Bugs going in the ERV, how to avoid?
![](https://secure.gravatar.com/avatar/b38e187ff129f56a9091e6b13a28589b?s=52&d=https%3A%2F%2Fimages.greenbuildingadvisor.com%2Fapp%2Favatars%2F200x200%2Fs.png&r=g)
I have a panasonic IB200 with hepa filter inside it and noticed wayyyyy too many bugs inside the erv, the holes on the grill on the outside intake air is too big, anything I can do?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
![](https://www.greenbuildingadvisor.com/app/themes/greenbuildingadvisor/dist/img/modules/detail-library/thumb1.png)
![](https://www.greenbuildingadvisor.com/app/themes/greenbuildingadvisor/dist/img/modules/detail-library/thumb2.png)
Replies
If you search, you will see a previous question about adding an inline filter prior to the ERV, using a Fantech in line filter. They are 80-90% efficient, so some impact will occur and anyway, you are just changing the location of where the bugs get stopped. In another post, it is explained that you can't make the outside filter grill any finer because it has to meet code "If a protective mesh is used, the mesh must be no smaller than 0.25 inch to minimize dirt build-up or obstruction"
So, the best I could come up with was to buy a mini shop vac and leave it sitting next to the ERV and pull out the filter once in a while and vacuum it off between replacement cycles.
Ok I can put a screen that has 0.25” holes? Mine right now is like 0.5”-0.75
Probably a question for a local code expert. My understanding is that the .25 is measured diagonally. so not sure exactly what size screen will work for you.
btw, the Zehnder outside grill that we use is described as a 'vermin grill' not an insect grill. I don't like messing with any of the Zehnder stuff to avoid warranty issues, so I have not considered changing to a finer screen. https://zehnderamerica.com/wp-content/uploads/2019/09/Zehnder-External-Grille-specification-2019.09.16.pdf
I know you say code but there is no code for my building, my house didnt even have an air exchanger
Glad you posted this. I have a similar problem with a Panasonic FV-04VE1, a standalone unit.
If I just let the exterior "vermin control" grill be, small bugs get into the duct, somehow get through the intake filter, get into the exchange core, and even come out the fresh air supply and end up dead on the floor at the unit.
If I install a piece of standard fiberglass screen directly behind the vermin control grill, far fewer bugs get in the system and on the floor, but the fiberglass also very quickly mats up with dead bugs and pollen.
I've considered installing a filter grill with a boot transition to the 4" duct, and using either cheap fiberglass media or a low MERV 8 filter in the filter grill...but very open to suggestions.
The main lesson here is for those whose installations are not yet complete - FIGURE OUT A WAY to install a larger than needed filter that is easily accessible.
"FIGURE OUT A WAY to install a larger than needed filter that is easily accessible"
+1 Don't underestimate access, hard to replace quickly becomes never replace.
As for bugs, I live with it. When I clean my intake filter there is always bugs in there but they are mostly dead so they get vacuumed out. Keeping the intake far away from any outdoor lights helps a bit.
All good I put a 0.25” screen and prior to this it was a 1” holes screen. I will just vacuum the intake grill once a month to make sure its not clogged
One solution you can consider is adding a finer mesh or screen over the intake grill. This can help filter out smaller insects and prevent them from entering the system. It's a relatively simple and cost-effective fix that can make a significant difference.
Additionally, you might want to ensure that your existing filters, like the HEPA filter you mentioned, are in good condition and regularly maintained. Clean filters can also help trap bugs and prevent them from spreading further into your system.
If you're looking for more comprehensive solutions, you can check out https://www.damagecontrol-911.com/killing-bugs-and-mold-with-ozone-generators/. It provides insights into dealing with bugs and mold in ventilation systems, which might offer additional tips and strategies to keep your ERV bug-free.