We have two hot water heaters in our house; one is in the attic and one is in our crawl space. We have a sulfur smell coming from the crawl space hot water heater, but the water smells fine coming from the attic hot water heater. Our cold water smells fine throughout the house, so we don't think the well water is the issue. The smell seems to be isolated to just the hot water heater in the crawl space. Any suggestions as to why one hot water tank would smell even though the other hot water heater smells fine?
Your crawlspace Water Heater's Anode Rod is shot. This can be replaced at minimal cost compared to a new water heater by a plumber or HVAC guy or by you with some good straining on a long breaker bar...AFTER the Water Heater's been turned off, de-pressurized & very slightly drained.
Solid or Segmented Anode Rods, depending on "ceiling" clearances, can be obtained at Home Improvement or Plumbing Supply places. If one Water Heater went the other could be close behind & should be done as well, since checking it is the time to just replace it. There's nothing wrong or bad about replacing it too soon.
The sulfurous hot water heater may have sulfate-reducing bacteria in it. These are typically removed by chlorinating the heater tank and its associated lines. Switching the anode inside from magnesium to aluminum (if applicable) is also suggested online; water reacting with a magnesium anode, if present, is more likely to make the H2 that the bugs live off. But don't ditch the anode entirely, as the reaction can also occur on the steel innards of the tank if they're exposed (and the steel innards will now begin to corrode, which the anode is supposed to prevent).