WHALE Gas Only Underfloor Space Heater. For Whale’s heating system range, weight and space saving, practicality and of use and ease of installation are central considerations in this process. The compact, lightweight internal Whale Space Heater range fits neatly inside a bunk or cupboard and is available as a gas only, or gas/electric model. Versatile installation options Gas only or gas/electric versions Space saving, compact, lightweight units Superior insulation, low voltage No wiring, simply plug in Simple & intuitive to use Built in diagnostics system for easy fault finding Improved service access No internal flue or chimney required.