Why is my EPH coming on at night

Hi Robert. I would suggest that what the builders are saying isn't entirely false. Depending on what EPH thermostat you have, some of them will have a pre-heat or an optimum start function. This is when the thermostat learns how long it takes to heat your property to whatever temperature you have set. As the weather changes, the thermostat will automatically update and adjust the amount of time required to heat up. However, if you don't want this function, you should be able to disable it in the thermostat settings. Hope this helps.