Retro-FM ®

Retro-FM is an advanced, tubular self-regulating heating cable system that is used internally for efficient and reliable pipe freeze protection in pressurized applications of 230PSI or less. Retro-FM is a patented and unique conductive tubular system designed to provide internal freeze protection for existing, problematic, pressurized sewage and grey water force mains and large diameter pressurized potable water pipes without the need to excavate. The Retro-FM is supplied job-ready with a 1-inch non-metallic MIP fitting and a 1 inch FIP X 2 inch MIP PVC bushing complete with a 120 or 240 volt direct plug and in-line GFI (GFI models only), no additional electrical work is required.


Retro-FM is the only trace heating system designed to internally protect pressurized sewage and grey water pipes as well as large diameter potable water supply pipes. These applications include but are not limited to rural and municipal sewage force mains; commercial/industrial potable water supply pipes and other similar applications.

The Retro-FM freeze protection system is a job-ready, pre-assembled system that provides safe and reliable freeze protection of pressurized pipes. Applications include but are not limited to sewage or waste water force mains and large diameter potable water supply pipes. It is compatible with all pipe types including all metallic and non-metallic materials. The Retro-FM is suitable for installation in pressure applications to a maximum of 230 PSI.

The Retro-FM is manufactured using a pre-determined length of Heat-Line’s advanced, self-regulating heat tracing cable, factory installed inside a ½ inch HDPE tube finished with a proprietary fusion end-seal. The purpose of the HDPE tube is to provide a barrier from fluids while providing extremely efficient heat transfer. The Retro-FM system will easily push inside most pipes for distances up to 150 feet (46m) and in some cases greater. For distances greater than 150 ft. (46m) the Retro-FM can be drawn in with a plumbing/ electrical fish tape or rope. The Retro-FM is supplied with a 1 inch non-metallic MIP fitting and a 1 inch FIP X 2 inch MIP PVC bushing to quickly interface into force main tee and wye fittings.

The versatile interface process of the Retro-FM makes the system suitable for installation in pipe diameters 2 inches and greater. In large pipe applications, Retro-FM is designed to provide a melt-water path, thus allowing continuous flow through the entire channel. This allows the fluids to carve their way through large diameter pipes without having to install energy-expensive high watt density heat tapes.

Even in applications where the pipes are intended to be dry for short or extended periods of time, the Retro-FM presents no danger of overheating or melting the pipe, making it suitable for all metal and non-metal drain lines that do not always contain liquids.

Retro-FM can be used as a system to prevent freezing or as a precautionary system to use only if a freeze-up occurs. The Retro-FM is a fully serviceable product. If a blockage occurs, the entire heat system can be removed and re-installed.

Retro-FM employs the unique and advanced performance of self-regulating electrical heat tracing technology. Constructed of self-regulating heating cable technology the Retro-FM can effectively increase heat and energy output microscopically along its length to points which are cold and simultaneously reduce heat and energy output to areas which are warm. You never have to worry about the Retro-FM heating cable overheating causing risk of melting and fire because of the self-regulating heat trace cable technology. Retro-FM gives you the peace of mind of reliable freeze protection without the risk. It has become an essential product for homeowners, engineers and building maintenance professionals to provide safe and reliable freeze protection in specialized applications.

To further increase the energy efficiency of your Retro-FM heating cable system, it is recommended to add thermal insulation and a thermostat. The additional thermal insulation works to reduce heat loss, and the thermostat allows you to duty cycle your Retro-FM system based on external pipe temperature. Both accessories combined can increase energy efficiency by as much as 80%.

For non-pressurized pipe systems such as sewage drains and large culverts, please see Retro-DWS.

For new or exposed pipe systems also see EXT5R systems.

Retro-FM is an internal heat tracing system designed to provide reliable freeze protection of metallic and non-metallic pipes. Examples include but not limited to;

  • Existing/ New sewage, septic and effluent pipes
  • Existing/ New commercial/industrial potable water supply pipes
  •  Existing/ New high-pressure fluid lines
  •  Existing/ New pressurized storage and holding tanks

Retro-FM can be found providing freeze protection in many of the following places:

  •  Rural Septic/ Sewage Homes and Cottages
  •  Large Residential and Commercial Potable Water Supply Pipes 2 inches ID or greater
  •  High Pressure Fluid Lines Maximum 230PSI
  •  Commercial/ Industrial Buildings
  •  Municipal Water Main Supplies

As Retro-FM is a unique, high-quality product, it can be utilized in many specialized applications. If you feel you have a special or unique application for Retro-FM please contact Heat-Line directly and speak with one of our knowledgeable product specialists.


  • 5 year limited warranty, 10 year extended warranty available
  •  Can be installed inside metallic and non-metallic pipes
  •  Provides reliable freeze protection for many pipe diameters
  •  Easily and quickly installed on most existing pipes without their removal
  •  Will never melt or burnout the pipe, even if the pipe is dry
  •  Can be fully insulated to increase energy efficiency
  •  Can be used with various control devices including timers and thermostats
  •  Ease of installation can be pushed in up to 150 ft. (46m) and sometimes greater
  •  Long systems can be drawn in with electrical or plumbers fish tape or rope
  •  Suitable for above ground applications when properly insulated
  •  No need to excavate below the frost line, thus saving costs on installation
  •  Can fit existing pipes 2 inches ID and greater
  •  Available in 10ft. (3m) increments to a maximum length of 540ft. (165m), custom lengths are available


  • Patented for North American market
  •  cCSAus approved (Canada and USA)
  •  Manufactured in North America
  •  Self-regulating/conductive polymer heating cable
  •  Certified for operating system pressures up to 230PSI
  •  Made of chemical resistant HDPE
  •  Most reliable and energy-efficient system on the market Proven performance in cold climates (even in above ground applications)
  •  Completely serviceable, remains in place without downward end being secured
  •  Supplied job-ready, no additional electrical work required
  •  Supplied with non-metallic 1″ MIP staged fitting and 1″ FIT x 2″ MIP PVC bushing to quickly interface into force main tee fittings
  •  20 ft. (6m) power supply lead standard on both GFC and CS Models
  •  Ground fault protection is integral to the system (GFC models only)
  •  Simply plugs into a 120V or 240V receptacle (GFC models only). No extra electrical work is required
  •  Cord set (hardwire) connected Retro-FM models available upon request
  •  No other product combines these features or offers the reliability and flexibility


  • cCSAus approved (Canada and USA) LR85446
  •  cCSAus NSF/ ASNI 61 Certified for Potability
  •  Usage P and X Canada
  •  Installation Type A USA
  •  Certified for pressure systems operating at a maximum of 230PSI

Electrical Specifications

  • Self-regulating/conductive polymer tubular heater
  •  120 Volt systems – 5 watt /ft. (15W/m) at 50°F (10C), maximum length 230 ft. (70 m)
  •  240 Volt systems – 5 watt /ft. (15W/m) at 50°F (10C), maximum length 540 ft. (165 m)
  •  GFC models – 20 ft. (6m) power supply lead with 27 milliamp ground fault circuit interrupter plug-in device
  •  CS models – 20 ft (6m), 12-14 AWG SJEOOW supply cord for direct hardwire connection, GFCI must be field installed

Plumbing Specifications

  • Certified for pressures up to 230PSI
  •  ½ inch ID chemical resistant HDPE
  •  1 inch non-metallic MIP staged fitting for connection
  •  1 inch FIP X 2 inch MIP PVC reducing bushing
  •  Minimum internal pipe size required is 2 inch ID

Measuring Recommendations for Retro-FM

Always measure prior to ordering, do not assume or estimate the length required.

– The Retro-FM is an advanced internal self-regulating tubular heating cable system factory finished and supplied job-ready to a pre-determined length provided at the time of order.

– Retro-FM systems are priced in standard lengths of 5 ft. (1.5m) increments up to 100 ft. (30m), then in 10 ft. (3m) increments from 100 ft. to 540 ft. (30m – 165m).

Important Notes:

-A Retro-FM system can never be lengthened. If a longer system is needed an entire new system would be required.

-A Retro-FM system can never be cut shorter at the job-site. If a shorter system is needed it must be shipped back to Heat-Line to be shortened.

– While most Retro-FM systems are manufactured in standard lengths, special lengths of any measurement can also be requested within the maximum lengths allowed. For example, if an 18ft. (5.5m) system was required, instead of purchasing a 20ft (6m) system, a special order could be placed for an exact length of 18ft (5.5m).


– It is important to remember when measuring that the intention is to provide freeze protection along the entire section of the pipe or force main that is in danger of freezing. For example, in the diagram below the Retro-FM interfaces with the force main effluent pipe in the pump chamber and then extends all the way to the leech field, in most cases ending at the distribution box.


Retro-FM Effluent Pump Chamber to Leech Field Install

– In applications where the existing problematic, pressurized sewage and grey water force main and or large diameter pressurized potable water pipe is exposed and above ground, the simplest method of measuring is with an external measuring device such as a measuring tape and/or flexible ruler.

– In applications where the existing problematic, pressurized sewage and grey water force main and or large diameter pressurized potable water pipe system is buried it is beneficial to internally measure the length of heating cable required with an electrical or plumbing fish tape.

As in all cases, if you are unfamiliar or uncomfortable with the measuring and or installation of a Heat-Line product please consult directly with a Heat-Line application specialist or contact a qualified local tradesperson.

Retro-FM is a custom order product however in most cases it can be shipped out within 3 days from the time of order. Please call for current availability and lead times.


Included in a Retro-FM system:

  • Factory finished, self-regulating heating cable set installed in ½ inch HDPE polyethylene pipe in pre-determined length
  • 120/240V GFC models: 20 ft. (6m) power supply lead with built-in 27 milliamp ground fault circuit interrupter plug-in device
  • CS models: 20 ft. (6m), 14 AWG SJEOOW supply cord for direct hardwire connection, GFCI must be field installed
  • 1 inch non-metallic MIP staged fitting
  • 1 inch FIP X 2 inch MIP PVC reducing bushing
  • 5 year limited warranty
  • Clear, concise installation and support documentation


Retro-FM Accessories

HLA-120120V plug-in thermostat (GFC)
120/240V hardwire thermostat with GFCI (CS)
TIMER-120P120V plug-in timer (GFC)
TIMER-240P240V plug-in timer (GFC)
120/240V hardwire timer (CS)
MA-10120/240V GFCI/ELCI (CS)
INSUL-2.00Insulation sleeve for 2 inch ID pipe (2 5/8 inch ID, 6 ft long)
INSUL-3.00Insulation sleeve for 3 inch ID pipe (3 1/2 inch ID, 6 ft long)
INSUL-4.00Insulation sleeve for 4 inch ID pipe (4 1/2 inch ID, 6 ft long)
HLP-TAPETape for insulation sleeves (100 ft)
INSUL-FOILAluminum bubble foil insulation (16 in wide, sold by the foot)
INSUL-TAPEAll weather Aluminum foil tape (150 ft)
WARRANTYExtended 10 year limited warranty


Retro-FM Product Code Guide

Retro-FM Product Code Guide


Q – What is the difference between Retro-FM and Retro-DWS?
A – There is no operational difference in efficiency but the Retro-DWS is designed for non-pressurized systems where the Retro-FM is designed for pressurized applications. The Retro-DWS fittings are suitable for non-pressurized pipes and GFC models are supplied with a 4 ft. (1.2m) power supply lead. Retro-FM is supplied with a male adapter fitting for use in pressurized pipes with pressures as great as 230PSI and supplied with a 20 ft. (6m) power supply lead.

Q – What is the difference between Retro-FM and Retro-Line?
A – Retro-Line is an approved system for internally heat tracing potable water supply pipes and sump pump lines. The Retro-Line product is not approved for use inside grey and or black water lines, and is only suitable for pipes sizes up to 2 inches ID. The Retro-FM is an approved system for internally heat tracing potable water supply pipes greater than 2 inches ID, as well as grey and black water lines.

Q – Can I use Retro-FM for a sump pump line?
A – Although Retro-FM would be suitable for use in residential sump pump lines, Retro-Line is recommended as it is also suitable and is a more cost-effective solution. However, if you have a sump pump discharge greater in diameter than 2 inches ID the Retro-FM would be a viable solution.

Q – What length of Retro-FM will I need?
A – The length of Retro-FM heating cable that will be required can change from application to application. In most applications, the entire pipe length is protected to prevent any chances the pipe could freeze.

Q – What do I do if I have extra Retro-FM heating cable?
A – Care should be given when determining product length required as the Retro-FM system cannot be shortened in the field. If you have a Retro-FM that is too long contact Heat-Line to speak with a product specialist for further details.

Q – Can Retro-FM be cut if too long?
A – No. The Retro-FM system manufactured by Heat-Line is a pre-assembled factory terminated advanced self-regulating heating cable system that is not designed to be field terminated and or tailored to length.

Q – My Retro-FM system is too short; can I add a small section onto the end? If not, what can be done?
A – No. The Retro-FM system manufactured by Heat-Line is a pre-assembled advance self-regulating heating cable system that includes a proprietary end-seal termination. As such the Retro-FM system cannot be spliced together or altered in the field. If a greater length of the Retro-FM is required you may purchase a single continuous product of the proper length, and or relocate a second power source and install an additional Retro-FM system to complete the required freeze protection.

Q – Is there a maximum length of Retro-FM heating cable systems?
A – Yes. The maximum circuit length of Retro-FM that is allowed on a 120V circuit is 220 ft. (67m), and 540 ft. (165m) on a 240V circuit.

Q – Where do I purchase the Retro-FM heating cable system?
A – The Retro-FM heating cable system manufactured by Heat-Line is available directly through Heat-Line and or any of our Heat-Line product distributors. For a list of Heat-Line product distributors in Canada and the United States please contact Heat-Line directly on our toll-free number at 800-584-4944.

Q – Does a 240-volt system use less power than a 120-volt system?
A – No – Energy efficiency has nothing to do with the designated voltage. We pay for the energy in watts, not in volts. Years ago, the term more efficient was attached to 240 volt systems because you can put more load or amperage on a 240 volt circuit. Unfortunately, the term more efficient somehow became misinterpreted to mean more energy efficient which is not the case.

Q – Can I (the homeowner) install Retro-FM?
A – Heat-Line provides proper and easy to follow installation instructions with all of our products, and offers market-leading technical support. As a result, most Heat-Line systems, including Retro-FM can be installed by homeowners; however, Heat-Line commonly recommends that a qualified tradesperson complete the installation process

Q – How much power does a Retro-FM consume?
A – All Heat-Line brand systems including Retro-FM employ Heat-Line’s advanced self-regulating heating cable technology which operates to deliver energy and heat output to areas of the pipe that are cold and reduces energy and heat output to areas which are warm. While the overall amount of energy consumed depends on multiple factors you can be assured that you are installing the most energy-efficient heating cable system available. If you would like to reduce your energy consumption further you can investigate the addition of a thermostat, timer, and or other control device.

Q – Is Retro-FM safe for use with plastic pipes?
A – The Retro-FM system is safe for use with all metallic and non-metallic pipes. The advanced self-regulating technology employed in the Retro-FM product renders it safe on plastic pipes even when dry as it can never overheat and damage the pipes.

Q – Does the Retro-FM come with a thermostat?
A – A thermostat is not included with the Retro-FM product as they are not required for proper and safe operation; however, a thermostat can be purchased as an additional accessory. Depending on system applications, or where automatic operation is preferred, a thermostat can be used to switch the system on and off to help conserve power or to duty cycle the system. When combined with insulation thermostats can substantially increase energy efficiency.

Q – Do I have to use insulation with the Retro-FM system?
A – Insulation is highly recommended when using the Retro-FM system, especially if the installation is above ground in ambient outdoor air. Insulation helps reduce the overall heat loss and therefore reduces the amount of energy the Retro-FM heating cable must consume. If the pipe is already buried, there is no need to dig up and expose the pipe to apply insulation.

Q – What type of insulation should I use with the Retro-FM system?
A – Heat-Line recommends to use insulation that is best suited to the environment in which it is going to be installed. A common type of insulation employed with Retro-FM heating cables is fire resistance waterproof pipe foam insulation sleeves.

Q – Does the unit shut off when not required?
A – No. Retro-FM self-regulating heating cable systems increase heat output with cold but more importantly, decrease heat output with warmth. As a result, Heat-Line brand products are very energy efficient to operate, but do not completely shut off as they can only idle their output to a minimum amount. To completely shut off the system it must be unplugged or installed with a thermostat. Heat-Line brand systems should be unplugged or shut off when not required (summer months) and tested each year before use.

Q – If the power fails, do I have to reset the unit?
A – Heat-Line products including Retro-FM are designed to turn back on as soon as the power to the unit is supplied. Once re-energized the Retro-FM system has the ability to increase its output to immediately begin to defrost any section of the pipe that has or was close to freezing during the power outage.

Q – What is the indication light on the GFCI on Retro-FM models for?
A – The indication light located on the GFCI device included with all GFC model Retro-FM systems verifies that power is provided to the GFCI device and that the GFCI is allowing power to pass through to the heating cable device.

  • Retro-FM Brochure
  • Retro-FM Catalogue
  • Retro-FM Manual
  • Retro-FM Application Diagram


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