got a remote reading thermometer and stashed it in the attic to see
what's happening. now i'm wondering what i should expect.

normalish 50 year old ranch house, connecticut. 1500 sq feet more or
less. old central AC, not particularly powerful or efficient. normal
amount of insulation, i.e. less than would be optimum but normal for
the period. powered vent fan, mushroom style. soffit vents, gable
vents, etc.

on the wise advice proferred here last year, i upped the temp on the
thermostat for the vent fan from 80 degree to about 100 IIRC.

OK; so during the final months of winter, when i had the thermometer,
there was a maximum of about 20 degrees difference between the house
and the attic.

lately, when it's warm, often 20 degrees difference, obviously in the
opposite direction. during a hot spell last week, when it was 90+
outside, attic got up to 120; house got up to 87 (AC off during
daytime).

so, is this reasonable/expected for powered attic vent? would bigger
fan do better?