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What's New: Cain Exhaust Heat Recovery

Updated: Apr 8, 2021

SOLUTIONS CENTRAL | October 2020 |

CAIN EXHAUST HEAT RECOVERY - Boiler Economizer Systems


Exhaust heat from boiler combustion typically leaving the stack and into the atmosphere is instead transferred from the exhaust stream by means of a Cain economizer. This lost BTU is now captured and saved to various heat sinks such as boiler feedwater, cold makeup water, process water, swimming pool water, glycol, and thermal fluids. Combustion source fuel types including natural gas, propane, digester gas, diesel fuel, and No.2-6 fuel oil are all heat sources which can be retrofitted with Cain heat exchangers.


  • Tremendous fuel savings typically pay for equipment and installation within 1 to 2 years of average use.

  • Pollution reduction equivalent to lowered annual fuel usage.

  • Longest heat exchanger life expectancy.


Without Cain Economizer:

  • Most boilers have a combustion efficiency of 78-82%.

  • Boiler exhaust temperatures exiting into the atmosphere: 350º-600º F.

  • Stack energy loss is typically 18-22%.

With Cain Economizer

  • Efficiency is increased, reducing fuel costs. Average efficiency increase is 4-10% (30-50% of the available energy lost).

  • A portion of the stack loss is recovered, and the energy (BTU) is returned to the systems preheated water. Exhaust temperatures exiting to the atmosphere are reduced to 150º-300º F.

  • Economizers operate with virtually no risk or maintenance.

  • Average total turnkey payback: 12-24 months (annual Return on Investment (ROI): 50-100%).


Marlo Coil - Humidity Control Coils


Our Humidity Control Coils solve a common problem in hospitals and other critical environments: excess humidity and condensate collecting on and ruining expensive HEPA and ULPA filters. This single cooling coil recirculates the warm fluid leaving the coil to, in turn, heat and desaturate the air exiting the coil. It requires just one supply and one return header, which saves the significant costs involved with plumbing hot water or steam to a reheat coil. This is a much more cost-effective solution than using both a cooling coil and a separate heating coil to eliminate carryover condensate and moisture, and it can also improve air quality.

PROBLEM: Condensate/moisture carryover collecting on your expensive filters, drastically shortening filter life and reducing the performance of your system.

SOLUTION: New Marlo Humidity Control Coils create a more cost-effective solution to a problem traditionally solved by using both a cooling coil and a separate heating coil.

✔ Eliminates excessive moisture in the airstream

✔ Stops water damage to your expensive filters

✔ Ideal for healthcare and other clean environments

Marlo’s Humidity Control Coils are cooling coils that recirculate the warm fluid leaving the coil to heat and desaturate the air exiting the coil. In addition, these new Marlo coils require only one supply and one return header, allowing customers to save substantial costs associated with plumbing hot water or steam to a reheat coil. And replacing existing coils is easier because Marlo’s Humidity Control Coils use the same supply and return plumbing from the original coil.


  • Use of a common frame and single inlet and outlet header greatly reduce complexities and costs.

  • Having one coil instead of two substantially reduces costs – including installation costs.

  • Adding re-heat circuits on the air exit side of the coil reduces humidity and minimizes carryover.

  • Intermediate drain pans, compliant with indoor air quality standards, further eliminate condensate management problems.

Applications include

  • Hospitals and medical centers

  • Critical care environments

  • Science and research laboratories

  • Manufacturing clean rooms



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