I need help. I had a new home built 2 1/2 years ago. This winter will be the 3rd heating season. Zone 1 is approx. 1200 sq ft. Zone 2 is About 1100 sq. ft. I have 2 split units, one for each zone. Trane 1 1/2 ton unit with an Aquecoil hot water jacket for hydronic hot air. The hot water circulator pump kicks on when the t-stat calls for heating. The contractor installed a cheap clip on aquastat on the supply pipe to the aquecoil to control the fan operation. Here is the problem.......after the stat is satisfied the circulator shuts down...the supply pipe temp drops slowly to open the fan circuit. I can hear it click open, but the fan keeps running for 4 or 5 minutes. This is not a DIY question....i've spoken to 4 or 5 techs, (neighbors and friends on jobs), the contractor who installed the job is MIA. I understand the concept of clearing the heating chamber, one tech said there may be a timer circuit on the fan board in case a a gas furnace is used for heating. When it's 20 degrees out and the registers are blowing cool air for a few minutes it doesn't seem correct. As I mentioned a reward is offered for the first solution that works. Thanks.