A method of heating a chemical solution used in a well bore having a tubing string is disclosed. The well bore will intersect a hydrocarbon reservoir. The method will comprise providing a diesel engine that produces heat as a result of its operation. The engine will in turn produce a gas exhaust, a water exhaust, and a hydraulic oil exhaust. The method would further include channeling the exhaust to a series of heat exchangers. The method may further include flowing a treating compound into the heat exchangers and heating the treating compound in the series of heat exchangers by heat transfer from the exhaust to the treating compound. The operator may then inject the treating compound into the well bore for treatment in accordance with the teachings of the present invention. One such method would be to inject utilizing a coiled tubing unit. The novel thermal fluid heating system is also disclosed.