I currently have a natural gas furnace and a air-source heat pump. Since the effiecency of a heat pump varies on a number of factors, I would like to find out at what outside temperature does it become more COST EFFICIENT to switch over to my natural gas furnace vs air-source heat pump? I am pretty sure I'm going to have to create a spreadsheet to calculate this. That way when costs change, this would allow the user to know how it effects the outside temperature.
Can anyone help me out or has this already been done before somewhere else?
HeatPump variables HSPF Size of unit (in what measurement?) Outside temperature Inside temperature Cost of electricity
Natural Gas furnace variables Cost of fuel efficiency of unit
Are these the main variables needed? Where can I find the necessary formulas? I really appreciate any help that can be given. If I can figure this out I may be able to put up an online spreadsheet or something. Thank you!!!