open_erv2

Well this was fun and thanks for the discussion, everyone. People are surprisingly nice and sensible and positive here! I used to have another account but lost the password. Perhaps I'll be a reader here in the future.

Anyway, I've tried to turn the very temporary influx of interest into something positive and lasting by searching for 2 people who can install and document the install of a pair of TW4 energy recovery ventilators, so anyone who wishes to buy thereafter can know what they are in for on that count. There is another guy Alex who will test flow and efficiency, I've already sent him the stuff.

So we get things tested and verified, and I will continue getting a jump on producing units by running the printers and assembling in between when I am doing the more respectably paid work in my life. The kits are on the back burner because even I am still stabilizing the assembly methodology. I even added a new component just recently, a flow straightener that boosts flow by about 10% while allowing noise to be reduced even further.

So stabilize, verify, produce, and then after that, within a couple months, I sell in a more or less ordinary way to anyone who wants them. I'm sorry it's not in time for the cold weather, but we have to remember ERV is about the big picture and long term. Like the rest of a building, it's an investment, and the machines are made for (very) good return and long lifespan.

I will prepare some WM12 units for those who have asked for them. To be clear I only got 12 emails expressing interest, not an absolute flood, but it's encouraging to know some people "get it" at least. I knew there would only ever be a small trickle of relatively wise people from around the world that appreciate good performance and return on investment. I only need to sell a few pairs per month to make it worthwhile, at the eventual $1300 CAD price tag.

I am open to scaling up production with more efficient production methodologies, but I am actually fairly well acquainted with injection molding, machining and other conventional approaches, and they aren't magic. They would help for sure but they wouldn't radically change the price, or the rate of return on investment, and they also take a lot of investment not just for tooling but also re-testing and re-design. I've also changed the design so, so many times after I thought it was done I am highly wary of being locked in.

Yeah that would probably work, it's just a matter of cost. A lot of people balk at $700 CAD, the eventual price is supposed to be $1300 for a pair, you do that and you are looking at a lot of $ for the flow and energy recovered.

The numbers are the number of versions before it stabilized, so 12 tries for the window mount, 4 for the through wall. It took a while.

I have a spreadsheet where I track all inputs, and unfortunately it's just the cost of everything. The filament really doesn't help, but it also takes a lot of labor, and paying off the dev cost is also an important factor. Most of all, it's made in Canada where rent is expensive and I have pay that so I have to get paid a living Canadian wage.

thanks will do

I have traced the air with a smoke generator, there is a youtube video of me doing this on my youtube channel. There is not significant re-inhalation (short circuiting) of the air. The reason for the window mount is that a lot of people rent or otherwise cannot punch holes in their walls. However the reason the window mount is nearly the same as the TW4 (through wall) type, is that I cannot invest the time and money to re-design a whole new machine for a window. The primary value is in the TW4, but a lot of people wanted window mount ones so I helped some people out by deving a quick window adapter and then they helped me out by testing some of the components/the fundamentals of the system in the real world. Unfortunately the window mount units nobody is willing to really pay the cost of manufacture for, so they have to use grade B parts etc. and they have to serve the purpose of testing the TW4 or they aren't worth making.

That is half correct. The TW4 units operate in synchronized pairs. When one is exhausting (egressing), the other is ingressing (bringing air in). This always happens. They even have quite nice pressure sensors that precisely regulate the pressure the fans exert, controlling flow precisely and preventing the house from becoming pressurized at any time, which as you say would imply heat loss.

You have to look closely at the actual test protocol, which they rarely share. And in reality noise is hard to measure and hard to understand. There is also SPL and SWL, which are not the same. The marketing department has no clue and convert back and forth with approximations, adding or losing decibels, and nobody ever checks or really knows or, usually, cares. We need third party reviewers with actual sound meters or the numbers mfrs give us are practically useless. This is why I am prioritizing selling beta units to people who can actually test the units.

There is some stuff in the other projects page on the website, that project went really well too, I spend most of my time on that these days, the ERV is a longer term thing, the fan has a finish line but in a way is more epic/important because it's about halting airborne disease transmission. It works extremely well, about 1900 CFM through merv 13 filters (10x 20 by 25 filtrete) at less than 41 dBa.

I invented a process using some environmentally friendly solvents, grinding the sorbent and so on. It is not diy friendly unfortunately so there is little point in sharing the recipe.

My price is for a pair, remember, not one. And those pioneer things don't work very well, poor flow and efficiency unfortunately. They claim high efficiency but it's only at the lowest flow rates and not the average for the cycle, only at the beginning of the cycle. There is one company that keeps emailing me trying to sell me units wholesale, I keep telling them to send me actual test data and then I might buy some (for testing), and they never do.

The MPLA (not pla) does not absorb the water vapor, but it condenses on the plastic and then evaporates. There is also the option of sorbent, which grabs the water vapor and then releases it with each cycle, before condensation occurs, getting higher efficiency.

The material in the whispercomfort is IIRC a fiberglass paper. It can only transfer liquid water, not solid water, and not vapor, effectively. The water condenses, whets the paper, then evaporates out the other side. It's a reasonable approach but does not work well in very low temperatures, and also the condensation process implies certain limits to efficiency, same as a non sorbent coated regenerative heat exchanger. The water doesn't start to condense until 100% RH, so it is 100% when it leaves the exchanger, while the air coming in is lower than that, usually. Thus water is lost.

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.

There is the tw4, which is made to be put in a wall, and there is the WM12, which goes in the window. The main focus is the TW4. There are instructions in the manual for making an ERV core. It is not trivial.

I'm planning to just putter along selling units, making about 50% of my living like that, and if a company comes along and wants to buy the design/company that's good. If not, I get some stuff done, earn a living. This isn't a get rich quick scheme, it's an honest living type stuff.

That's an amazing project! I'm blessed to be in such company. Seriously, I use open source stuff and I prefer to do business with such relatively wise people. If you want a beta unit, email me and I'll put you at the top of the list!