If the equipment isn't running all the time, what do these old people do when the equipment shuts off?
Why do they need to "warm" themselves in front of a register?
I think if you step back you'll find the problem is they are keeping the enclosure too close to their discomfort line. Bump the thermostat a couple degrees.
You may want to do this inside the programming so they can "keep the thermostat below 70 and be good Americans" like Jimmy Carter suggested.
I did this for some really nice folks in a 1700 sf mobile home. They're now in their 80's, and 69 is simply too cold.
And the work they did cut their annual gas use from 1050 therms to 625, with no increase in electric. I'd say they're good Americans, and if the house is 72 that doesn't change a thing.