The primary result in using the ZoneThermalChimney model is ventilation. It uses solar energy coming in through a window to warm air making is rise and pull air out of a zone inducing ventilation. The diagram below from the Engineering Reference shows its operation:
The InputOutputReference specifically says:
The air within a thermal chimney is
heated naturally using solar energy.
The air increases in temperature which
causes its density to drop. This drop
in density results in a natural
vertical movement of air and a local
drop in pressure. The drop in pressure
is relieved by drawing air from the
building interior, and the heat gained
within the thermal chimney does not
enter the occupied portion of the
building.
Given this description, it does not sound like any of the heat gained in the thermal chimney can be used to heat the space.
You're using the
ZoneThermalChimney
object? Heat gains should be accounted for using that object. Take a glance at the engineering reference here and the input output reference here.