My water heater does not seem to reheat sitting water. I've read about broken dip tubes and thermostats, but neither really explain the problem I'm having. If I wash the dishes or fill the bath with hot water, the water heater will immediately come on. The water appears to heat to the proper temperature at that point, so I think the thermostat is OK. There is usually enough hot water for two baths/showers so I think the dip tube circulates the new cold water properly (unless I'm misunderstanding its use). If no large amount of hot water is used (such as a shower), the water will continue to get cooler until my 'hot' water becomes lukewarm. If I run a bath and wait fifteen minutes, the water heater will come back on and heat things up to the proper temperature. Is there any known explanation for this? My water heater is four years old. It was installed when my house was built (four years ago) and has been this way for as long as I can remember.

Hi, I have a section of 2" Cast Iron Sink Drain Pipe in my cellar,wich is rotting through and leaking.I want to cut out the bad section,and put pvc in its place.Can I cut through this with a SawZall?What type of blade works best? Also what type of connections do I ask for at the store to go from PVC to Cast Iron?Thanks.