To make sure you're not testing too early, assume the sperm had very long lives (5 days is considered a very long sperm life) and that conception occurred then. Then allow 14 days for the embryo to implant and develop enough hCG to show up on a pregnancy test (96% of pregnant women will test positive by then.)
A gas water heater will recover in half the time of an electric unit. A 40-gallon gas water heater can recover in about an hour. Recovery for a 40-gallon electric water heater takes about two hours.
But replacing a water heater is not extremely hard, and if you follow this tutorial you'll be back in hot water in no time. Well, plan on a good 4 to 6 hours anyway. Selecting Your New Water Heater. When selecting your new water heater it's easiest to keep the same fuel type, whether gas or electric. That is the assumption made in this tutorial, that you'll keep the same fuel type as the water heater you're replacing.