Hello,
DHT22 are more accurate than DHT11 and a lot cheaper than Sensirion SHT. As I read they are stable, so some offset error is easily corrected by software.
Thanks for info about T6004, I will include power control so in case of erratic reading I can reset it. I also saw some cheat CO2 sensor, but I can't remember where.
As of dP sensor I plan to use I2C sensor from HYB. My wife sells them so I guess it shouldn't be a problem to get one free sample
. I use hydronic floor heating, but also have a fireplace installed in the living room. I use it from time to time to get that good warm feeling in the winter. To prevent smoking the house and possible CO build up, I need a small positive pressure in the house. I plan to control suction fan speed and inake fan will follow by just balancing the pressure differential. At least that is in theory.
I haven't try flow sensor yet. I want to measure flow 0-100%, not in real values. Maybe these sensor will have no use, but I will plan them in the mainboard anyway.
Ventilation will be based on timer and house air humidiy. Since in the house live only 4 people, humidity build up is more problem than CO2. So CO2 meter will be there just for show-off
Ethernet will be used for reporting data to COSM (now Xively). Also future plan is to build a graphical web page with all current data/settings.
RS485 is for remote wired LCD and keypad.
For now I am still in selecting hardware components.
best regards, Damo