My thoughts are your coop may go up in flames.
For the vast majority of climates, heating a coop is completely unnecessary and dangerous.
Additionally, if they suddenly lose the heat source, the chickens will be subjected to high stress levels/inability to cope.
The goal for keeping chickens healthy during winter is to keep them DRY with no drafts on them when roosted to keep their feathers from blowing open and releasing their trapped body heat.
That means LOTS of ventilation to permit cold, dry air to enter down low and moist, stale, warm air to leave up high along with having dry bedding, removing the nightly poop load and keeping all water sources closed if kept in the coop.