EcoRenovator - View Single Post - Arduino CO2 Sensor Controls PCM Fans in HRV

AC_Hacker · 03-23-13, 03:16 PM

It is interesting how instrumentation can give us an awareness of previously unseen things.

My desk is set at a wall, facing out through a window. I generally do my Internet work there as well as small electronic projects, such as my CO2 sensor.

Having a CO2 monitor on my desk now for several weeks has been a real awakening to the CO2 bubbles we create around ourselves if we are in still air. I know this because I have another CO2 monitor hanging on the wall about ten feet away, and I compare the results of both monitors several times during the day.

When I have the ceiling fan on low speed, gently stirring the air, the readings from the two sensors are usually within 3% or so. But, I am amazed at the CO2 bubble that is created when I don't have the ceiling fan running. The difference can easily reach 30%, and in a well sealed house, this could mean local CO2 concentrations sufficient to cause discomfort, irritability and even reduced mental functioning.

So what I'm seeing not only points to the need for fresh air and the need for HRV, but additionally to the need for air movement.

If we have a central air system, this takes care of dispersing any local CO2 bubbles , but if we're going for mini-splits or even more so, radiant heating in a well sealed house, some gentle stirring of the air would be to our benefit.

-AC

03-23-13, 03:16 PM	#74
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	'CO2 Bubbles' in Still Air... It is interesting how instrumentation can give us an awareness of previously unseen things. My desk is set at a wall, facing out through a window. I generally do my Internet work there as well as small electronic projects, such as my CO2 sensor. Having a CO2 monitor on my desk now for several weeks has been a real awakening to the CO2 bubbles we create around ourselves if we are in still air. I know this because I have another CO2 monitor hanging on the wall about ten feet away, and I compare the results of both monitors several times during the day. When I have the ceiling fan on low speed, gently stirring the air, the readings from the two sensors are usually within 3% or so. But, I am amazed at the CO2 bubble that is created when I don't have the ceiling fan running. The difference can easily reach 30%, and in a well sealed house, this could mean local CO2 concentrations sufficient to cause discomfort, irritability and even reduced mental functioning. So what I'm seeing not only points to the need for fresh air and the need for HRV, but additionally to the need for air movement. If we have a central air system, this takes care of dispersing any local CO2 bubbles , but if we're going for mini-splits or even more so, radiant heating in a well sealed house, some gentle stirring of the air would be to our benefit. -AC __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker...