On Oct 14, 11:05*pm, wrote:
Live in 60 year old 1300 Sq Ft single story brick house with full *basement,
it has recent 600 Sq Ft addition with about 3' crawl space. Live in Michigan
(zone 5) and winter heating bills are a killer.

Have you installed a setback thermostat yet? Extremely good payback
on that.
And look for cobwebs in the basement. Those spiders find the air
leaks
nicely and identify them well..