With up to 26,000 BTU's, the vent free technology does not require a flue or chimney. This vent free fireplace system functions on natural gas or propane. With Pleasant Hearth vent free fireplace systems, enjoying the warmth and beauty of a fire has never been easier. Minimum clearance design allows ease of installation almost anywhere. This unit includes thermostat control automatically maintains your desired heat setting . Not for sale in California or Canada. Check your local regulations on installation restrictions and requirements. Propane use requires 20 lb. tank or larger with two-stage adjustable regulator available from local gas company.