Balancing ERV/HRV, Magnehelic gauge placement

BALANCING ERV/HRV

Balancing intake and exhaust airflow is very important for proper system operation and optimum performance when applying an ERV/HRV. Unit balancing prevents a positive and/or negative pressure within the home. Balancing the ERV/HRV is done by applying magnehelic gauge and using the balancing dampers at the fresh air intake and stale air exhaust ducts. (See Fig. 13.)

Balancing

Chart

Fresh air flow

1	12	12	11
1	12	12	11
3 13 33 23				Exhaust air flow
1	12	12	11
1	12	12	11
3 13 33 23

See Detail A

DETAIL A

Port with integrated balancing damper Top View

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Fig. 13 - Balancing ERV/HRV

Airflow is determined by temporarily connecting a magnehelic gauge to the pressure taps on ERV/HRV. (See Fig. 14.) Balancing chart is located on unit door.

A98400

Fig. 14 - Magnehelic Gauge

If supply-air from outside is greater than exhaust-air from the house, an imbalance can result over pressurizing the home. If exhaust-air is greater than supply-air, combustion appliances may backdraft, bringing exhaust fumes into the house. A balanced condition will ensure optimum performance, provide satisfied customers, and avoid expensive callbacks.

Before proceeding with balancing, all windows, doors, and fireplace flues should be tightly closed. No exhaust systems such as range top exhausts, dryer exhaust, fume hoods, bath or roof fans should be in operation. The forced-air furnace (if used for circulation) should be operating in continuous fan mode for normal operating speed.

Balancing Procedure

Step 1 — Set the unit to high speed.

Make sure that the furnace/air handler blower is ON if the installation is in any way connected to the ductwork of the cold air return. If not, leave furnace/air handler blower OFF. If the outside temperature is below 32_F (0_C), make sure the unit is not running in defrost while balancing. (By waiting 10 minutes after plugging the unit in, you are assured that the unit is not in a defrost cycle.)

Step 2 — Magnehelic gauge placement.

Place the magnehelic gauge on a level surface and adjust it to zero.

Step 3 — Connect tubing from gauge to EX- HAUST air flow pressure taps.

Be sure to connect the tubes to their appropriate high/low fittings. (See Fig. 13.) If the gauge drops below zero, reverse the tubing connections.

NOTE: It is suggested to start with the exhaust air flow reading because the exhaust has typically more restriction than the fresh air, especially in cases of fully ducted installations or source point ventilation. Place the magnehelic gauge upright and level. Record equivalent AIR FLOW of the reading according to the balancing chart.

Step 4 — Move tubing to FRESH air flow pressure taps.

Adjust the fresh air balancing damper until the fresh air flow is approximately the same as the EXHAUST air flow. If fresh air flow is less than exhaust air flow, then go back and adjust the exhaust balancing damper to equal the fresh air flow. (See Fig. 13.)

Step 5 — Secure both dampers thumb screw in place with tape.

Step 6 — Record air flow information.

Write the required air flow information on a label and stick it near the unit for future reference (date, maximum speed air flows, your name, phone number and business address).

NOTE: The unit is considered balanced even if there is a difference of ±10 CFM (or ±5 l/s or 17 m3/h) between the two air flows.

Balancing Dampers

Balancing dampers (sometimes called butterfly dampers) are located in fresh-air intake and stale-air exhaust of the ERV/HRV. (See Fig. 13.) Insulating over these dampers is strongly recommended after balancing is complete to prevent condensation problems.

Bryant ERVBBSVA1100 Balancing ERV/HRV, Balancing Procedure Set the unit to high speed