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I'd love to build this. I have access to a 3d printer, use Python, and have some electronics experience. I live in a northern climate and have been eyeing ERV s

I'd love to build this. I have access to a 3d printer, use Python, and have some electronics experience. I live in a northern climate and have been eyeing ERV systems for a while. Basically, I'm the perfect target for this. However, reading the docs, they seem written more to discourage any kind of DIY attempt by saying things A, B or C are difficult, than actually explaining how to do them correctly. I'd love to contribute to the project, but it feels like it's not set-up to foster community contribution. If I'm mistaken, I'd love to donate some of my time on this!

Aurornis 2y ago
I expected a community open source project from the title, but reading the docs led me to the same conclusion: The website is about convincing you to buy one while discouraging you from attempting to build one. It looks like a fun project. I don’t want to discount what has been designed and built. It is confusing to start reading about the project and discover that it’s more of a business than a community project while simultaneously being unavailable for purchase. The person who built it commented on HN that they’re focused on a 3rd different fan project right now, which brings the future of this project into question. It would be great if a community effort could fork this project and work on making it easier to DIY so the community could push it forward. EDIT: After exploring the files I’m not sure I’d even call this open source. I either can’t find some key files or they’re deliberately excluded. True open source projects would also include the CAD source, not only .STLs so others could adapt and modify the source. I think the open angle on this project is more marketing than substance.
- open_erv2 2y ago
  The step files are also there, which is the best common denominator for CAD files. Again, it's open source for the purpose of maintenance and repair, not cloning, and frankly earlier on I did make it more community oriented and nobody ever contributed even a little bit, so I just gave up on that idea. The most likely scenario for longer term is that people may submit minor patches or suggestions, which I roll into the hardware or firmware. In reality, hardware is not like software. You can't make changes easily. Some wizards may take it upon themselves to spruce up the firmware with fancy features and release something, which anyone is free to do. There would then be multiple compatible versions of the firmware, one which I curate for reliability with minimal features, and others which others can provide. Same as for 3d printer firmware. The firmware is Micropython, which is extremely easy to understand and modify.
- zajio1am 2y ago
  It is not open source (per OSI definition), as it is under CC BY-NC-SA.
turtlebits 2y ago
Unfortunately the recovery core, which is the interesting part of an ERV, is not included in the 3d stl's. IMO, this feels like a more marketing project than anything open. ERVs are already very simple (a recovery core + blowers/fans). Commercial units last an extremely long time (some with 10 year warranties) and have comprehensive parts availability. Also a long term window install is a bit janky and is likely to lose out on efficiency due to glass being a poor insulator.
- NavinF 2y ago
  I'm pretty sure stls/regen.stl is the recovery core you're taking about tho I can't open it in a online stl viewer: https://drive.google.com/drive/folders/1py2YwmwBEcvmdw18SKwxB1GOhuY4MVy- https://drive.google.com/drive/folders/1py2YwmwBEcvmdw18SKwx... In the photos it seems to be a bunch of nested single-perimeter cylinders that are joined at a few points to maintain spacing. Easy enough to model, but I agree the documentation is horrible and there's no way to contribute. Commercial units are not comparable because they're way more expensive despite being so simple
  - bittercynic 2y ago
    Prusaslicer opens it, and it is the right size and shape to be the core, but there's no internal geometry in that STL, at least not how Prusaslicer renders it. I'd be interested in seeing a diagram of how the air flows through it, if such a thing is available. Edited to add: There are instructions in the WM12 manual to use your infill settings to make the old version of the core. Page 15 of the manual states there is a python script in the source files to generate the new core, but it only works for their particular printer. I wasn't able to find the script.
    - schneems 2y ago
      Thanks for mentioning that. It seems the PDF and the google docs "manual" have diverged a bit. (at least in page numbers). I was curious about materials for the core. I know that they're supposed to exchange humidity as well as heat. I know PLA will absorb and release water but I would guess it wouldn't transfer enough to be very efficient. Though I would be happy to be wrong. I assume the Core in my Panasonic whisper comfort was made out of something more permeable than "simply" extruded plastic. (would love to know more if someone has details).
outlog 2y ago
just saw this video https://www.youtube.com/watch?v=U-hVUczzlL4 https://www.youtube.com/watch?v=U-hVUczzlL4 and you get a very smart solution for a fair price, that does coordination etc.. and it's even esp32 based should the need arise. see https://www.bpcventilation.com/bsk-zephyr-single-room-heat-recovery-unit https://www.bpcventilation.com/bsk-zephyr-single-room-heat-r... I also have this DIY bookmarked: https://www.youtube.com/watch?v=wJB3dyHDa-8 https://www.youtube.com/watch?v=wJB3dyHDa-8

Aurornis 2y ago

I expected a community open source project from the title, but reading the docs led me to the same conclusion: The website is about convincing you to buy one while discouraging you from attempting to build one. It looks like a fun project. I don’t want to discount what has been designed and built. It is confusing to start reading about the project and discover that it’s more of a business than a community project while simultaneously being unavailable for purchase. The person who built it commented on HN that they’re focused on a 3rd different fan project right now, which brings the future of this project into question. It would be great if a community effort could fork this project and work on making it easier to DIY so the community could push it forward. EDIT: After exploring the files I’m not sure I’d even call this open source. I either can’t find some key files or they’re deliberately excluded. True open source projects would also include the CAD source, not only .STLs so others could adapt and modify the source. I think the open angle on this project is more marketing than substance.

open_erv2 2y ago
The step files are also there, which is the best common denominator for CAD files. Again, it's open source for the purpose of maintenance and repair, not cloning, and frankly earlier on I did make it more community oriented and nobody ever contributed even a little bit, so I just gave up on that idea. The most likely scenario for longer term is that people may submit minor patches or suggestions, which I roll into the hardware or firmware. In reality, hardware is not like software. You can't make changes easily. Some wizards may take it upon themselves to spruce up the firmware with fancy features and release something, which anyone is free to do. There would then be multiple compatible versions of the firmware, one which I curate for reliability with minimal features, and others which others can provide. Same as for 3d printer firmware. The firmware is Micropython, which is extremely easy to understand and modify.
zajio1am 2y ago
It is not open source (per OSI definition), as it is under CC BY-NC-SA.

turtlebits 2y ago

Unfortunately the recovery core, which is the interesting part of an ERV, is not included in the 3d stl's. IMO, this feels like a more marketing project than anything open. ERVs are already very simple (a recovery core + blowers/fans). Commercial units last an extremely long time (some with 10 year warranties) and have comprehensive parts availability. Also a long term window install is a bit janky and is likely to lose out on efficiency due to glass being a poor insulator.

NavinF 2y ago
I'm pretty sure stls/regen.stl is the recovery core you're taking about tho I can't open it in a online stl viewer: https://drive.google.com/drive/folders/1py2YwmwBEcvmdw18SKwxB1GOhuY4MVy- https://drive.google.com/drive/folders/1py2YwmwBEcvmdw18SKwx... In the photos it seems to be a bunch of nested single-perimeter cylinders that are joined at a few points to maintain spacing. Easy enough to model, but I agree the documentation is horrible and there's no way to contribute. Commercial units are not comparable because they're way more expensive despite being so simple
- bittercynic 2y ago
  Prusaslicer opens it, and it is the right size and shape to be the core, but there's no internal geometry in that STL, at least not how Prusaslicer renders it. I'd be interested in seeing a diagram of how the air flows through it, if such a thing is available. Edited to add: There are instructions in the WM12 manual to use your infill settings to make the old version of the core. Page 15 of the manual states there is a python script in the source files to generate the new core, but it only works for their particular printer. I wasn't able to find the script.
  - schneems 2y ago
    Thanks for mentioning that. It seems the PDF and the google docs "manual" have diverged a bit. (at least in page numbers). I was curious about materials for the core. I know that they're supposed to exchange humidity as well as heat. I know PLA will absorb and release water but I would guess it wouldn't transfer enough to be very efficient. Though I would be happy to be wrong. I assume the Core in my Panasonic whisper comfort was made out of something more permeable than "simply" extruded plastic. (would love to know more if someone has details).

outlog 2y ago

just saw this video https://www.youtube.com/watch?v=U-hVUczzlL4 https://www.youtube.com/watch?v=U-hVUczzlL4 and you get a very smart solution for a fair price, that does coordination etc.. and it's even esp32 based should the need arise. see https://www.bpcventilation.com/bsk-zephyr-single-room-heat-recovery-unit https://www.bpcventilation.com/bsk-zephyr-single-room-heat-r... I also have this DIY bookmarked: https://www.youtube.com/watch?v=wJB3dyHDa-8 https://www.youtube.com/watch?v=wJB3dyHDa-8