Model D Fre-Heater® Heat Recovery System

No matter the size of your dairy operation, you need ample hot water. With the Mueller Fre-Heater® you can capture the heat from the milk and inject it back into your potable hot water system. Depending on your dairy cooling system and the amount of your dairy production, 100 percent of your hot water needs can be supplied by a Fre-Heater. 

Through these systems Mueller encourages sustainability by recycling the heat generated from the tank-cleaning process and using it to fill the hot water heater.

With our dual jacket, there are no concerns about refrigerant leakage and our industrial-grade, fully-insulated, glass-lined storage tank assures potable water and minimal heat loss.


  • Stainless steel outer jacket. Rust resistant exterior requires no maintenance.
  • Mueller Temp-Plate heat transfer surface cools the super-heated refrigerant from the milk cooling condensing units and harvests the system’s wasted heat energy.
  • Industrial-grade, fully insulated, glass-lined storage tank assures minimal heat loss and long-term reliability.
  • Factory-installed anode(s) provides superior galvanic corrosion protection for the water storage tank. Model D-120 has 2 anodes, and Models D-50 and D-80 each have 1 anode.
  • Five-year limited warranty protects your purchase.
  • Complies with CSA regulations for the United States and Canada.

Specifications and Sizing

Model No. Part No. Water Connection (in) No. of Refrig. Circuits Refrig. Connection Size (in) Per Circuit Refrig. Application Capacity* Height (in) Diameter (in) Approx. Shipping Weight (lb)
D-50 8823750 ¾ MPT 1 .625 OD .5-4 ton R-22/507 53.875 21.75 234
D2-50 8823751 ¾ MPT 2 .625 OD .5-4 ton R-22/507 53.875 21.75  234 
D-80 8823780 ¾ MPT 2 .75 OD 1-5 ton R-22/507 58.625 25.25  310 
D-120 8823821 1½ FPT 2 .75 OD 1-7.5 ton R-22/507 61.75 29.5  446 
D2-120 8823820 1½ FPT 2 1.125 OD 3-15 R-22/507 61.75  29.5  446
DH-120 8823823 1½ FPT 2 1.625 OD 7-35 ton R-22/507 61.75 29.5  446
DHS-120 8825141   1 1.625 OD   61.75 29.5 446
DE-120 8823822 1½ FPT 2 1.125 OD 3-15 ton R-22/507  61.75  29.5  446

*Refrigeration tonnage capacities are 30°F evaporator ton loads, not total heat of rejection tons. Pressure drop through a Fre-Heater refrigeration circuit will be approximately 15 psi at the maximum tonnage application. Pressure drop at the mid-range of tonnage application will be approximately 5 to 7 psi. The best overall refrigeration/heat recovery system efficiency is usually obtained at or below the mid-range tonnage application.


Finding the right equipment that fits within your budget can be daunting. At Paul Mueller Company, we understand your needs. That’s why we offer Leasing options that give you more flexibility.

Tell us more about your needs.

Our Dairy Farm Partners

We are proud to partner with these leaders in the dairy farming industry. From legacy farms that have thrived through multiple generations to solar cooling in Africa that is providing young children their first taste of cold milk, our equipment is impacting lives around the world.