Maybe they put in an A/C and wired it as a heat pump. This would bring on the A/C when they want heat. Then they turn it up to 78, and the electric heat stages come on, and they finally get heat. It would use a ton of electricity since the A/C would be cooling while the resistance heat is heating. Leaving it set at a certian temp would cause the A/C unit to never turn off, with the resistance heat cycling at a temp lower than the thermostat setting.