SENSOR, ZONE 1, ZONE 2) and to ZONE 1 THERMOSTAT, ZONE 1 Damper, ZONE 2 THERMOSTAT, and ZONE 2 Damper. A note indicates a FIELD INSTALLED JUMPER REQUIRED FOR SINGLE TRANSFORMER SYSTEMS, connecting RC and RH at the HVAC Equipment outputs.

NOTE: DISCHARGE AIR SENSOR must be installed, or only calls from Zone 1 will be recognized, and dampers will not be energized.

DIAGRAM 2 – DAMPER WIRING WITH SEPARATE TRANSFORMER

This diagram shows an alternative wiring setup for dampers using a separate 24 VAC transformer. It illustrates connections from the TRANSFORMER (120 VAC, 24 VAC) to a 24 VAC SPST N.O. RELAY, and then to ZONE 1 (Y, G, R, NO, NC, C, W) and ZONE 2 (Y, G, R, NO, NC, C, W).

Pin Jumper Settings (see Figure 5)

This diagram shows the location and function of various jumpers on the control panel. The jumpers are for GAS/ELECT, PURGE/NO PURGE, HT-160/140, and CL-45/40 settings.

ELECTRIC/GAS:

If electric heat is to be used, move the jumper to the “ELECT” position. This will turn on the fan (G output terminal) with a heat call (W output terminal). If the jumper is in the “GAS” position, it is assumed that the heating equipment will control the fan operation.

NO PURGE / PURGE:

If the NO PURGE / PURGE jumper is moved to the “PURGE” purge position, the G terminal will remain energized for a one minute purge delay following the completion of a cooling call. If the jumper is moved to the “NO PURGE” position, the G terminal will de-energize immediately following the completion of a cooling call. The NO PURGE setting is designed for use with systems where the furnace or air handler has a built in fan purge. The NO PURGE damper hold time is longer than the PURGE setting due to the Lennox furnaces installer settable maximum blower off delay of 3 minutes. The following chart details the zone panel outputs and damper hold times when a heating or cooling call is satisfied:

DISCHARGE AIR SENSOR HT-140/160:

This jumper controls the temperature at which the heating equipment will cut out to prevent overheating. For a high limit temperature of 140°F, move the jumper to the "140" position. For a high limit temperature of 160°F, leave the jumper in the "160" position.

IMPORTANT: The temperature sensor is required. If a short or open circuit is detected between the Discharge Air Sensor (DAS) terminals, the control panel will only respond to Zone 1 and the dampers will not close.

DISCHARGE AIR SENSOR CL-45/40:

This jumper controls the temperature at which the cooling equipment will cut out to prevent freezing the indoor coil. For a low limit temperature of 45°F, leave the jumper in the “45” position. For a low limit temperature of 40°F, move the jumper to the “40” position. To maintain optimum operation, it is recommended to leave this setting at “45”.

Jumper Settings Chart

¹The G terminal will remain energized for 1 minute.

LEDs

POWER – Blinks during normal operation. Starts to blink approximately 6 seconds after power up.

G, Y and W – Lights when respective equipment outputs are energized. The W LED will flash if the heating high temperature limit has been reached. The Y LED will flash if the cooling low temperature limit has been reached.

ZONE 1 Damper and ZONE 2 Damper – Lights when the Normally Open (NO) damper terminal for that zone is energized (i.e. LEDs show which zones are NOT receiving conditioning when the HVAC equipment is operating).

Sequence of Operation

A Time Delay Override (TDO) button is available on the control panel to speed up the internal timer by a factor of 60 for system checkout. One second of holding down the button relates to one minute of speed up time in the control.

HEATING AND COOLING EQUIPMENT OPERATION

Heating Operation

When a zone makes a call for Heat, the W output terminal will energize. The G terminal will also energize if the ELECTRIC/GAS jumper is in the ELECT position. The W terminal de-energizes when (1) all zones stop calling for Heat, (2) the call has exceeded the heat/cool changeover time limit while a cooling call exists or (3) the call is interrupted by the high limit setting. When the W terminal is de-energized, a minimum off time delay of 4 minutes must elapse before it can be energized again.

Fan Purge Time Delay (Heating)

If the ELECTRIC/GAS jumper is in the ELECT position and the PURGE/NO PURGE jumper is in the PURGE position, the G terminal will remain energized for one minute after the W terminal is de-energized. The NO PURGE setting is the preferred purge control setting for Lennox equipment. Lennox equipment includes controls which sequence the indoor fan off after a call for heat has been satisfied.

If the ELECTRIC/GAS jumper is set in the GAS position, the G terminal does not turn on during purge regardless of the position of the PURGE or NO PURGE switch. Lennox furnaces will control the purge though the furnace control board cool down feature. The cool down time is often adjustable at the furnace control board up to 3.5 minutes. NO PURGE is the preferred method of purge when this zone panel is applied to Lennox equipment.

Cooling Operation

When a zone makes a call for Cooling, the Y and G terminals will energize. The Y terminal de-energizes when (1) all zones stop calling for Cooling, (2) the call has exceeded the heat/cool changeover time limit while a heat call exists or (3) the call is interrupted by the low limit temperature setting. When the Y terminal is de-energized, a minimum off time delay of 4 minutes must elapse before it can be energized again.

Fan Purge Time Delay (Cooling)

If the PURGE/NO PURGE jumper is in the PURGE position, the G terminal will remain energized for one minute after the Y terminal is de-energized. If the jumper is in the NO PURGE position, the G terminal will de-energize immediately.

Heat/Cool Changeover:

When a call for heating or cooling exists and an opposing call is made from another zone, a 20 minute timer is activated. If the original call is not satisfied within that 20-minute time period, the call will be interrupted, turning the equipment off and allowing for the normal fan purge cycle and minimum equipment off time. The opposing call will then be answered. After 20 minutes, if the original call still exists, the opposing call will be interrupted and the original call can once again be recognized.

High/Low Limit Temperature:

The high/low limit temperature settings are designed to prevent the heat exchanger from overheating or the cooling coil from freezing. The temperature sensor in the supply duct senses the discharge air temperature and interrupts the heating/cooling equipment (depending on the Heat and Cool temperatures set on the control panel) before overheating/freezing occurs. When a heating/cooling call is interrupted by the high/low temperature limit, the zone control panel turns the equipment off and energizes the G terminal (if not already energized). The W or Y LED on the control panel will flash during a high/low limit temperature interrupt. Once the temperature drops/rises 10°F and the minimum off time has expired, the equipment is turned back on if the call for conditioning still exists. The Heating/Cooling LED will stop flashing.

IMPORTANT: Should a short or open circuit be detected across the DAS terminals, the zone system will respond only to Zone 1 and the dampers will not energize.

Sequence of Operation (continued)

CONTINUOUS FAN OPERATION

A call for Fan from any zone will initiate the G equipment output terminal. The normally open (NO) damper terminal at all zones not calling for continuous fan will be energized.

DAMPER OPERATION

The "NO" output will be energized and the "NC” output will be de-energized for any zone not calling for heating or cooling while the equipment output is energized and during the damper purge time delay. During equipment operation or during the damper purge time delay, should all zones stop calling for heating or cooling, the damper terminals will remain in the position they were in before all zones stopped calling.

Damper Purge Time Delay

When the Purge/No Purge jumper is at No Purge, the damper purge time delay is 3.5 minutes and begins when the equipment output(s) turn off. NO PURGE is the preferred method of purge control for Lennox furnaces and air conditioners. When the jumper is at Purge, the damper purge time delay is one (1) minute.

Troubleshooting

DETECTING HVAC SYSTEM PROBLEMS

Troubleshooting (continued)

DETECTING HEATING, COOLING AND FAN PROBLEMS

Troubleshooting (continued)

DETECTING DAMPER PROBLEMS

CHECKING THERMOSTAT VOLTAGES

Using a digital voltmeter (DVM) measure the AC voltage supplied at the R and C terminals of the Thermostat inputs on the control panel for the zone in question. This voltage should be same as the voltage supplied to the control panel 24VAC terminals. Make a call for heat, cooling or fan. Measure the voltage across the terminal that should be energized (i.e. W for heat, Y for cooling, etc.) and the C terminal. This should be the same voltage as there is between the R and C terminals. Measure the voltage across a terminal that should NOT be energized and the C terminal; this voltage should be zero.

DISCHARGE AIR SENSOR CHECKOUT

The discharge air sensor is a temperature dependent resistor; the higher the temperature, the lower the resistance. In order to confirm the sensor is working, both sensor leads must be disconnected from the zone panel board. Using a digital voltmeter (DVM) set to read resistance, touch the leads from the sensor to the probes of the DVM. Take care not to create a parallel resistance path through your body by touching both probes with your fingers or a faulty reading will be obtained. At 77F, the resistance of the sensor will be 10K ohm. If the sensor is cooler than 77F, the resistance will be higher, if it is warmer, the resistance will be lower. After reading the resistance at room temperature, warm the tip of the sensor by holding it in the palm of your hand, and take another resistance reading. This reading should be noticeable lower than the room temperature reading.

Discharge Air Sensor Resistance Table

The zone panel is well equipped to monitor the operation of the probe and determine if a failure has occurred. The probe should be considered an integral (but replaceable) part of the zone panel. The zone panel will indicate if the probe is operating improperly and needs to be replaced.