HOS (Hruby Orbital Systems) offers an OP machine that via an onboard heater can produce a heated spray. My own understanding of what I believe is the 2nd law of thermodynamics (heat goes from where there is some, to where there is less) suggests that due to heat losses from evaporation, very little heat would be left in the droplets of spray due to the trip of the heated solution from the tip of the sprayer to the surface of the carpet. This may be why there are no heated sprayers that I know of.

In high dirt-plus-grease situations, I have sometimes brought along a 5-gallon pail and a bucket heater. Drop a terry cloth pad into the bucket of boiling water, or a water-detergent solution, then - using tongs - pull it out soaking wet, quickly place it onto the soiled carpet, then get your OP machine on it real fast so that you can scrub before the heat in the pad dissipates. This has worked best for me when using the 2-sided, 100% cotton Argo pads, probably because their relative thickness holds more heat longer than thinner pads.