Mueller Model D Fre-Heater Installation and Operation Manual
Effective March 1, 1993
Part No. 8800430
Revised November 6, 2019
1.1
DESCRIPTION OF THE SYSTEM
The Mueller® Model “D” Fre-Heater® is designed to recover heat removed by refrigeration or air conditioning
systems. It is a de-superheater that removes most or all of the sensible heat from the compressor’s hot discharged
gas and uses the existing condenser to remove the remaining heat to condense the refrigerant.
Model “D” Fre-Heaters are CSA-listed, fully insulated, double-wall heat exchangers that can operate on any potable
water supply. All Model “D” Fre-Heater water tanks are rated for 150 psi working pressure and are fitted with two
corrosion protection anodes. Refrigeration circuits are rated for a maximum working pressure of 426 psi.
Mueller DE-120 Fre-Heaters have one 240 VAC, single phase, 4,500-watt electric element located in the upper
portion of the tank. The placement of this element allows for maximum utilization of the refrigerant heat recovery
system and minimizes the usage of electricity in directly heating the water. An alternate 6,000-watt electric
element is also available.
The outer jacket of a Model “D” Fre-Heater is corrosion-resistant stainless steel that will remain bright and rust
free with a minimum of care. In coastal areas where the air contains a high salt content, the bright appearance of
the Fre-Heater can be maintained by rubbing it with oil or a light grease as soon as it is installed. Abrasive cleaning
materials or compounds should not be used on the outer jacket, as it may scratch the surface.
IMPORTANT: Fre-Heaters are not normally suitable for use on capillary tube refrigeration systems.
Fre-Heaters are not intended to and should not replace normal air- or water-cooled condensers.
1.2
TECHNICAL SUPPORT
This manual provides basic installation and operating information to ensure safe and optimum performance of
the Mueller Fre-Heater. Please contact your local Paul Mueller Company Sales and Service Representative if you
require additional technical assistance pertaining to installation or operation procedures.
Manufacturer’s support is available by contacting:
Paul Mueller Company
1600 West Phelps Street
Springfield, Missouri 65802
Direct Telephone: 1-800-756-5991
Facsimile: 1-800-436-2466
Email: [email protected]
1.3 CAPACITY
The Model “D” Fre-Heater is designed for use with air- or water-cooled condensing units. The size of the units and
refrigeration systems on which each model may be used are shown in Table 1. Dimensions of the various models of
Model “D” Fre-Heaters are shown in Figures 1 to 4.
The amount of hot water Model “D” Fre-Heaters generate will vary, depending on the running time and the size of
the refrigeration system.
1
Section 1.0 – Introduction
