On Dec 28, 9:17*pm, "bob" wrote:
How much would it cost to scan? I believe you can rent one online, or buy
one for US$1600.

Or try using smoke? Use an incense or something similar. If there's a draft,
it should be easily detected. Another idea is to create a negative pressure
in the house (e.g. by turning on a strong exhaust fan or window fan). This
would make the draft stronger and easier to detect

Harbor Freight has a $19.99 and a $25.99 unit (coupon for this one).
I got one a week ago, only thing I don't like is the laser pointer
points below the hot spot, but as long as I remember that, it has been
fine.