Was at house today with a pellet insert running upstairs in the living room and a pellet stove running in the basement. I set up the Magnehelic gauge and it was pushing .80 WC in the basement and nearly 2.31 WC upstairs. YIKES! I asked the customer if her or him (the husband) was irritable or augmentative all the time and the answer was yes... So is the life of folks living in a "sick house" constantly under negative pressure....OAKS are important.