Fire crews from Bracknell and Wokingham called to reports of a conservatory fire in Fletcher Gardens, Binfield, at about 7.30am.
By the time firefighters reached the home the owner had doused the fire down with water.
A hose reel was used to fully extinguish the blaze before it could spread to the rest of the house.
Firefighters believe the heater could have experienced an electrical fault after it was left on standby.
No-one was hurt.