Replies

1. 
   DennisWood | Dec 05, 2022 10:01am | #1

   The unit was designed to flow it's rated CFM, with the filters in place.

   That said, you can increase air flow by using MERV 8s internally (to keep dust out of the core) and use an external inline filter box like these. The 6" or 8" version will work fine in your application and have much lower resistance than the smaller filters in your ERV.

   https://www.hvacquick.com/products/residential/Air-Filters/Inline-Filter-Boxes/HVACQuick-CFB-Series-MERV-13-Inline-Filter-Boxes

   I'm using the 6" version and have measured pressure drop at around 10 pascals across the filter at 100 CFM...very low. I have this on the warm side (supply) so I did not have to insulate the box.

1. 
   Shawnnixon1 | Dec 05, 2022 11:48am | #2

   Thank you Dennis how much more flow will i be getting by putting a merv 8 from 13

2. 
   DennisWood | Dec 05, 2022 12:12pm | #3

   This will vary widely between filters so there is no easy way to answer that other than testing on the unit itself. Set the unit to the max, 200 CFM. Check pressure across the core (balancing ports) using a differential magnehelic gauge with the different filters installed. You'll have your answer. If you are still concerned with volume, install MERV 8 filters inside the ERV and use the MERV13 inline filter box I linked t0. I could only guess at a 10-20 CFM increase over what you're seeing now.

   The foam/screen filters in my "test" Venmar HRV unit definitely reduce flow when in place by 6-8%...and they are MERV4-6, at best.

   The external inline air filter with a 14x14x4" MERV13 has less resistance than the OEM filters (around 15"x7") on my test unit.

1. 
   Deleted | Dec 05, 2022 12:14pm | #4

   Deleted

3. 
   DennisWood | Dec 05, 2022 12:28pm | #5

   Balancing dampers can go on the warm side of the ERV, supply and return. Your ERV balancing chart shows that supply and return pressures are pretty close. In your case you'd want a damper on both supply and return.