Open_erv

5 ms·

1.
by Open_erv 3y ago
BTW that regenerator did the 45 cfm at 3.25 mm H2O of air pressure.
2.
by Open_erv 3y ago
I can actually get small thermistor based hot wire anemometers for about a dollar, so I can just use those with a PID control loop to control fan speed. Then the flow is quite well regulated. However high winds will overwhelm the fan, a pr
3.
by Open_erv 3y ago
Yes, that's correct.
4.
by Open_erv 3y ago
You can 3d print one actually, it works pretty well. The only problem is the alumina has a higher volumetric heat capacity, of about 3.5, whereas PLA has 2.25. Which is pretty high. The thermal conductivity isn't a big deal, the mai
5.
by Open_erv 3y ago
They vary considerably, the aliexpress ones are about as good, but none of them are very good, they give more like 70% efficiency at the medium flow rate, overall. Not what they claim. They do work though.
6.
by Open_erv 3y ago
BTW don't know if I said this, but there are some reversible fans on digikey that should work. I was going to open them up and paint them with dielectric grease for water resistance. I ordered the 136 mm diameter one, they are pretty
7.
by Open_erv 3y ago
Yes, I agree :). I don't know if you saw my proposal to Kanro, an anti-pandemic charity, to develop a fan for a superior CR box. I think it will be really good if they chose to fund it, it bothers me that they take several months to
8.
by Open_erv 3y ago
I don't like the telescopic ducts because they can leak into the wall cavity. There is nearly no point in adding more mass. It does increase efficiency but the typical regenerators are alumina which already have a lot of thermal mass
9.
by Open_erv 3y ago
They all are capable of doing so under some circumstances with limited efficiency, because as the air exits the house and cools down at some point water condenses out of the air onto the regenerator media. Then it evaps again when flow rev
10.
by Open_erv 3y ago
You can understand quantitatively how this goes for different areas using Heating degree days and Cooling degree days, factoring in latent heat in both cases, ideally. There are calculators for this. I made a spreadsheet on my website www
11.
by Open_erv 3y ago
This is approximately correct, except for one big problem with counterflow exchangers, which is frost. Even the membrane types still frost up. What you really want is a regenerator, either a thermal wheel or a fixed matrix regenerator, if
12.
by Open_erv 3y ago
There was a period where I considered DIY for such machines impractical. I now think that to diy all the way through is impractical, the design process is too laborious even for those suitably skilled. However once the design is worked ou
13.
by Open_erv 3y ago
I'm the OpenERV guy. It's been a long road and it's not very open source any more I'll admit, however I did publish a bit Wikifactory article with all the cad etc. for a quite efficient window mount unit. I now have th