The cheapest way to heat water around here is to scavenge waste heat from the AC compressor. That gives you free hot water and your AC runs better.
Very good point, I work in very large super markets and any heat that can be scavenged from the refrigeration equipment is used to heat the building and water. This saves money directly by using less fuel to heat and by shortening the run time of the condenser fans.
How is this accomplished with dwelling unit ACs and water heaters?
