How long does a water heater take to fully heat up?
Generally about 45 minutes. If your water heater has been turned off or if you have just had a new unit installed it will take approximately 45 minutes to heat the water up. Each water heater varies in recovery depending on the gallon capacity and BTU input, but if after about 1 hour there is still no hot water then the unit is not working properly. Gas water heaters recover quicker than electric water heaters, but either way you should not have to wait more than about 1 hour for a water heater to fully heat and produce hot water.