Swamp cooler pads: swap them in April, not June, and you will feel the difference
I put off changing the pads on my swamp cooler until the first hot week last June and my power bill hit $186, which is about $40 more than the same month a year before. When I finally climbed up there, the old pads were crusted solid with our hard water and dust, so the thing was basically blowing hot air around. I swapped in new aspen pads in mid April this year and the house stayed cool through the first 90 degree days, so does anyone else up here have a set month they do this, or am I the odd one?
Wait, you're swapping pads because you want to save money? I just do it whenever the air starts smelling like a wet dog, which for me is usually July. April seems early, the pads just sit there getting dusty before you even need them.