the ridge vent wasn't big enough. Second, he said there were no soffit vents.
narrow. How could soffit vents be installed if there's almost no soffit?
Here's some photos of 3 attic fans. The dates on the photos are wrong and not in order due to camera snafus.
Vent from inside attic, before fan installed
I mounted it on 1/4-in plywood first because there was nowhere to conveniently mount it to the studs without blowing air back into the attic.
Fan installed ready for wiring
Fan as installed
Thermostat wiring.
Thermostat as installed. Ended up moving it to a hotter location and setting it at 110 deg F. Was not reliable leaving it mounting in the fan intake. I don't use leave the fan powered -- just use the thermostat to tell me when it's hot enough to run. Also it will shut the fan off in case I forget. But I don't depend on it.
Different vent fan - was too noisy and vibrated off center-- returned
Roof-top fan on a different house - it looked like a space ship on the roof so I painted it with Rustoleum. If you install on of these, be sure you seal it good and slide it up under the shingles properly. I wouldn't install one of these again because of the windy rains we get. Also I don't like cutting holes in the roof.