Lennox FCM 85 Installation, Operating And Maintenance Manual page 49

VENTILATION : AIRFLOW BALANCING
AT15-15G2L(*)
(*) The performances of twin fan units can be calculated starting from the corresponding operation point for a single fan
(see the figure behind) by applying the formulas below.
- pressure : PTwin = P x 1
- volume flow rate : Qb = Q x 2
- impeller power: Wb = W x 2,15
- fan speed : Nb = N x 1,05
- Lws : Lwsb = Lws + 3 dB
FLEXYII_WSHP-IOM-1307-E - 47 -