Bard I-TEC® ERV Economizer Ventilator System (Vent Code "E")

General Description

The I-TEC energy recovery ventilator (ERV) economizer ventilator system is designed to provide energy efficient, cost effective ventilation to meet IAQ (indoor air quality) requirements while still maintaining good indoor comfort and humidity control for a variety of applications such as schools, classrooms, lounges, conference rooms, and others. It provides a constant supply of fresh air for control of airborne pollutants including CO2, smoke, radon, formaldehyde, excess moisture, virus, and bacteria.

The ERV incorporates rotary heat exchanger technology to remove both heat and moisture. The package consists of unique rotary energy recovery cassettes that can be easily removed for cleaning or maintenance. It has two 15" diameter heat transfer wheels for efficient heat transfer. The heat transfer wheels use a permanently bonded dry desiccant coating for total heat recovery.

The I-TEC ERV is also provided with filters to reduce the required service needed and to extend the life of the heat recovery wheels. The exhaust air blower is protected by disposable filters, and the intake air blower is protected by washable filters. Both are accessible without the need for tools.

Ventilation is accomplished with two blower/motor assemblies for maximum ventilation at low sound levels. The intake and exhaust blowers can be independently adjusted to maintain desired building pressurization conditions. The rotating wheels provide the heat transfer effectively during both summer and winter conditions. Provides required ventilation to meet the requirements of ASHRAE 62.1 Standard.

NOTE: During operation below 5°F outdoor temperature, freezing of moisture in the heat transfer wheel can occur. Consult the factory if this possibility exists.

When the outdoor air is cool, the unit provides economizer operation by stopping the ERV wheels and allowing the cool air into the room when needed. The ERV economizer is designed to economize in cooling mode when the outdoor temperature is below the outdoor temperature sensor setpoint. This is factory set at 60°F. Above 60°F, economizer operation is inhibited. Economizer operation is also inhibited when in heating mode.

Economizer operation consists of disabling the ERV cassette wheels from operating, thus bringing in fresh air to the room and exhausting stale air. Since the ERV wheels are not turning, room heat is not recovered and is exhausted from the room. Bard Part #8403-060.

A programmable electronic thermostat must be used with this vent package because three stages of cooling are required.

Control Wiring

The I-TEC ERV comes wired from the factory ready to operate in manual mode (ON/OFF cycling) and set to 375 CFM of ventilation. Care must be taken when deciding how to control the operation of the ventilator. When designing the control circuit for the ventilator, the following requirements must be met:

1. The indoor blower must be run whenever the I-TEC ERV is run.
2. Select and configure the correct CFM ventilation level that the I-TEC ERV needs to operate and configure the system to this level following later instructions within this section. Over-ventilating serves no useful purpose and significantly affects the overall efficiency of the heat pump system. System operating costs would also increase.
3. Run the I-TEC ERV only during periods when the conditioned space is occupied. Running the ERV during unoccupied periods wastes energy, decreases the expected life of the ERV, and can result in large moisture buildup in the structure. The ERV removes 60-70% of the moisture in the incoming air, not 100% of it. Running the ERV when the structure is unoccupied allows moisture to build up in the structure because there is little or no cooling load. Thus, the air conditioner is not running enough to remove the excess moisture being brought in. Use a control system that in some way can control the system based upon occupancy.

Recommended Control Sequence

Use a programmable electronic thermostat with an auxiliary terminal to control the ERV based on daily programmed occupancy periods. Bard markets and recommends Bard Part #8403-060 programmable electronic thermostat.

NOTE: The thermostat must have three stages of cooling.

NOTE: The ventilation package comes with a blower interlock function, but it is disabled when it is shipped from the factory. In case a thermostat with an occupancy output or occupancy sensor is not utilized, the "A" terminal to "G" terminal must be tied to drive the ventilation package. If a thermostat or control does drive occupancy output, remove the tape from the orange wire located in the low voltage terminal box, and connect it to the “G” terminal to activate this function.

Changing Ventilation CFM Rates in Manual Mode

To adjust the airflow ventilation rate, first refer to Table 1 to look up the Flow Index needed for the intake and exhaust blowers for the CFM required. Then, perform the following steps:

1. Open front swinging doors of the main unit (by popping front door latches).
2. Throw the main power disconnect to the OFF position to eliminate the risk of injury or death due to electrical shock.
3. Remove five (5) screws holding the front ERV door in place (see Figure 1 on page 6).
4. Remove the ERV control panel cover by removing four (4) screws.
5. Locate two 0-10Vdc motor control boards in the control panel (see Figure 2 on page 7).
6. On the intake motor control board, observing the green status light, turn the manual adjust potentiometer counterclockwise to increase flow index or clockwise to reduce flow index to match the desired setting.

   NOTE: After a long pause, the green status light will blink long-blinks for the tens count of the flow rate index, then immediately followed by fast blinks which indicate the second digit. For example, a flow index of 23 would be two long blinks, followed by three fast blinks of the green status light.

7. On the exhaust motor control board, observing the green status light, turn the manual adjust potentiometer counterclockwise to increase flow index or clockwise to reduce flow index to match the desired setting.

   NOTE: Same green status light blink as Step #6.

Table 1: ERV "Manual Mode" Jumper Pin on "M" Terminal

To adjust the airflow ventilation rate (NO CO2 CONTROL/NON-MODULATING), determine the flow index needed for the intake and exhaust blowers for the required CFM. Use a small Phillips-head screwdriver to make adjustments.

Instructions for adjusting CFM using control boards:

1. Locate two (2) 0-10Vdc motor control boards in the control panel.
2. On the intake motor control board (RH side of control panel), observing the green status light, turn the manual adjust potentiometer counterclockwise to increase flow index or clockwise to reduce flow index to match the desired setting. (NOTE: After a long pause, the green status light will blink long-blinks for the tens count of the flow rate index, which is then immediately followed by fast blinks which indicate the second digit. For example, a flow index of 23 would be two long blinks, followed by 3 fast blinks of the green status light.)
3. On the exhaust motor control board (LH side of control panel), observing the green status light, turn the manual adjust potentiometer counterclockwise to increase flow index or clockwise to reduce flow index to match the desired setting. (See NOTE in Step 2.)

Figure 1: ERV Control Access

This figure illustrates the access points for the ERV components. The main unit has front swinging doors that can be opened by releasing latches. Removing five (5) screws from the ERV door provides access to the ERV components. The ERV control panel is located within the unit. The ERV intake blower is visible. The ERV exhaust blower is located behind the intake blower. The ERV cassette assemblies are also shown.

Figure 2: Control Board Configuration/Setting

This figure shows the ECM Motor Control Cable connections and the control board layout. Key connections include:

• To Automation Controller: Control Signal, Signal Common, RPM Out.
• 0-2,000 RPM = 0-10Vdc
• Aux Power: Common, 24Vac/dc, 24Vac/dc.
• Signal Common, Aux Common & Neutral/Common: Internally connected.
• Class II Power Source: Earth neutral/Common at transformer for electrical safety.
• Neutral/Common

The control board features:

• Board mode pins: Factory shipped on "M" pin for On/Off control scheme using "A" signal on low voltage control board.
• Red status light: Indicates when the unit has power.
• Green signal light: Continuously indicates the flow index the blower is producing. After a pause, it flashes long digits for the tens count, followed by short flashes for the units count (1-99). For example, a flow index of 23 yields two long flashes and three short flashes.
• Manual adjust screw: Used in manual mode ("M" jumper installed) with the green signal light to adjust to the required CFM. Clockwise rotation reduces the flow index; counterclockwise rotation increases the flow index.

Energy Recovery Ventilator Maintenance

General Information

Maintaining clean exposed surfaces within air moving systems is crucial for system performance and air quality. Cleaning needs depend on operating schedule, climate, and indoor/outdoor air contaminants. All components exposed to the airstream, including energy recovery wheels, may require cleaning.

Rotary counterflow heat exchangers (heat wheels) with laminar airflow are generally "self-cleaning" for dry particles. However, films of oil-based aerosols can condense on surfaces, reducing airflow and, importantly, closing off desiccant pores on enthalpy wheels, diminishing moisture absorption/desorption efficiency.

Frequency

In clean environments (schools, offices, homes), airflow or sensible effectiveness reductions may not occur for 10+ years. Measurable changes in latent energy (moisture) transfer can occur sooner in commercial/residential settings with moderate smoking or cooking. Applications with high occupant smoking (lounges, nightclubs, bars, restaurants) or industrial settings with smoke/oil aerosols (welding, machining) may require washing energy transfer surfaces as frequently as every 6 months to maintain latent transfer efficiency. Latent efficiency losses of up to 40% or more can develop in 1-3 years in these demanding applications.

Cleanability and Performance

Energy transfer surfaces must be accessible for washing to remove oils, grease, tars, and dirt that impede performance or cause odors. Washing desiccant surfaces removes contaminant buildup that reduces water molecule adsorption. The continued ability of an enthalpy wheel to transfer latent energy depends on the permanence of the desiccant bond to the heat exchange surfaces.

Bard wheels feature silica gel desiccant permanently bonded to the heat exchange surface without adhesives, ensuring the desiccant is not lost during washing. Proper cleaning restores latent effectiveness to near original performance.

Maintenance Procedures

NOTE: Local conditions vary, affecting maintenance schedules. The following timetables are recommended and can be altered based on local experience.

Quarterly Maintenance

1. Inspect the mist eliminator/prefilter (located in the fresh air intake hood on the front of the unit) and clean if necessary. This aluminum mesh filter can be cleaned with water and a mild detergent.
2. Inspect the wall-mount unit filter and clean or replace as necessary. This filter may be in the unit itself (accessed by removing the lower service door) or in a return air filter grille assembly (accessed by hinging the grille open).
3. Inspect the energy recovery ventilator for proper wheel rotation and dirt buildup. This can be done in conjunction with filter inspection. Energize the ventilator after inspection to observe rotation and buildup.
4. Recommended energy recovery wheel cleaning procedures follow Steps 5 through 8.
5. Disconnect all power to the unit. Remove the lower service door of the wall-mount unit to access the energy recovery ventilator.
6. Remove the front access panel on the ventilator. Unplug amp connectors to cassette motors. Slide the energy recovery cassette out of the ventilator.
7. Use a shop vacuum with a brush attachment to clean both sides of the energy recovery wheels.
8. Reverse the shop vacuum to use it as a blower and blow out any residual dry debris from the wheel.

   NOTE: Discoloration and staining of the wheel does not affect its performance. Only excessive buildup of foreign material needs to be removed.

9. If any belt chirping or squealing noise is present, apply a small amount of LPS-1 or equivalent dry film lubricant to the belt.

Annual Maintenance

1. Inspect and conduct the same procedures as outlined under Quarterly Maintenance.
2. To maintain peak latent (moisture) removal capacity, it is recommended that the energy recovery wheels be sprayed with a diluted non-acid based evaporator coil cleaner or alkaline detergent solution such as 409.

   NOTE: Do not use acid-based cleaners, aromatic solvents, temperatures in excess of 170°F, or steam, as damage to the wheel may result.

   Do not disassemble and immerse the entire heat wheel in a soaking solution, as bearing and other damage may result.

3. Rinse the wheel thoroughly after application of the cleaning solution, and allow it to drain before re-installing.
4. No re-lubrication is required for the heat wheel bearings of the drive motor, or for the intake and exhaust blower motors.
5. If any belt chirping or squealing noise is present, apply a small amount of LPS-1 or equivalent dry film lubricant to the belt.

Figure 3: Hub Assembly with Ball Bearings

This figure illustrates the components of the hub assembly with ball bearings for the energy recovery wheel. The assembly includes:

• HUB ASSEMBLY WITH BALL BEARINGS
• SCREW #6 x 32 x 3/4
• DUST COVER
• SCREW #10 x 32
• WASHER
• NUT #10 x 24
• SPACERS
• HUB PLATE
• BEARING
• HEAT EXCHANGER WHEEL
• HUB PLATE WITH BOLTS
• SHAFT (OIL WITH 20 WT. NON-DETERGENT OIL)
• LOCK WASHER
• NUT 1/4 x 20

Figure 4: Ventilation Airflow Diagram

This diagram illustrates the airflow paths within the I-TEC ERV system. The main air streams are:

• Indoor Air / Return Air: Drawn into the unit, passes through the ERV cassette assemblies, and is then exhausted.
• Outdoor Air: Drawn into the unit, passes through the ERV cassette assemblies, and is then supplied as conditioned fresh air.
• Supply Air: The conditioned outdoor air is delivered to the space.

Key components shown in the airflow path include:

• VENT INTAKE BLOWER: Pulls indoor air and pushes outdoor air through the heat exchanger.
• VENT EXHAUST BLOWER: Expels stale indoor air.
• SUPPLY BLOWER: Delivers conditioned outdoor air.
• ERV CASSETTE ASSEMBLIES: Where heat and moisture transfer occurs between the exhaust and intake air streams.

Performance and Application Data

Summer Cooling Performance (Indoor Design Conditions 75°DB/62°WB)

Winter Heating Performance (Indoor Design Conditions 70°F DB)

LEGEND:

• VLT = Ventilation Load – Total
• VLS = Ventilation Load – Sensible
• VLL = Ventilation Load – Latent
• HRT = Heat Recovery – Total
• HRS = Heat Recovery – Sensible
• HRL = Heat Recovery – Latent
• WVL = Winter Ventilation Load
• WHR = Winter Heat Recovery

NOTE: All performance data is based on operating intake and exhaust blower on the same speed.