I am posting this topic in case someone out there has this problem or may have it in the future, this is great to know, and few do. Last year I installed two Geo units, these replaced old AC units, but I left my oil system intact, it is a Hydro air system, meaning in each air handler there is what amounts to a radiator that gets hot water from a oil fired boiler for heating the house with hot air. The hot water on the old system is a Amtrol hot water maker, it has a heat exchanger built in and also gets its hot water from the oil boiler. When I installed the Geo's I needed a hot water heater that did not need the boiler to be on, so I installed a basic GE 80 gallon electric water heater. after several weeks of using the new GEO. units and the electric hot water heater, I started getting small whiffs of sulfur (rotten egg) when taking my morning showers. Over the next month the odor from the hot water grew worse and by spring my wife and daughters were ready to take showers with bottled spring water. This was my assumption, I use about 24,000 gallons of water every 3 days for my heating system, this water goes back into the soil close to where my 90 foot well is ,the water level in my well is down 40 feet from the top, so I figured the water was picking up the sulfur mineral and my electric hot water heater was causing the sulfur to come out of the water and stink. This summer I switched back to oil for hot water, smell gone , I figured the low temperature of the heat exchanger in the Amtrol unit did not cause the sulfur to be released. Ok I turned off the oil and turned on the electric water heater along with the geo units two weeks ago and the oder was much, much stronger. Smelling the oder made me madder then the fact that when I went to turn on the breaker for the water heater I found it already on, the wife threw it by accident, four weeks earlier. I started looking on the internet for systems for controlling or mitigating sulfur in well water, I found lots of expensive chlorine adding machines and such. I tried a Google search for hot water smells like rotten eggs and found a this old house forum, someone asked the question why does my hot water stink, several questions were asked of the poster like, does cold water stink, answer no, is it a new water heater, answer yes (about a month old), same symptoms as mine. The response was "you have a bacteria growing in the water heater, it feeds or is caused by trace amounts of sulfur reacting with the water heater's sacrificial anode rod, FIX IS TO REPLACE MAGNESIUM ANODE WITH AN ALUMINUM ANODE and put some bleach in water heater for a couple of hours and you will be fixed. It worked I now have no oder at all, I felt posting this was worth it if even one person ever gets to benefit from it.