IS-PM824
Instructions for Installing PM-824
Remote snow/ice sensor
The PM-824 is a 24 volt, self contained snow and ice detector. Each
PM-824 can be set to operate within a range of 22-28 V. The integrated
snow sensor is heated to allow for snow, ice, or freezing rain to melt,
allowing proper detection of environmental conditions.
Installation
The PM-824 control can be mounted in any location as long as the
moisture grid sensor is installed in a location that exposes the moisture
grid to a clear view of the sky and any precipitation.
Note: the moisture
grid should not be mounted directly under eaves, overhangs, or
other obstructions that can block precipitation from reaching the
moisture grid.
Do not install the control or sensor close to the ground, or any other
location, that can cause the unit to be buried in snow.
Mount the PM-824 moisture grid outdoors, away from furnace vents, dryer
vents, and other sources of heat. The PM-824 control can be mounted to a
free-standing conduit or by using the mounting holes in each corner of the
enclosure. Do not drill holes in the enclosure.
Wire the controller in accordance to the provided schematics.
Operation
Before installing and wiring the PM-824 sensor, it is
important to set all power and control settings prior to
wiring or mounting.
1. Set the Temp Adjust control for desired melting
conditions. Precipitation below this temperature is
assumed to be snow, above rain. Control comes with
the Temp Adjust dial set to 39°F.
2. Set the Delay (DEL) time for 30–90 minutes when the
LD (Long Delay - see #3) switch is set to OFF, or 2 – 6
hours when LD is ON.
The Delay function will allow the snowmelt system to
run for the set time frame after moisture is no longer
detected (once snowfall has stopped). This is to help
prevent "black ice" from forming.
3. Determine how the sensor operates by setting the
toggles located at S1.
Snow:
On – the control will operate when precipitation is detected below
the Temp Adjust setting.
Recommended: ON
Rain:
On – the control will operate when precipitation is detected above
the Temp Adjust setting.
Required: OFF
DEL:
On – the control will operate with a Delay Off time. If this function
is set to Off, the control will operate with a 2 minute delay to
prevent short-cycling of external components.
Recommended: ON
LTC:
On – the control will operate in Low Temperature Cutoff mode,
preventing operation when Ambient Temperatures (AT) fall below
15°F.
Recommended: ON
LD:
On - the control will operate with a Delay (DEL) time (see #2
above) of 2 - 6 hours. If this function is Off, the control will operate
with a 30 - 90 minute Delay time.
Recommend-
ed: OFF
4. The control monitors the moisture sensor once every second for the
presence of moisture. Setting the sensor sensitivity dial to "Less"
requires a full four (4) minutes of detection before the unit activates
the snowmelt system. Set to "More" requires only three (3) seconds
of detection. Adjust this setting to avoid nuisance triggering due to
condensation, blowing snow, or high winds, or flurry conditions.
Power must be cycled for switch changes to take effect.
Manual Override Switch
An override switch is mounted on the side for testing and special
operational requirements. Placing the switch in the "Automatic" position
will allow the sensor to operate normally. "Manual On" will activate the
control and will stay activated for a maximum of 40 hours before returning
to "Automatic" mode. The "Stand-by/Reset" position will clear any current
snowmelt call or delay activity.
If the Manual Override Switch is moved to Manual On for less than
2 seconds and then back to Automatic the sensor will execute one delay
off cycle. This can be used to clear frost, hail, drifting snow, or other
conditions. Stand-by/Reset will clear this setting.
FMO
30M
(2H)
60M
(4H)
90M
(6H)
FMO
30M
(2H)
60M
(4H)
90M
(6H)
FMO
30M
(2H)
60M
(4H)
90M
(6H)
FMO
30M
(2H)
60M
(4H)
90M
(6H)
!
WARNING: General Safety Instructions
1.
THIS UNIT SHOULD BE INSTALLED ONLY BY
QUALIFIED PERSONNEL!
2. Disconnect all power from the control, or any associated equipment,
before opening the front cover plate.
3. Limit input voltage to 22-28 VAC/VDC
4. To avoid fire hazard, replace fuse
only
with 2 Amp 32 V or 250 V 3AG
fast acting fuse.
5. Do not drill holes through the electrical enclosure for mounting.
Mount the control to a free-standing conduit or via the pre-determined
mounting holes.
6. Ensure front cover gasket is properly installed when replacing cover.
�
ENCLOSURE TYPE 3R
PM-824 provides integrated air and moisture detection within a rainproof
and ice-resistant enclosure. The moisture grid can be locate up to 10 ft
away from the main control.
Air Temperature Sensor
Wiring Access
Control Switch
Moisture Grid
