Specification
Job __________________________
Designer ______________________
Contact _______________________
Programmable Thermostat 521
521
_
C
01/14
Zoning
Replaces: New
Submittal
© 2014 521_C - 01/14
1 of 2
A Watts Water Technologies Company
Energy Saving Features
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7 Day Programmable Schedule
Additional Features
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Optimum Start
Permanent Temperature Hold
Radiant Floor Heating
Two Stage Heating
Cooling
Fan
Backlight
Outdoor and Floor Temperature Display
Time Clock
Four Hour Battery-free Clock Backup
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Specifications
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The Programmable Thermostat 521 is designed for three different modes of operation: single stage heating, two stages
of heating with a fan, or one stage of heating and one stage of cooling with a fan. Two auxiliary sensors may be added to
measure the floor, outdoor or room temperature. A Slab Sensor 079 is included to measure floor temperature to protect
the floor from overheating and enhance comfort. The programmable schedule supports either a 7 day or 24 hour schedule
with 2 or 4 events per day. A permanent temperature hold button overrides the programmable schedule. An optional
Adaptor Plate 012 is available to allow the thermostat to mount onto a single gang electrical box.
Programmable Thermostat 521 Two Heat or Heat-Cool (Includes Sensor 079)
Literature 521_A, 521_C, 521_D, 521_Q, 521_U
Control Microprocessor control. This is not a safety (limit) control
Packaged weight 0.6 lb. (290 g)
Dimensions 3-11/16" H x 3" W x 15/16" D (94 x 76 x 24 mm)
Enclosure White PVC plastic, NEMA type 1
Approvals
Meets Class B: ICES & FCC Part 15, CE
Ambient conditions
Indoor use only, 32 to 122°F (0 to 50°C),
RH ≤90% non-condensing
Power supply 10 to 30 V (ac/dc), 50/60 Hz, 1.8 VA, Class 2
Relays 30 V (ac/dc) 2 A, Class 2 circuits
Sensor
NTC thermistor, 10 kΩ @ 77°F (25°C ±0.2°C) ß=3892
–Included
Slab Sensor 079
–Optional
tekmar type # 070, 072, 073, 076, 077, 079, 084
Warranty Limited 3 Year (See 521_D for full warranty)
521 Front View
3–11/16"
(94 mm)
3"
(76 mm)
521 Side View
15/16"
(24 mm)
521 Mounting Base
C R
Y/W2
Rc GGRh W1 S1 S2Com
No Power
9/16"
(15 mm)
2-13/16"
(72 mm)
1–3/16"
(30 mm)
2–3/8"
(60 mm)
3–9/16"
(90 mm)
9/16”
(14 mm)
2-5/16" (60 mm)
2-1/16" (53 mm)
Scan code for quick
link to product page on
tekmarControls.com
Slab Sensor 079
10’ (3 m) wire
Dimensions 3/16” OD x 1-1/2” (5 mm OD x 38 mm)
Enclosure
316 stainless steel, 10’ (3 m) 24 AWG, 300 volt PVC insulated Zipcord
Approvals CSA C US
Operating range -58 to 221°F (-50 to 105°C)
Sensor NTC thermistor, 10 kΩ @ 77°F (25°C ±0.2°C) ß=3892
Slab Sensor 079
3/16”
(5 mm)
Supplied with:
10’ (3 m)
2-conductor wire
1–1/2”
(38 mm)