Taco SR502-5 Switching Relay Instruction Manual

Tools & Materials Needed: Small straight blade screwdriver,
Phillips screwdriver, screws or hardware for mounting, torpedo
level, electrical connectors, wire strippers, low and live voltage
wiring

Installation:

Hang the panel on a wall with one mounting screw.

Level the panel.
Install the other 3 mounting screws.

Operation & DIP Switch Settings:

General Operation:

When a thermostat calls for heat, the corresponding circulating
pump is energized, and the red light turns on. The boiler end
switch relay and AUX circulator relay(s) are also energized based
on DIP switch settings.

Expansion Connections (Modbus):

To set up expansion connections using Modbus, follow the
instructions provided in the manual regarding DIP switch settings
and wiring connections between master and expansion zone
controls.

FAQ:

Q: How many thermostats can be connected to the SR506-5?

A: The SR506-5 can have up to 6 thermostats connected.

Q: What is the priority zone option on the SR506-5?

A: The priority zone option allows zone 1 to operate and
deactivate zones 2 through 6 during a priority call, which is
useful when using an indirect water heater.

Q: Does the SR506-5 support Outdoor Reset?

A: The SR506-5 supports Outdoor Reset (Weather Compensation)
when an outdoor sensor is connected or with a separately purchased
Plug-In Reset Control.

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Instruction Sheet

102-571

SR502/503/504/506-5 Switching Relay

SUPERSEDES: 10/24/24 Plant ID No. 9300-4099

EFFECTIVE: 12/11/24

OVERVIEW:
The “SR50X-5” refers to a model number where “X” represents the number of control zones. Model number “SR506-5” is used for reference in this document. The SR506-5 is a six zone switching relay that can have up to 6 thermostats connected and will operate up to 6 zone circulators, plus 2 auxiliary outputs (AUX) to control circulators in boiler and primary loops, for example.
The SR506-5 has a priority zone option, allowing zone 1 to operate and deactivate zones 2 through 6 during a priority call; this is ideal when using an indirect water heater.
The SR506-5 includes timing options for Post Purge, Pump Exercise and Priority Protection. The SR506-R-5 also includes an energy saving program that can adjust the temperature of a modulatingcondensing boiler or conventional On/ Off boiler to increase the comfort level and use less fuel, without the need to install an outdoor sensor. It also supports Outdoor Reset (Weather Compensation) when outdoor sensor is connected (or separately purchased Plug-In Reset Control for standard SR506-5 model).

For information on Taco’s Switching Relays (SR) including catalog, instruction sheets, submittal data sheets, and our highly praised Zone Controls Wiring Guide, scan the QR code below or visit www.TacoComfort.com.

TABLE OF CONTENTS 1. Warnings & Safety Information 2. Location & Installation 3. Operation & DIP Switch Settings 4. Wiring Procedure 5. Product & Application Diagrams 6. Reset Control Setup & Wiring

7. Troubleshooting & FAQs 8. Fuse Replacement 9. Specifications 10. Accessories & Replacement Parts 11. Warranty

1. WARNINGS & SAFETY INFORMATION: FCC Regulatory Statements This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) This device may not cause harmful interference. (2) This device must accept any interference received, including interference that may cause undesired operation. This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the Federal Communication Commission (FCC) rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment causes harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by doing one or more of the following measures: · Reorient or relocate the receiving antenna. · Increase the separation between the equipment and receiver. · Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. · Consult the dealer or an experienced radio/TV technician for help. NOTE: THE GRANTEE IS NOT RESPONSIBLE FOR ANY CHANGES OR MODIFICATIONS NOT EXPRESSLY APPROVED BY THE PARTY RESPONSIBLE FOR COMPLIANCE. SUCH MODIFICATIONS COULD VOID THE USER’S AUTHORITY TO OPERATE THE EQUIPMENT. RF Exposure Warning This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. In order to avoid the possibility of exceeding the FCC radio frequency exposure limits, human proximity to the antenna shall not be less than 20 cm during normal operation and must not be co-located or operating in conjunction with any other antenna or transmitter. ISED Regulatory Statements This device complies with ISED Canada license-exempt RSS standard(s). Operation is subject to the following two conditions: (1) this device may not cause interference, and (2) this device must accept any interference, including interference that may cause undesired operation of the device. Le présent appareil est conforme avec ISED Canada applicables aux appareils radio exempts de licence. L’exploitation est autorisée aux deux conditions suivantes: (1) l’appareil ne doit pas produire de brouillage, et (2) l’utilisateur de l’appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est susceptible d’en compromettre le fonctionnement. CAN ICES-3 (B)/NMB-3(B) RF Exposure Information This equipment complies with ISED RSS-102 radiation exposure limits set forth for an uncontrolled environment. This transmitter must be installed to provide a separation distance of at least 20 cm from all persons and must not be co-located or operating in conjunction with any other antenna or transmitter. Cet équipement est conforme avec ISED RSS-102 des limites d’exposition aux rayonnements définies pour un environnement non contrôlé. Cet émetteur doit être installé à au moins 20 cm de toute personne et ne doit pas être colocalisé ou fonctionner en association avec une autre antenne ou émetteur.
WARNING: Wiring connections must be made in accordance with all applicable electrical codes. Use copper wire only. 120 VAC wiring must have a minimum temperature rating of 90°C. Failure to follow these instructions can result in personal injury or death and/or property damage. 12-18 gauge wire recommended for 120 VAC connections, 14-22 gauge wire for thermostat connections, and 14-22 gauge wire for 24 VAC source connections. All 24 VAC field wiring terminations require SELV/Class 2 rated wire.
WARNING: Spare fuses consist of different amp ratings (1) 1AMP and (1) 6AMP. Be sure to replace a blown fuse with the correct fuse rating.
2

2. LOCATION & INSTALLATION: Planning:
Included in Package: SR506-5 switching relay; 6 zone 2 Spare fuses attached to inner cover

Quick Start Guide SR506-R-5 switching relay also includes: Strap-on temperature sensor

Tools & Materials Needed: Small straight blade screwdriver

Screws or hardware for mounting

Phillips screwdriver Torpedo level

Electrical connectors for field wiring Low and live voltage wiring (per code)

Wire strippers

Location: Do not mount to a surface that exceeds 104°F (40°C). For indoor use only. The unit must be located in dry interior locations. Use only copper conductor supply wire suitable for at least 90°C. All circuits must have a common disconnect and be connected to the same pole of the disconnect. Product is not suitable for installation in hazardous locations.

Installation:

1. Hang the panel on a wall with one mounting screw.

2. Level the panel.

3. Install other 3 mounting screws.

3. OPERATION & DIP SWITCH SETTINGS:
General Operation: When any thermostat calls for heat, the appropriate circulating pump is energized, the red light goes on and the boiler end switch relay and AUX circulator relay(s) are energized (subject to DIP switch settings).
Expansion Connections (Modbus): Set DIP switch (#1) to MASTER on the switching relay that is designated as the priority zone control. Set all other daisy chained zone controls to EXPANSION. Using thermostat wire (18-22 gauge) connect between terminals A, B, GND on the master control to the corresponding A, B, GND on the expansion zone control(s). Zone controls may be daisy chained up to 20 Taco zoning panels using any combination of SR and ZVC controls (120 zones if all are 6 zone panels).
Modbus is an open protocol method used for transmitting information back and forth over serial lines between Zone Control equipment. This will allow for future expansion to the zone control portfolio and with other participating OEM’s equipment.
Priority Operation: When the priority DIP switch (#2) is set to ON and the priority zone (zone 1) is actuated, all other zones will stop operation until priority zone is satisfied. When not switched to priority, all zones will operate independently. More adjustments are available when using the Taco Control mobile app.
Priority Protection Operation: If the priority zone calls continuously for more than one hour, power is returned to all the other zones, allowing each zone to function independently. Once the priority zone is satisfied, the control’s auto-reset is activated, and the priority zone is again allowed to have priority for up to one hour starting from when it calls next.
Primary Pump Operation: When the DIP switch (#3) is set to OFF, the primary circulating pump output will energize when any zone calls for heat, except the priority zone. When the DIP switch is set to ON, the primary circulating pump output will energize when any zone calls for heat.
Post Purge Operation: When the DIP switch (#4) is set to ON, the last zone on will stay energized for 2 minutes after its thermostat or aquastat is satisfied, but not operate the boiler. More adjustments are available when using the Taco Control mobile app. Note: Post purge is only supported on controls designated as MASTER. Post purge is not supported on expansion controls.
Pump Exercise Operation: When the DIP switch (#5) is set to ON, the solid state timer cycles all the circulating pumps that are attached to the Switching Relay to run for 30 seconds every 2 weeks. More adjustments are available when using the Taco Control mobile app. When using multiple Switching Relays, only the master control DIP switch (#5) should be set to on.
Low Limit (ZC) Operation: When the DIP switch (#6) is set to ON and the boiler drops below the set low limit (terminal ZC connected to boiler), all zone circulating pumps will stop. When the boiler rises above the set low limit, the zone circulating pumps are allowed to operate.
AUX PUMP 1; ZR / DHW Recirc Output: The AUX PUMP 1 output is energized when any zone calls for heat. When a DHW supply sensor is connected to Sensor Input terminals, then AUX PUMP 1 will energize a DHW recirculation pump using SmartPlus® logic. More adjustments are available when using the Taco Control mobile app.
AUX PUMP 2; Primary Circulator Output: The AUX PUMP 2 output follows DIP switch setting #3 listed above. More adjustments are available when using the Taco Control mobile app.
SmartPlus Recirc Logic: SmartPlus adds intelligence to your system by learning when hot water is used in the home. The pipe-mounted sensor records daily hot water usage patterns during the course of the week. Recorded data is used to automatically run the circulator at the same times the following week. So hot water is always available when it is needed. If usage pattern changes, the SmartPlus adjusts automatically.
“Smart” Mode (default mode): The SmartPlus logic will run in Pulse mode as described below for the first 7 days of operation. During the first 7 days, the SmartPlus logic monitors and records the home’s hot water usage pattern. For the following 7 days, the SmartPlus logic will use the preceding week’s usage pattern to cycle the pump during the recorded hot water usage times. This process of recording and repeating is continuous, and automatically adjusts the pump’s “ON” times to match the household’s usage pattern.
“Pulse” Mode: When set to Pulse mode, the SmartPlus logic will cycle the circulator pump “ON” for 5 minutes, then “OFF” for 10 minutes to maintain hot water at all faucets and taps. It will repeat the cycle continuously. More adjustments are available when using the Taco Control mobile app.
When a DHW supply sensor is connected to the Sensor Input terminals, AUX PUMP 1 output will now be designated for recirculation of DHW loop and activated in “Smart” mode based on DHW usage.
4

4. WIRING PROCEDURE: End Switches (Low Voltage Dry Contacts): Main – The main end switch closes when any zone thermostat calls for heat and connects to T-T on boiler operating control. Priority – The priority end switch closes only when the priority zone thermostat or aquastat is calling for heat and connects to DHW T-T on boiler (optional). Thermostat Input (24 VAC):
R Hot side of transformer. Connect to R on thermostat. W Switched R signal from thermostat. Connect to W on thermostat. C Common side of transformer. Connect to COM on thermostat (optional). Note: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Expansion Connections (24 VAC): A Connect A on Master zone control to A on all Expansion zone control(s). B Connect B on Master zone control to B on all Expansion zone control(s). G Connect GND on Master zone control to GND on all Expansion zone control(s). 24V Future use; no connection required. Power Input (120 VAC): H Connect to 120 VAC Hot side of power supply to zone control. N Connect to 120 VAC Neutral side of power supply to zone control. G Connect ground wire to ground screws on base of zone control.
Low Limit Aquastat / Tankless Coil Application (120 VAC): ZR – H Connect the Hot (AUX PUMP 1) output to ZR input on boiler’s operating control. ZR – N Neutral (optional). ZC – H Connect the ZC (Hot) input to ZC (Hot) output on boiler’s operating control. ZC – N Connect (optional). AUX PUMP 1; ZR /DHW Recirc Output (120 VAC):
H Connect the Hot output to Hot power input on circulator. N Connect the Neutral output to Neutral power input on circulator. G Connect ground wire to ground screws on base of zone control. AUX PUMP 2; Primary Circulator Output (120 VAC): H Connect the Hot output to Hot power input on circulator. N Connect the Neutral output to Neutral power input on circulator. G Connect ground wire to ground screws on base of zone control.
5

DHW Recirculation using SmartPlus Logic
SmartPlus Recirc Logic Sensor
· Mount the strap-on sensor on domestic hot water supply pipe on water heater using wire tie or pipe clamp and insulate sensor with pipe insulation.
· The sensor must be strapped to metal piping. A short piece of copper or brass tube should be added into non metallic systems for sensor attachment. For best performance, the strap on sensor should be installed a minimum of 6 feet away from the DHW output but before the first fixture.
· Connect the strap-on sensor to the two terminals labeled Sensor Input Terminal on switching relay.
SmartPlus Recirc Pump Power
· Wire Hot and Neutral from Recirc Pump to Hot and Neutral of AUX PUMP 1 output. Dedicated Return Line Piping Diagram

Dedicated Return Line

Kitchen

Cold Water out to
Fixtures

Laundry Lav
Tub Shower Lav

Temp

Sensor

T G

Switching Relay with SmartPlus Logic

DIP SWITCH SETTINGS

ASSE 1070 / 1017 Dual
Listed Mixing Valve
NSF 61 w/ Integral checks & Temp Gauge
12″ Thermal Trap
Recommended

Water Heater

Check Valve

Potable Exp. Tank
(valve if permitted by local code)

Pressure

Gauge

Isolation Valve P G

P.R.V.

Isolation Strainer Valve

Hose Bibb

Union B.F.P. Union

Incoming Cold Water

Dedicated Return Line

Isolation Valves, Unions and Hose Bibbs as depicted

Hot-Link® Valve or Crossover Style Valve Piping Diagram

Hot-Link bypass valve w/ check
Farthest Sink/Lav away on this particular branch system,
multiple valves may be required

Kitchen Laundry

Cold Water out to
Fixtures

Lav Tub Shower
Temp Sensor
Switching Relay with SmartPlus Logic
DIP SWITCH SETTINGS

T G

ASSE 1070 / 1017 Dual
Listed Mixing Valve
NSF 61 w/ Integral checks & Temp Gauge
12″ Thermal Trap
Recommended

Water Heater

Check Valve

Potable Exp. Tank
(valve if permitted by local code)

Pressure

Gauge

Isolation Valve P G

P.R.V.

Isolation Strainer Valve

Hose Bibb

Union B.F.P. Union

Incoming Cold Water

6 Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

5. PRODUCT & APPLICATIONS DIAGRAMS: PA01C SR506-5 with 5 Zone Circulators & Indirect DHW; Supply & Return Headers Mechanical Diagram
C-ZV
P G
Electrical Diagram
HEAT See
Note 1

See Note 2

DIP Switch Settings 1. OFF – Master 2. ON – Priority 3. OFF – Primary Pump 4. OFF or ON – Post Purge 5. OFF or ON – Pump Exercise 6. OFF ZC Low Limit

Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

PA02C – SR506-5 with 5 Zone Circulators & Indirect DHW; Primary/Secondary Mechanical Diagram
See Note 3

Electrical Diagram
Z
,
d d
WtZ
E ,

^ EZ
See Note 1

KhdWhd

K/>Z KhdKKZ ^E^KZ ^E^KZ

KZ/KZZ /ZZKZZZ

Z
^
d &
&Z
^ ^
>Z t Z
See No^te2 EZ

See Note 3

DIP Switch Settings 1. OFF – Master 2. ON – Priority 3. OFF – Primary Pump 4. OFF or ON – Post Purge 5. OFF or ON – Pump Exercise 6. OFF ZC Low Limit

Note 1: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Note 2: Ensure load of zone control, circulator(s) & boiler do not exceed LWCO rating. Note 3: Follow boiler manufacturer’s recommendations on powering of boiler loop circulator. Some boilers require this circulator to be wired to the boiler operating control.
8 Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

PA03C High & Low Temperature Zones & Indirect DHW; Primary/Secondary Electrical Diagram
9

Outdoor Sensor
Supply Sensor
BOL SUP OUT COM C R

DIP Switch Settings – Master 1. OFF – Master 2. ON – Priority 3. OFF – Primary Pump 4. OFF or ON – Post Purge 5. OFF or ON – Pump Exercise 6. OFF ZC Low Limit
DIP SWITCH SETTINGS

DIP Switch Settings – Expansion 1. ON – Expansion 2. OFF – Priority 3. OFF – Primary Pump 4. OFF or ON – Post Purge 5. OFF or ON – Pump Exercise 6. OFF ZC Low Limit

DIP SWITCH SETTINGS

SR Switching Relay 4 ZONE
SR504-5

Power Zone 1 Priority Zone 2 Zone 3 Zone 4
Main Boiler Priority Boiler
Aux 1 Aux 2

Note 1: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Note 2: Ensure load of zone control, circulator(s) & boiler do not exceed LWCO rating. Note 3: Follow boiler manufacturer’s recommendations on powering of boiler loop circulator. Some boilers require this circulator to be wired to the boiler operating control.
Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

PA04C Boiler with Tankless Coil; Supply & Return Headers Mechanical Diagram

Electrical Diagram

P G
LEGEND

DIP SWITCH SETTINGS

DIP Switch Settings 1. OFF – Master 2. OFF – Priority 3. OFF – Primary Pump 4. OFF or ON – Post Purge 5. OFF or ON – Pump Exercise 6. ON ZC Low Limit

SAFETY NOTICE – TWO SEPARATE sources of power may be connected to an oil boiler’s aquastat control. Before servicing an oil fired boiler, make sure the service switch is off. Then confirm that a secondary source of power does not exist to the boiler’s aquastat control. Failure to fix the problem could result in boiler being activated when zone calls for heat, that could result in serious injury or death. Note 1: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Note 2: Ensure load of zone control, circulator(s) & boiler do not exceed LWCO rating.
10 Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

PA05C Legacy Zone Controls SR506-EXP-4 (Master) Connected to SR504-5 (Expansion) Electrical Diagram
11

MAIN A PRIORITY B C R W C R W C R W C R W C R W C R W C

BOILER END

EXPANSION T STAT 1 T STAT 2 T STAT 3 T STAT 4 T STAT 5 T STAT 6

SWITCH SWITCH

(PRIORITY)

Power Controls

DIP SWITCH

SR506-4
6 ZONE SWITCHING
RELAY

Power
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6

120 VAC

(PRIORITY) N/C 12012V0AC PRIMARY ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6 ZONE 6 POVWAERC IN

ZC ZR N H N H N H N H N H N H N H N H N H

DIP SWITCH SETTINGS

SR Switching Relay 4 ZONE
SR504-5

Power Zone 1 Priority Zone 2 Zone 3 Zone 4
Main Boiler Priority Boiler
Aux 1 Aux 2

Note 1: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Note 2: Ensure load of zone control, circulator(s) & boiler do not exceed LWCO rating. Note 3: Follow boiler manufacturer’s recommendations on powering of boiler loop circulator. Some boilers require this circulator to be wired to the boiler operating control. Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

PA06C Legacy Zone Controls SR504-5 (Master) Connected to SR506-EXP-4 (Expansion) Electrical Diagram
12

SR Switching Relay 4 ZONE
SR504-5

DIP SWITCH SETTINGS
Power Zone 1 Priority Zone 2 Zone 3 Zone 4
Main Boiler Priority Boiler
Aux 1 Aux 2

MAIN A PRIORITY B C R W C R W C R W C R W C R W C R W C

BOILER END

EXPANSION T STAT 1 T STAT 2 T STAT 3 T STAT 4 T STAT 5 T STAT 6

SWITCH SWITCH

(PRIORITY)

Power Controls

DIP SWITCH

SSSRRR555000666—444
66ZZOONNEE SSWWIITTCCHHIINNGG
RREELLAAYY

PPoowweerr
ZZoonnee11 ZZoonnee22 ZZoonnee33 ZZoonnee44 ZZoonnee55 ZZoonnee66

112200 VVAACC

(PRIORITY) N/C 12012V0AC PRIMARY ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6 ZONE 6 POVWAERC IN

ZC ZR N H N H N H N H N H N H N H N H N H

‘

Note 1: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Note 2: Ensure load of zone control, circulator(s) & boiler do not exceed LWCO rating. Note 3: Follow boiler manufacturer’s recommendations on powering of boiler loop circulator. Some boilers require this circulator to be wired to the boiler operating control. Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

PA07C Legacy Zone Controls SR504-5 (Master) Connected to SR506-EXP-2 (Expansion) Electrical Diagram
13

DIP SWITCH SETTINGS

Expansion
1234 EXPANSION

RWCRWCRWC RWC RWCRWC T STAT 1 T STAT 2 T STAT 3 T STAT 4 T STAT 5 T STAT 6
(PRIORITY)
SR506-2
6 ZONE SWITCHING RELAY

Power
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6

X X 120

(PRIORITY) 120 VAC

End

VAC ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6 POWER IN

Switch ZC ZR N H N H N H N H N H N H N H

‘
Note 1: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Note 2: Ensure load of zone control, circulator(s) & boiler do not exceed LWCO rating. Note 3: Follow boiler manufacturer’s recommendations on powering of boiler loop circulator. Some boilers require this circulator to be wired to the boiler operating control. Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

PA07C Legacy Zone Controls SR506-EXP-4 (Master) with PC700-2 Boiler Reset Control Connected to SR504-5 (Expansion) Electrical Diagram
14

No Npoower
1po2wer3
Boi Ou Co l tm

MAIN A PRIORITY B C R W C R W C R W C R W C R W C R W C

BOILER END

EXPANSION T STAT 1 T STAT 2 T STAT 3 T STAT 4 T STAT 5 T STAT 6

SWITCH SWITCH

(PRIORITY)

Power Controls

DIP SWITCH

SR506-4
6 ZONE SWITCHING
RELAY

Power
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6

120 VAC

(PRIORITY) N/C

120

PRIMARY ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6 ZONE 6 POVWAECR IN

ZC ZR N H N H N H N H N H N H N H N H N H

DIP SWITCH SETTINGS

SR Switching Relay 4 ZONE
SR504-5

Power Zone 1 Priority Zone 2 Zone 3 Zone 4
Main Boiler Priority Boiler
Aux 1 Aux 2

Note 1: Some “Power Stealing” style thermostats may require a resistor between the W & C terminals; a 1000 Ohms 1/2 watt (or larger) have proved to work. Note 2: Ensure load of zone control, circulator(s) & boiler do not exceed LWCO rating. Conceptual Sketches Only, refer to individual manufacturer’s installation instructions for additional details. Local codes shall prevail.

6. RESET CONTROL SETUP & WIRING (OPTIONAL)
Boiler Reset Types: The SR506-R-5 includes two types of boiler reset control logic: (or separately purchased Plug-In Reset Control for standard SR506-5 model)
Indoor Reset Control (Load Reset) uses the thermostat cycling information to determine the supply water temperature. Thermostat short cycling often suggests that the supply water temperature is too high, while prolonged cycles typically indicate that the water temperature is too low.
Outdoor Reset Control (Weather Compensation) uses an outdoor sensor to compare it against the reset ratio (configured by installer) to determine the appropriate supply water temperature. Outdoor sensor must be purchased separtately.
General Operation: When any thermostat calls for heat, the appropriate circulator is energized, and the red light goes on. The boiler end switch relay and modulating output will be controlled by the reset algorithm; or, either based on indoor thermostat operation or on outdoor temperature.
Control Setup: The Taco Control mobile app is required to set type of reset control and parameters to operate.

Wiring of Reset Control: Make all sensor and analog output connections to the small Plug-In Reset Control on SR506-R-5.

Sensor Connections: Boiler Sensor:

A boiler supply sensor is required for either indoor or outdoor reset. Mount the provided strap-on sensor to the supply piping of the boiler, and wire it to the Boiler Sensor terminal block on the zone control.

Outdoor Sensor:

An outdoor sensor is required when utilizing the outdoor reset function. Mount the Taco outdoor sensor P# 9300-2052RP on north side of building and wire to Outdoor Sensor terminal block on zone control.

Boiler Connections: Modulating Output:

Most Mod-Con boilers have an input for an external modulating signal (0-10 vdc or 4-20 ma) to control boiler. Connect the modulating output to appropriate input terminals on boiler; noting that the polarity is correct. Some Mod-Con boilers also require a T T call for heat to activate boiler. In this case, wire the Main Boiler End Switch to T T input on boiler.

Dry Contact End Switch: ON/OFF boilers are controlled by the Main Boiler End Switch on zone control. Wire the Main Boiler End Switch to T T input on boiler.

7. TROUBLE SHOOTING & FAQs

Problem: Digital thermostats do not work correctly when connected to a switching relay. Solution: Some thermostats are a “Power Stealing” type which means they are powered by the switching relay with just 2 wires (R & W). A resistor may be needed in order to have the thermostat work properly. This resistor should be placed between the W & C (common) terminals of the switching relay. If the thermostat manufacturer does not supply a resistor, a 1000 ohm ½ watt resistor has proven to work with most.

Problem: No heat in a zone or room of building. Solution: LED diagnostic lights will help find a component that is not working properly. The green LED should always be on, indicating that power is connected, and the solid-state fuse is good. When there is a call for heat, the red LED will come on indicating power to the zone circulator. This indicates the thermostat is working correctly. If the red LED does not come on, then check the thermostat and thermostat wiring for errors.

Trouble Shooting Sensors:

As in any troubleshooting procedure, it is important to isolate a problem as much as possible before proceeding. The blinking error LED light greatly simplifies troubleshooting of the SR50X-R-5. If you suspect a wiring fault, return to section 4 and carefully check all external wiring and wiring connections.

Sensor Errors:

· If an outdoor sensor fault occurs, the SR50X-R-5 will assume a fixed outdoor temperature of 32°F (0°C) and will target the appropriate supply water temperature. The Main Boiler light will blink indicating the outdoor sensor error.

· If a boiler sensor fault occurs, the SR50X-R-5 turns the boiler output off and the Priority Boiler light will blink indicating the boiler supply sensor error.

Testing the Sensors:

Sensor Boiler Sensor Outdoor Sensor Universal Sensor (Recirc)

Sensor Error Handling Shorted Sensor
Flash once Main Boiler LED Flash once Priority Boiler LED Flash once AUX PUMP 1 LED

Open Sensor Flash twice Main Boiler LED Flash twice Priority Boiler LED Flash twice AUX PUMP 1 LED

A good quality test meter capable of measuring up to 5,000 k (1 k = 1000 ) is required to measure the sensor resistance. In addition to this, the actual temperature must be measured with either a good quality digital thermometer, or, if a thermometer is not available, a second sensor can be placed alongside the one to be tested and the readings compared. First, measure the temperature using the thermometer and then measure the resistance of the sensor at the control. The wires from the sensor must not be connected to the control while the test is performed. Using the chart below, estimate the temperature measured by the sensor. The sensor and thermometer readings should be close. If the test meter reads a very high resistance, there may be a broken wire, a poor wiring connection or a defective sensor. If the resistance is very low, the wiring may be shorted, there may be moisture in the sensor, or the sensor may be defective. To test for a defective sensor, measure the resistance directly at the sensor location.

Temperature ºF ºC -30 -34 -20 -29 -10 -23 0 -18 10 -12 20 -7

Resistance
234,196 165,180 118,018 85,362 62,465 46,218

Temperature

ºF ºC

30 -1

50 10

60 16

70 21

80 27

Resistance
34,558 26,099 19,900 15,311 11,883 9,299

Temperature ºF ºC 90 32 100 38 110 43 120 49 130 54 140 60

Resistance
7,334 5,828 4,665 3,760 3,050 2,490

Temperature ºF ºC 150 66 160 71 170 77 180 82 190 88 200 93

Resistance
2,045 1,689 1,403 1,172 983 829

8. FUSE REPLACEMENT: Fuses are replaceable; 2 spare fuses are attached to inside of front cover.
WARNING: Spare fuses consist of different amp ratings (1) 1AMP and (1) 6AMP. Be sure to replace a blown fuse with the correct fuse rating.

9. SPECIFICATIONS:
Power and Electrical Ratings:
Power Supply: 120 VAC ±10%, 60Hz, 20A
Zone Pump Output Rating: 120 VAC, 1/6 HP
AUX(s) Pump Output Rating: 120 VAC, 1/6 HP
Boiler End Switch Contact Rating: 24 VAC, 1A
Expansion Terminals: Low voltage, 3-wire polarity-sensitive, digital communications that links other Switching Relays (SR-5), Zone Valve Controls (ZVC-5) and other Modbus equipment.
Electrical Terminals (Line Voltage): Wire Range: 1218AWG Torque Screws: 7.0 lbs-in. Max.
Electrical Terminals (Low Voltage): Wire Range: 1422AWG Torque Screws: 3.5 lbs-in. Max.
Transformer Rating: 20 VA, 24 VAC Class II 40 VA with option of second 20 VA transformer
ZC Input Rating: 120 VAC

Environmental Ratings:
Ambient Temperature Rating: 32°F to 104°F (0°C to 40°C)
Operating Humidity Range (% RH): 5 to 90% RH, noncondensing
Sensor Temperature Rating: -58°F to 230°F (-50°C to 110°C)
DIP Switch Timing Settings:
Post Purge: 30 seconds; adjustable with Taco Control mobile app
Pump Exercise: 30 seconds per 2 weeks of space heating inactivity; adjustable with Taco Control mobile app
Thermostat Compatibility: Compatible with most mechanical, battery operated, power-stealing (powerrobbing), hardwired and “Smart” thermostats.
Temperature Sensor: 10K ohm NTC thermistor at 77°F (25°C) ± 0.5°F (±0.3°C), beta=3892. Lead length: up to 500 ft. (150 m) using 18 AWG or larger wire.
Dimensions (HxWxD): 12.58 x 8.44 x 2.66 in. (31.95 x 21.44 x 6.76 cm) approximate
Weight: 4.83 lb. (2.19 kg)
Approvals: UL, FCC
Boiler Modulating Output Rating: 0-10 VDC Mode; 500 min impedance 4-20 mA Mode; 1k max impedance (With Plug-In Reset Control)

10. ACCESSORIES & REPLACEMENT PARTS Item
Strap-on sensor for boiler reset control or SmartPlus logic Outdoor sensor for outdoor boiler reset and smart pump exercise Circulator output fuses; slow blow, 6 amp, 2AG (5mm X 15mm) Slow blow, 1 amp, 2AG (5mm X 15mm) Transformer; 20 VA at 24 VAC with connectors to plug into board Plug-In Reset Control board and strap-on temperature sensor PC700’s adaptor (Allows PC700, PC702 and PC705 to work with new zone controls) Power Stealing thermostat resistor 1000 OHM, 0.5 Watt

Part Number 9300-4168RP 9300-2052RP SR6A-001RP SR1A-001RP 9300-4164RP
PC800-5 9300-4166RP SRTR-001RP

11. WARRANTY
Taco, Inc. will repair or replace without charge (at the company’s option) any product or part which is proven defective under normal use within three (3) years from the date code.
In order to obtain service under this warranty, it is the responsibility of the purchaser to promptly notify the local Taco stocking distributor or Taco in writing and promptly deliver the subject product or part, delivery prepaid, to the stocking distributor. For assistance on warranty returns, the purchaser may either contact the local Taco stocking distributor or Taco. If the subject product or part contains no defect as covered in this warranty, the purchaser will be billed for parts and labor charges in effect at time of factory examination and repair.
Any Taco product or part not installed or operated in conformity with Taco instructions or which has been subject to misuse, misapplication, the addition of petroleum-based fluids or certain chemical additives to the systems, or other abuse, will not be covered by this warranty.
If in doubt as to whether a particular substance is suitable for use with a Taco product or part, or for any application restrictions, consult the applicable Taco instruction sheets or contact Taco at [401-942-8000].
Taco reserves the right to provide replacement products and parts which are substantially similar in design and functionally equivalent to the defective product or part. Taco reserves the right to make changes in details of design, construction, or arrangement of materials of its products without notification.

TACO OFFERS THIS WARRANTY IN LIEU OF ALL OTHER EXPRESS WARRANTIES. ANY WARRANTY IMPLIED BY LAW INCLUDING WARRANTIES OF MERCHANTABILITY OR FITNESS IS IN EFFECT ONLY FOR THE DURATION OF THE EXPRESS WARRANTY SET FORTH IN THE FIRST PARAGRAPH ABOVE.
THE ABOVE WARRANTIES ARE IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR STATUTORY, OR ANY OTHER WARRANTY OBLIGATION ON THE PART OF TACO.
TACO WILL NOT BE LIABLE FOR ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OF ITS PRODUCTS OR ANY INCIDENTAL COSTS OF REMOVING OR REPLACING DEFECTIVE PRODUCTS.
This warranty gives the purchaser specific rights, and the purchaser may have other rights which vary from state to state. Some states do not allow limitations on how long an implied warranty lasts or on the exclusion of incidental or consequential damages, so these limitations or exclusions may not apply to you.

A Taco Family Company
2024
18

Documents / Resources

Taco SR502-5 Switching Relay [pdf] Instruction Manual
SR502-5, SR503-5, SR504-5, SR506-5, SR502-5 Switching Relay, SR502-5, Switching Relay, Relay

References

User Manual

Taco SR502-5 Switching Relay Instruction Manual

SR502-5 Switching Relay

Specifications:

Product Usage Instructions:

Warnings & Safety Information:

Location & Installation:

Operation & DIP Switch Settings:

FAQ:

Q: How many thermostats can be connected to the SR506-5?

Q: What is the priority zone option on the SR506-5?

Q: Does the SR506-5 support Outdoor Reset?

Documents / Resources

References

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