Does this unit allow for a lower heating range?

Yes the GH48R does allow for you to switch to a lower heating range. The manual shows that the heater has two output levels: High: 4,800 Watts or 16,378 BTU at 240V or Low: 2,400 Watts or 8,189 BTU at 240V. If you have any further questions, feel free to give us a call!