Bob, ur tab procedure is badly flawed. The manometer would be used as a VERY last resort. That means will get you within 20% - 50% accuracy pending main branch run to the inlet. Flowhood is the simplistic way to determine actual Cfm. The fan powered box where you not nothing to do at the filter inlet point is actually the MOST important point to test. Once correct fan cfm is set you need to match that with primary air to assure getting the 55.0 F leaving temp (Typ) This is done by making sure the filter inlet point is not positive or negative but neutral. Unless you want to draw plenum air at full flow or discharge cold primary air out that point which cost money. Aloha Paul Morse-AABC-TBE
Bob, ur tab procedure is badly flawed. The manometer would be used as a VERY last resort. That means will get you within 20% - 50% accuracy pending main branch run to the inlet.
Flowhood is the simplistic way to determine actual Cfm. The fan powered box where you not nothing to do at the filter inlet point is actually the MOST important point to test. Once correct fan cfm
is set you need to match that with primary air to assure getting the 55.0 F leaving temp (Typ) This is done by making sure the filter inlet point is not positive or negative but neutral.
Unless you want to draw plenum air at full flow or discharge cold primary air out that point which cost money.
Aloha
Paul Morse-AABC-TBE