Just for giggles I checked and over the past hour my return flow* has varied from 1,278 GPH to 1,285 GPH. Delta of 7 GPH? I can live with that!
I could see substantially more variation in a drain line though...
M
*FWIW, using a 2" Neptune flow meter in a 1-1/2" return.
I could see substantially more variation in a drain line though...
M
*FWIW, using a 2" Neptune flow meter in a 1-1/2" return.

