Up to 25 firefighters tackled flames and smoke at the detached house in Burnbank, Straiton, through the night.
A man and two children were taken to hospital as a precaution.
Fire crews from Tollcross and McDonald Road initially responded shortly after 8pm.
They arrived to find the fire had spread from the boiler and called for back-up.
Officers doused flames with jet hoses and were on scene until shortly before 8am this morning.
A spokeswoman for Scottish Fire and Rescue Service said: “A male and two children were taken to the ERI as a precaution.”
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