Heating service. After diagnosing the home's boiler system, I found that customer has two thermostats, one thermostat controls the air handler in the attic, and the other thermostat directly below controls the boiler in the basement, she turned off the thermostat that controls the air handler, thinking that it was the boiler thermostat turning off and it wasn’t therefore the boiler Kept heating the house when she thought she turned it off. I explained everything to the customer on how to use the thermostats and which one controls which again again, I showed her that the boiler is off when I said it 1° below what it is in the home And that it turns on and off just fine. Did not change any parts. Thermostats are working correctly.