Edwin Pawlowski wrote:
I don't know the answer to your present problem, but . . . . .

If you have three zones of heating, wouldn't it be better to have
each zone
controlled on its own? Why not call in a pro and see what can be
done.
Overall it will save you money if you can keep the unused areas of
the house
a bit cooler.

Yes it would. However, when we originally called someone in last year,
the cost to fix the other two components to get them firing correctly
was quoted at roughly 20% of a new system. We're not sure whether we
want to keep this current system and our timeline is 4-5 years for that
decision (and more importantly, budget availability). So, we decided
to bide our time until the budget was available and in the interim, add
insulation, and do other fundamental things before deciding on fixing
the current system, upgrading or resizing it to meet the enhanced
characteristics the insulation and other things provide, or overhaul
the current system and replace with heating and cooling.

In the interim, given our house configuration, managing temperature
from the middle zone seems to naturally regulate the other levels. We
use our lowest level less frequently than the middle level and we sleep
in the upper level, which benefits from the natural rise of the heat
and we use the prog t-stat to allow the temp to drop at night.

Would it be even more efficient to revamp the system for 3 zone
control? I don't know. However, I'm hesitant to put that type of
investment in an old system that may only be in place a couple of
years. Given this situation, we may be forced to acquire more quotes
and bite the bullet.

Dave