We've had a similar situation. Without an actual water test, the symptoms make me think it is "iron bacteria." If the system is used daily, the pipes and water heater are flushed well enough so that the smell is barely noticeable. When we are just weekending, it is strong when we first come in, as the water in the system has been sitting for 5 days at favorable temperatures.
What I have been doing recently when we leave after a weekend is to turn off the heater breaker and supply valve to the heater, open the hot water faucets until the dribbles stop, open the drain valve at the bottom (to which is attached a hose connection that runs down and outside), and let the tank drain to empty. It helps to lift the relief valve lever at the top to break suction, although I suspect that ultimately air would flow back from the tub faucet close by to vent the tank. As we leave, I turn off the pump breaker as well.
Coming back in, use of the toilet a couple of times and opening the cold faucet in the tub empties much of the water left in the air tank underneath the house. Then I close the vent and drain valves on the hot water heater, then open the supply valve. It takes a few minutes to refill the tank. When it is full, as indicated by water coming from the hot faucets, I turn the breaker back on to have hot water in the morning.
Evacuating the bulk of the system and letting the normal use of the cold side during restart flush has eliminated the smell.
|