I live in a large, multi-apartment building in the northeast with a cooling tower on the roof. Each apartment has it own ac/heat unit. Mine is a 7-ton Mammoth Hydrobank.

What I find intriguing is that while I am running heat, my neighbor might be running his/her a/c. (Because of heat sources in spaces beneath, this can actually happen in enclosed spaces even when the outside temp is at freezing.)

I hear about systems (mostly in offices) that are "turned off" for the winter. Obviously ours is never turned off as I can use it in both modes at any time during the year.

How is it, that with the flip of a switch, I'm able to go from heating to cooling and back again?

In the heating mode am I consuming as much electricity as when using it for cooling? (We have peripheral hot water heat in the building so the heat function of the air system is used to augment the central heating.)

Someone told me it isn't as costly because I'm running in fan mode, taking the heat from the water circulating in the system, suggesting that the tower is somehow connected to the peripheral heating system. That possible?