On Thursday, June 21, 2012 5:53:20 PM UTC-4, Dave M. wrote:
There are a number of Chronotherm IV models. Here's the manual for one.
http://homeappliance.manualsonline.c...idRes=15115418
Read the "installer setup" part of the manual.
Find your manual and look for something similar.

Dave M.

Thanks for pointing me to the installer manual. My contractor did not pass that along, so all I have in hard copy is an end-user guide.

However the installer setup table did not address my issue.

Meanwhile, I think I figured it out. Originally, I set a temperature hold and then later, as an afterthought, toggled the fan to On. My intuition was that the fan-on state would inherit the duration of the held temperature. That's apparently not the case. If I toggle the fan on when I set a temperature hold, it seems to stick.