Converted our gas hot water service to a Sanden Heat Pump with the team from NewGen Solar & Heat Pumps a few months ago. That got our HWS off gas and the only thing remaining is the cooktop and heating. As it was winter and the heater was in use it has been hard to really determine how much gas was being saved and how much extra electricity was being used. Typically a HWS accounts for 20% of home energy bills (maybe not our house) and it was expected the heat pump would add an additional 4 to 5 kWhrs of electrical energy. Now that it is summer and the only gas use has been the cooktop it is fairly easy to see the differences. Electricity has indeed increased 4 to 5 kWhr/day but gas energy has been reduced by approximately 80 MJ/day - that is the equivalent of 22kWhr thanks to the efficiency factor of the Sanden heat pump of 5. At $0.32/kWhr for electricity and $0.025/MJ for gas I pay an extra $1.60/day for electricity and save $2/day on gas. Now that is going to take quite a few years to pay off the additional expense (unless I get solar PV) but I will eventually come out ahead and even quicker if gas prices continue to skyrocket. If you are thinking of a new HWS the Sanden heat pump is everything it claims to be and the team at NewGen Solar were a delight to work with.