To assist in understanding the basics of heat recovery systems, such as the light commercial/residential Enviro-Pak and the larger commercial industrial Enviro-Temp, Turbotec Products, a world leader in high performance heat exchangers, published a white paper called Heat Recovery from Vapor Compression Air Conditioning: A Brief Introduction, available for download at both the literature section and the Enviro-Pak section of its website.

Heat Recovery Units (HRU’s) operate with air conditioning and refrigeration systems to recycle excess heat which would otherwise be lost, thereby improving overall energy efficiency and yielding useful heating. Other varieties of heat recovery are also possible, such as transferring the heat to a process fluid, like ethylene glycol, and using the heat in industrial processes instead of potable water heating.

The economic benefit is dependent on the cost to recover waste heat versus the cost of generating hot water using conventional means (natural gas, propane gas, fuel oil, electricity, etc.).  The operating cost of the HRU is generally only the electricity to power the circulating pump; less than the average household light bulb (60 watts).  Benefiting from HRU’s can yield an ROI of less than a year to 3 years, depending on location and  the HRU can also assist in reaching LEED goals, reveals the company’s press release.