I have a solar air heater on my roof and need some help in determining
the amount of energy I am saving.
Cold air from the basement enters 2 sq ft of duct and goes up to roof
mounted heater....it then gets heated and blown back down another 2
sq ft duct to a room in basement that has barrels of water to absorb
and store heat.
I have thermistors in both ducts and am recording temps to an excel
file every 5 minutes...we measured airflow with a handheld anometer
and have determined that we are putting just over 1500 cfm of air
through system when blowwer is operating. Blower is turned on when air
reaches 75° F inside heater.
Q : How close will our cfm calc be compared to the propper "Hood"
measuring procedure and would our measurment typically be higher or
lower than actual?....I found a formula...Kw = cfm x delt t/
2650....delt t in °C......soooo if I had a 10°C delta t for one hour
woul I have produced the heat equivilant of 5.6 Kwh?...since I am
measuring every 5 minutes do I average the 12 temp readings over an
hour or should i multiply each reading by 5/60...(min/hr)...