ERV comparison – unit balancing

We were owners of several UltimateAir RecoupAerator 200DX energy recovery ventilators (ERVs), until they broke down. And like so many other former 200DX owners, we found ourselves hunting for some suitable replacements. We settled on the Broan ERV200TE and Panasonic FV-20VEC1 (Intelli-Balance 200).

In this post I am comparing the balancing protocol of these two units. I hope you will find the information useful if you are in a similar situation.

All ERVs in our building have their own dedicated duct work, rather than being connected to an air furnace duct as we don’t have forced air heating.

Why balancing?

When using mechanical ventilation, it is a good idea to avoid negative pressure (exhausting more air than comes in) and positive pressure (forcing more air into the building than can leak out). Depending on the weather conditions, negative or positive pressure has the potential to cause condensation where air leaks into or out of the building, which in turn could lead to mold formation.

A balanced mechanical ventilation system, such as many ERVs, avoids this risk by balancing the supply air with the exhaust air. However, because the supply and exhaust duct systems may have different lengths and a different number of fittings, such as elbows, it may create different static pressures. Balancing the ERV should compensate for the difference in static pressures.

To proceed with the balancing process, I had to purchase a magnehelic gauge, which allows me to measure the pressure on the supply and exhaust sides of the ERV. The pressure gets converted to cubic feet per minute (cfm), which is the metric used to adjust the airflow until the unit is balanced.

Broan Balancing

To balance the Broan, the user has to access the programming mode through the VT9W wall control. This wasn’t much of an obstacle, as I needed the wall control anyway in order to run the ERV.

The Broan has four small ports, two on the supply side and two on the exhaust side. The magnehelic gauge tubing gets connected to the ports to take pressure readings and determine the air flow rate for the various settings (turbo speed, continuous speed, timer speed, and recirculation speed). Through the wall control, I could enter the program mode and then adjust the airflow, or motor speed, for the various settings in 1% increments until the unit was balanced.

I found the instructions in the installation guide intuitive and easy to follow, and recorded each setting for future reference.

Panasonic balancing

The Panasonic is balanced with the controls that are on the unit. Like the Broan, it has four small ports for the Magnehelic Gauge tubing to take pressure readings and determine the air flow rate.

The balancing instructions (or start-up procedure instructions), are incomplete and confusing – so much so that I ended up calling tech support. Tech support tried their best to help me with my questions but didn’t have the answers on some of the technical details. I was referred to the Panasonic engineers, but never heard back from them, despite repeatedly contacting them for a month. In short, it took a lot of research to partially wrap my head around the balancing procedure for the Panasonic.

To balance the Panasonic I measured the airflow on the supply and exhaust side for all eight ventilation stages.

CFMSupply pressure (PA)Exhaust pressure (PA)
6019.627.5
8024.538.2
10034.348.1
12041.258.8
14048.173.5
16062.873.5
18075.574.5
20079.474.5

I then had to pair the supply and exhaust air volume based on the closest matching airflow readings.

SupplyExhaust
80 cfm (24.5 Pa)60 cfm (27.5 Pa)
100 cfm (34.3 Pa)80 cfm (38.2 Pa)
120 cfm (41.2 Pa)80 cfm (38.2 Pa)
140 cfm (48.1 Pa)100 cfm (48.1)
160 cfm (62.8 Pa)120 cfm (58.8 Pa)
180 cfm (75.5 Pa)180 cfm (74.5 Pa)
200 cfm (79.4 Pa)200 cfm (74.5 Pa)

If I want to run the ERV at 60 cfm, I need to set the supply side to 80 cfm and the exhaust side to 60 cfm. If I want to run the ERV at 80 cfm, I need to set the supply side to 100 cfm and the exhaust side to 80 cfm. And so on…

This process seemed rather crude compared to the Broan where I could adjust the airflow in 1% increments. That said, Panasonic advertises in their product literature something called  SmartFlow™ technology:

Intelli-Balance®200 uses two (2) ECM brushless motors with built-in SmartFlow™ technology for precision ventilation. When the ERV senses static pressure, its speed is automatically increased to ensure desired output; regardless of a complicated duct run.

I was unable to find more technical information that would shed light on how the SmartFlow™ technology exactly works. Some suggested in discussion forums that the SmartFlow™ technology auto balances the Panasonic as long as the pressure differential does not exceed 0.4” WG (99.5 Pa).

Bottom line, after I paired the correct airflow settings as per the table above and tested the Panasocnic again, I got the same pressure readings on the supply and exhaust side, which indicates that the SmartFlow™ technology seems to do its job.

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About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

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