Retro-DWS ®

(3 customer reviews)

Retro-DWS is an advanced internal self-regulating tubular heat trace cable system that is used for efficient and reliable pipe freeze protection of non-pressurized drain, waste, and sewer pipe applications. Retro-DWS is a unique and patented conductive tubular heating system designed to provide internal freeze protection for existing problematic drains, sewers, culverts, and other pipe systems without the need to excavate. Retro-DWS systems are delivered complete with industry certified plumbing components and Heat-Line’s advance self-regulating electrical heat tracing technology factory installed inside a high-density polyethylene pipe with a proprietary fusion end seal.

Retro-DWS an Internal Sewer Pipe Heating Cable System


Retro-DWS is the only self-regulating heating trace system designed to internally protect non-pressurized drain, storm drain, culvert, waste and sewer pipes. These applications include but are not limited to septic drains, septic tanks, holding tanks and other similar applications where frozen sewer pipes may be a problem.

The Retro-DWS in pipe heating cable is a job-ready, pre-assembled self-regulating system that is a safe and reliable solution for prevention of non-pressurized frozen sewer pipes. This includes but is not limited to storm drains, culverts, waste and sewer pipe systems consisting of all pipe types including all metallic and non-metallic materials. Dealing with frozen sewer pipes on a regular basis will no longer be an issue.

The Retro-DWS is manufactured using a pre-determined length of Heat-Line certified, self-regulating trace heating 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 such as grey and black water while providing extremely efficient heat transfer. The system will easily push inside most pipes for distances up to and greater than 150 feet (46 meters). For long distances, Retro-DWS can be drawn in with an electrical or plumbers fish tape or rope. The Retro-DWS is supplied with certified plumbing fittings to interface with 4 inch ABS pipes using an existing or installed clean-out, Tee or Wye as an access point, with a 3 inch adapter kit available as an add on.

The versatile interface process of the Retro-DWS makes the system suitable for installation in pipe diameters from 3 inches to greater than 8 inches. The Retro-DWS can be easily adapted to fit larger pipe diameters by using readily available, industry standard components. In larger pipe applications, Retro-DWS 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 culverts or drains without having to install energy-expensive high watt density heat trace cables. For large pipe diameters please review Retro-DWS “other methods” in the installation manual.

Even in applications where the pipes are intended to be dry for short or extended periods of time, the Retro-DWS 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-DWS can be used as a system to prevent freezing or as a precautionary system to use only if a freeze-up occurs. The Retro-DWS is a fully serviceable product. If a blockage occurs, the entire heat system can be removed and re-installed.

Retro-DWS employs the unique and advanced performance of self-regulating heat trace cable technology. Constructed of self-regulating heat cable technology the Retro-DWS can effectively increase heat and energy output to sections along its length which are cold and simultaneously reduce heat and energy output to sections that are warm. You never have to worry about the Retro-DWS heating cable overheating causing a risk of melting and fire because of the self-regulating heating cable technology. Retro-DWS 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-DWS 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-DWS system based on external pipe temperature. Both accessories combined can increase energy efficiency by as much as 80%.

Important Considerations

The Retro-DWS is engineered to keep drains from freezing in serious climate conditions. The use of this product and its compatibility with a particular application is at the complete discretion of the user. The Retro-DWS tube may obstruct certain materials, especially solids in gravity-fed drains. As such the Retro-DWS is designed to be serviceable, and Heat-Line recommends a service schedule if there is a concern of impediments.

For pressurized pipe systems such as sewage forced mains, please see Retro-FM.
For new or exposed pipe systems also see EXT5R systems.

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

  •  Existing sewage, septic and effluent pipes
  •  Existing storm drains and culverts
  •  Existing/New septic and holding tanks
  •  Existing/New leech fields and septic beds

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

  •  Lake homes and cottages
  •  Commercial/ Industrial buildings
  •  Septic tanks/ leach fields in northern communities

As Retro-DWS is a unique, high-quality product, it can be utilized in many unique applications. If you feel you have a special or unique application for Retro-DWS 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 in 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 plumbing fish tape or rope
  •  Suitable for above ground applications when properly insulated
  •  No need to excavate below the frost line
  •  Supplied job-ready, no additional electrical work required
  •  Can fit existing pipes 3 inches ID and greater
  •  Available in 10ft. (3m) increments to a maximum length of 540 ft. (165m), custom lengths are available


  • Patented Solution within North America
  •  cCSAus Certified (Canada and USA)
  •  Manufactured in North America
  •  Self-regulating/conductive polymer heating cable
  •  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
  •  Fernco plumbing fittings supplied to ensure connections are simple, secure and leak proof
  • 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-DWS models available upon request
  •  No other product combines these features or offers the reliability and flexibility

Retro-DWS is an innovative solution for the persistent issue of sewer line frozen occurrences. This innovative product boasts a remarkable feature set, beginning with its ease of installation in most existing pipes, eliminating the need for their removal. Unlike traditional methods, Retro-DWS ensures that the sewer line remains unfrozen by delivering reliable performance without risking overheated or melted pipes, even in cases where the pipe is dry. Its unmatched ease of installation allows it to be effortlessly pushed into pipes up to 150 ft. (46m) and sometimes even greater. Furthermore, the system arrives job-ready, eliminating the need for additional electrical work and offering a seamless integration into existing sewer pipes. When you experience the challenge of a sewer line frozen, Retro-DWS ensures a worry-free solution. Never worry about a sewer line frozen again with a dependable solution that prioritizes performance, convenience and efficiency.


  • cCSAus approved (Canada and USA) LR85446
  •  Usage Type W Canada
  •  Installation Type D USA
  •  Internal waste (Grey and Black) water certified

Electrical Specifications

  • Self-regulating/conductive polymer tubular heater
  • 120 Volt systems – 5 watt /ft. at 50°F (10°C), maximum length 230 ft. (70m)
  • 120 Volt systems – 8 watt /ft. at 50°F (10°C), maximum length 150 ft. (46m)
  • 240 Volt systems – 5 watt /ft. at 50°F (10°C), maximum length 540 ft. (165 m)
  • 240 Volt systems – 8 watt /ft. at 50°F (10°C), maximum length 400 ft. (122 m)
  •  120 Volt GFC models – 4 ft. (1.2 m) power supply lead with 27 milliamp ground fault circuit interrupter plug-in device
  •  240 Volt GFC models – 6 ft. (1.8 m) power supply lead with 27 milliamp ground fault circuit interrupter plug-in device
  •  CS models – 6 ft. (1.8 m), 12- 14 AWG SJEOOW supply cord for direct hardwire connection, GFCI must be field installed

Plumbing Specifications

  • Tubular heater constructed of ½ inch ID chemical resistant HDPE
  •  Minimum internal pipe size required is 3 inch ID or greater
  •  Supplied with female Fernco flexible couples to adapt to 4 inch ABS pipe and spigots (3 inch kit optional add on)
  •  Supplied with Nibco 4 inch threaded male adapters SPIG x MIPT for connection to 4 inch ABS clean-outs (3 inch kit optional add on)
  •  Suitable for both metallic and non-metallic piping

Measuring Recommendations for Retro-DWS

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

– The Retro-DWS 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-DWS 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-DWS system can never be lengthened. If a longer system is needed an entire new system would be required.

– A Retro-DWS system can never be cut shorter at the job-site. If a shorter system is needed it can be shipped back to Heat-Line to be shortened or it can be shortened at the job-site by following careful extraction instructions. Always contact Heat-Line for guidance prior to proceeding.

– When measuring the length of an internal heating cable system such as Retro-DWS care should always be taken to ensure that the ordered length is as specific to the exact length as required.

– While most Retro-DWS 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 20 ft (6m) system, a special order could be placed for an exact length of 18 ft (5.5m).


– In some cases, depending on the application you may be able to extend some of the tubular heater into grey and or black water holding tanks (see diagram below) at the end of the pipe run. For the best results when measuring a Retro-DWS application use an external or internal measuring device.

Retro-DWS Waste Pipe to Holding Tank Install

– It is important to remember when measuring that the intention is to provide freeze protection along the entire section of the pipe or drain that is in danger of freezing. The Retro-DWS should interface with the drainage pipe within a heated space in the building and extends into the septic tank located below the frost line.

– In applications where the existing problematic drain, sewer, culvert and or other pipe system 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 drain, sewer, culvert and or other pipe system is buried it is beneficial to internally measure the length of heating cable required with an electrical and 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-DWS 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-DWS system:

  • Factory finished, self-regulating heating cable set installed in ½ inch HDPE polyethylene pipe at a pre-determined length
  • 120V GFC models: 4 ft. (1.2 m) power supply lead with 27 milliamp ground fault circuit interrupter plug-in device
  • 240V GFC models: 6 ft. (1.8 m) power supply lead with 27 milliamp ground fault circuit interrupter plug-in device
  • CS models: 6 ft. (1.8 m), 14 AWG SJEOOW supply cord for direct hardwire connection, GFCI must be field installed
  • 4 inch flexible Fernco pipe coupler
  • 4 inch ABS Nibco threaded male adapter SPIG X MIPT
  • 5 year limited warranty
  • Clear, concise installation and support documentation


Retro-DWS Accessories

DWS-3.00-KITAdapter kit for 3 inch ABS pipe
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-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)
TORQ-60No hub torque wrench automatic release at 60 IN. LB.
WARRANTYExtended 10 year limited warranty


Retro-DWS Product Code Guide

Retro-DWS Product Code Guide

Q – What is the difference between Retro-DWS and Retro-FM?
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-DWS and Retro-Line?
A – Retro-Line is an approved system for internally heat tracing potable water supply pipes and sump pump lines. Retro-DWS is designed for safe and approved installations inside septic pipes and other installations where methane gasses may be present or in large drains where mechanical protection of the heater is desired. The Retro-DWS is engineered strictly for non-pressurized applications where the Retro-Line is cCSAus approved for 75PSI.

Q – What length of Retro-DWS will I need?
A – The length of Retro-DWS 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 further down the pipe.

Q – What do I do if I have extra Retro-DWS heating cable?
A – Care should be given when determining product length required however if the required length is less than what was ordered you can shorten the overall system length by extracting the heating back through the entry grommet. It is recommended to contact Heat-Line to speak with a product specialist for details on this procedure.

Q – Can Retro-DWS be cut if too long?
A – No. The Retro-DWS 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-DWS system is too short; can I add a small section onto the end? If not, what can be done?
A – No. The Retro-DWS 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-DWS system cannot be spliced together or altered in the field. If a greater length of the Retro-DWS 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-DWS system to complete the required freeze protection.

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

Q – Where do I purchase the Retro-DWS heating cable system?
A – The Retro-DWS 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-DWS?
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-DWS 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-DWS consume?
A – All Heat-Line brand systems including Retro-DWS 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-DWS safe for use with plastic pipes?
A – The Retro-DWS system is safe for use with all metallic and non-metallic pipes. The advanced self-regulating technology employed in the Retro-DWS product renders it safe on plastic pipes even when dry as it can never overheat and damage the pipes.

Q – Does the Retro-DWS come with a thermostat?
A – A thermostat is not included with the Retro-DWS 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-DWS system?
A – Insulation is highly recommended when using the Retro-DWS 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-DWS 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-DWS 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-DWS heating cables is fire resistance waterproof pipe foam insulation sleeves.

Q – Does the unit shut off when not required?
A – No. Retro-DWS 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).

Q – If the power fails, do I have to reset the unit?
A – Heat-Line products including Retro-DWS are designed to turn back on as soon as the power to the unit is supplied. Once re-energized the Retro-DWS 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-DWS models for?
A – The indication light located on the GFCI device included with all GFC model Retro-DWS 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-DWS Brochure
  • Retro-DWS Catalogue
  • Retro-DWS Manual
  • Cord-Set (CS) vs Ground-Fault (GFC) Power Supply Options
  • Retro-DWS Application Diagram
  • Retro-DWS Other Installs

3 reviews for Retro-DWS ®

  1. Duane

    I emailed and spoke with a rep for assistance in choosing best product for my situation. Rep was very friendly and helpful! I ordered two Heat Line products for my septic tank. The products arrived in a timely manner and look to be high quality. I will not be able to install until later in the spring.

  2. Scott

    If you’ve got frozen pipes or are worried about them freezing. This is the company you need to contact.

  3. Miles

    We don’t hesitate; we recommend and install Heat-Line products in many situations for sewage lines, well lines and lake systems.
    Our customers are so happy with the Heat-Line products.

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