how do you know what the fraction of the input air is made up of recirculated air?
also, the plastic pipe is not insulated so it will lose some heat to the cooler room.
Yeah, it’s not perfect, and it’s too much trouble to really measure it properly. More complicated than it seemed at first.
However the pipe inlet is about 2/3 the outlet area, and when pointed away from the outlet , has enough suction to pull the flame right off a candle. The air coming out of the pipe is about 28C when the outlet is 31 C, so the pipe is not losing much heat after it warms up. I have been cautious not to pressurize the outlet with the recirculator, which would really make things different from any calibration.
Once it runs for several hours at steady state tonight, I might send 100% of the outlet back in for a short while. That should do something. It has already been running for about 3 hrs so far.
Anyways, I can do some test requests, if anyone has better ideas than what I am doing right now, (which is interesting but probably pointless).