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ProMelt PM-824 Snow Sensor

SKU# 300824


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The PM-824 is identical to the PM-224 model EXCEPT, The PM-824 has a remote (wired) moisture sensor, not a sensor fixed to the top like the 224.

The Sensor’s 10’ Ft cable allows mounting the control even in a hard to reach location. It can be mounted on a wall or to a rigid conduit or pole. And, the 10 Ft cable can be extended – see instructions for extending.

A weatherproof LED indicator on the base of the 824 provides a method of checking power and trigger status when the unit is mounted in a 'hard to reach' location. Steady OFF indicates no power to the unit. Steady ON indicates power is being supplied but no snow or rain trigger is active. A blinking LED indicates the PM-824 is triggered and connected equipment has been activated.

The PM-824 sensor detects the combination of precipitation PLUS low temperature to activate a Contractor Pro control panel which in turns provides power to ProMelt Mats or Cables. It is meant to be pole-mounted open to the sky and elements and has a heated moisture sensor mounted on its top.

This Low voltage control cannot operate alone – it must be connected to and powered by a contactor control panel. For standalone operation, choose the PM-2B or PM-5 sensor-controllers.

PM-824 provides integrated air and moisture detection within a rainproof and ice-resistant enclosure. The remote wired snow sensor is heated to allow for snow, ice, or freezing rain to melt, allowing proper detection of environmental conditions.

  • 3 operating modes : On-Automatic, On-Manual, Off-standby-reset
  • Low voltage operation (22-28 VAC) and is powered by the CP series panels
  • Connection to a ProMelt CP panel allows control of 250 – 1250 Sq Ft of snow melting, or more.
  • Automatic Activation means lower costs for deicing and snow melting
  • Reliable Rain and Snow Detection
  • Easy Installation with many user configurable options
  • Adjustable temperature and delay settings PLUS exclusive sensitivity control adjustment
  • Removable cover (4 screws) provides full access to all electronics and settings
  • 1 year warranty with many replaceable components and fuse
  • Housed in a sturdy NEMA 3R enclosure rated for outdoor use that is 5"x7"x3"
  • All internal electronic components are specified for -40°C to +85°C operation.

The ProMelt PM-824 offers automatic activation, rain/snow detection, adjustable trigger temperature, and a drying cycle, as well as manual operation. It must be connected to our Contractor Pro series of contactor panels.

We recommend adding the optional PM-DP remote ProMelt Display Panel for the easiest monitoring and control of your PM-824 sensor. The PM-DP wired remote is a great upgrade and is sold separately.



Manufacturer Watts Radiant
Instructions + Video

Instructions + Video

Instruction Manual
Install Steps
  • The PM-824 must be mounted outdoors on top of a piece of rigid conduit secured to a pole or to a free-standing conduit or by using the mounting holes in each corner of the enclosure. Do not install the sensor close to the ground, or any other location, that can cause the sensor to be buried in snow. Mount the PM-824 outdoors, away from furnace vents, dryer vents, and other sources of heat. Do not drill holes in the enclosure.
  • The PM-824 must be installed in a location that exposes the moisture grid to a clear view of the sky and any precipitation. The unit should not be mounted directly under eaves, overhangs, or other obstructions that can block precipitation from reaching the moisture grid.
  • Wire the controller in accordance to the provided schematics. The PM-824 control requires the use of a Contactor Pro Relay Panel to deliver power to the ProMelt system. Refer to the Contactor Pro Relay Panel installation manual for further details.
  • A shielded, outdoor rated 18-24AWG, 4-conductor cable is required to connect the Contactor Pro Relay Panel to the sensor. The total length of this shielded supply wire cable should not exceed 100 feet (30.5 m) for 22 or 24 AWG and 200 feet (61 m) for 18 or 20 AWG. All connections must be made in an outdoor rated, water-tight electrical enclosure.

DO NOT set the Rain switch to 'ON'. Possible overheating of the snowmelt cables may result.

Location / Use : Indoor Only Outdoor Only
More Details

More Details

Why Helps

Automatically controlling your system means lower costs for deicing and snow melting.

Fully automated devices are your best option. The efficient snow sensor system will only activate the radiant heated driveway walkway or other snowmelt area when needed, saving energy and operation costs. This automation detects moisture in the air coupled with low temperatures and turns the system on just as a snow storm arrives for maximum performance and lowest operating costs.

Our sophisticated controls automatically activate the ProMelt snow melt system when it detects precipitation AND temperatures are below 34 F (adjustable). The sensor has several other features, including adjustable temperature trigger point, adjustable delay off cycle, and upgradeable remote activation using the PM-DP.

Snow Melting systems operate best when they are connected to automatic controls.

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