The DS-824 Low Voltage Rain/Snow Sensor Controller

The DS-824 is an advanced low voltage version of the DS-8. It is primarily designed for hydronic and low voltage gutter, downspout, and roof ice melting applications. It can also be used on existing buildings where retrofitting high voltage wiring would be to difficult. The 24VAC/VDC supply means less expensive wiring, no requirement for conduit, and lower installation costs.

The unit is housed in a two gang PVC enclosure. The overall dimensions of the DS-824 are 4¾"(120) x 7"(178) x 2¾"(70). The unit weighs 2 pounds. The user may access all electronics by removing the four front cover screws. The remote precipitation sensor includes 10 feet (3 m) of interconnect cable. A weatherproof LED indicator on the base of the unit provides a method of checking power and trigger status when the unit is mounted in a "hard to reach" location. Steady OFF indi

cates 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 DS-824 is triggered and connected equipment has been activated.

Wiring is performed by terminating your existing wiring to the pre-installed pigtails. The DS-824 is mounted by either attaching the mounting hub to a rigid ½" or ¾" conduit or by installing screws through the four mounting tabs provided.

The DS-824 can be powered from a 22-28VAC/VDC source. Peak power consumption is 15 VA at startup, 8.5 VA steady state triggered, 5 VA steady state untriggered. Power input is polarity protected for a DC supply. The unit provides a single 24VAC/30A or 24VDC/20A normally open load contact set. This contact set is paralleled with a low power contact set to provide remote control and activation monitoring. Operational temperature range is -40^oC to +85^oC.

The table below outlines the operating modes for the DS-824. Trigger Temperature (TT) is adjustable from 34^oF-44^oF using an on-board control. When ambient air temperature (AT) is below this trigger point precipitation is assumed to be snow or freezing rain. When above the trigger point, precipitation is assumed to be rain.

"Delay Off" refers to the internal drying cycle timer of the DS-824. The timer is used to allow the DS-824 to dry the heated surface through evaporation once precipitation has stopped. The drying cycle reduces the chance that moisture left behind by the melting process will refreeze into ice. This timer is restarted by each precipitation detection. Therefore, the DS-824 will continue to operate as long as precipitation and trigger temperature is detected, then for the "Delay Off" time once rain or snow stops. It is assumed that, when operating as a sensor, the DS-824 is supplying an activation signal to an external control system. All "sensor" modes provide a minimum 2 minute closure, reducing cycling of the external controller. The Delay Off cycle has been extended for hydronic applications and is determined by the Long Delay (LD) switch setting, DEL switch setting and the DEL adjustment. Delay Off is 30-90 minutes in non-LD "controller" mode and 2-6 hours in LD "controller" mode.

An environmentally sealed control switch is provided. The "Manual On" function activates the controlled equipment for testing and special operational conditions. The "Automatic" position allows the DS-824 to handle all detections and control. The "Standby/Reset" position disables triggering and can also be used to clear the delay off timer (see below) from true or test activation. If the switch is placed in "Manual On" for less than 2 seconds, then switched back to "Automatic" the controller will execute one delay off cycle. This allows a controlled manual activation of the snow melt system without the fear of forgetting and leaving the system in "Manual On" for an extended and potentially very expensive period of time. "Standby/Reset" can still be used to clear this delay off cycle. Remote control and monitor up to 1000 feet away is also available when the optional CS-1 C/M cable listed is installed. The DS-824 is also compatible with the DP-7B, DP-7EX, and CDP-2 remote control/status panels.

The Low Temperature Cutoff (LTC) option is typically used on deicing or snow melting systems with limited output capacity. If selected, the sensor will not trigger if precipitation is detected below 15^oF. However, if the deicing system has been activated, precipitation continues, and the ambient temperature drops below 15^oF, LTC will be ignored. This assures that water left behind on the surface during the heating cycle will not immediately refreeze into ice as a result of deactivating the deicing system.

The DS-824 also features a new innovation, a Trigger Sensitivity Adjustment. Previous units have always detected and triggered on the first drop of rain, the first flake of snow. While this has always provided a highly reliable detection it may create "nuisance" triggers in some installations. Snow blowing off a roof or falling from a tree could cause the system to activate for a delay cycle when its not needed, increasing operating costs. The sensitivity adjustment allows setting the number of seconds the precipitation grid must see continuous rain or snow before the sensor is triggered and ranges from 3 seconds to 4 minutes. A higher sensitivity setting assures quick detection no matter the conditions. A lower sensitivity setting will allow a few stray drips of rain or flakes of snow to be ignored but a heavier downfall will trigger the system.

Function	Ambient Temp (AT)	Delay Off (LD Off)	Delay Off (LD On)	Suggested Application
Snow sensor w\o LTC	AT < TT	2 Min	2 Min	Snow and ice alert, Sensor for external deice/snow melt controller (unlimited heat)
Snow sensor w\LTC	TT>AT>15^oF	2 Min	2 Min	Sensor for external deice/snow melt controller (limited heat)
Snow controller w\o LTC	AT < TT	30-90 Min	2-6 Hrs	Stand-alone controller for electric/hydronic snow melting
Snow controller w\LTC	TT>AT>15^oF	30-90 Min	2-6 Hrs	Stand-alone controller for electric/hydronic snow melting
Precipitation sensor	Not Used	2 Min	2 Min	Snow, ice, and rain alert, Ku band rain and snow diversion
Precipitation controller	Not Used	30-90 Min	2-6 Hrs	Snow, ice, and rain alert, Ku band rain and snow diversion
Rain sensor	AT>TT	2 Min	2 Min	Rain alert, Ku band rain diversion, skylight control
Rain controller	AT>TT	30-90 Min	2-6 Hrs	Ku band rain diversion, intake and exhaust fan control

DS-824 Specifications
Dimensions	4¾"(120) x 7"(178) x 2¾"(70)
Weight	2 Lbs. (0.9 Kg)
Operating Temperature	-40^oF to +185^oF (-40^oC to +85^oC)
Enclosure Rating	NEMA 3R
Supply Power	22-28VAC/VDC 15VA maximum, 5VA typical
Trigger Temperature	34^oF-44^oF (1.1^oC-6.6^oC) Field Selectable
Delay Off (Sensor)	2 Minutes
Delay Off (Controller)	30-90 Minutes/2-6 Hours Field Selectable
Load Contact Capacity	30A @ 24 VAC/100,000 operations minimum at full load
Monitor Contact Capacity	24 VDC/VAC 400mA 10W total

DS-824 Sensor Controller Part Numbers
Typical leadtime for a DS-824 is stock to 1 week.

Power and load pigtails are MTW UL 1015 105^oC 600V and are 18" in length from base of conduit hub.
Unlike our other products, the DS-824 is not UL listed. No voltages used with or internal to the unit exceed
24 VAC/VDC, a voltage level considered nonhazardous by Underwriters Laboratories.

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info@goase.com

		Type		Conduit Hub
DS	-	824	-	XXX
				\|
				500 - 1/2" NPT
				750 - 3/4" NPT

Part Number	Description
DS-824-xxx	DS-824 with power and load pigtail set
CS-1	Control/Monitor Cable, 18", #22 AWG, 5 Conductor 300V

Part Number	Description
MG-3	Replacement Precipitation Sensor w\10' Cable
RP-1	Thermal Probe Assembly
RP-23	Fuse Kit, 2A 250Vac 3AG (5)
RP-4	Override Switch w\Boot,Cable
RP-5-824	Front Cover w\Label, Gasket, 4 Cover Screws