Taco SR501-HC-4 User Manual

ONE ZONE HC

SWITCHING RELAY

SR 501-HC-4

LED

INDICATORS

R

W1

24 VAC

THERMOSTAT

W2

COM

24

VAC

TTT

NHX1

RELAY 2RELAY 1

120 VAC

INPUT

120 VAC

CIRCULATOR

X1

X2

X2

N

ZR

ZC

H

POWER INPUT

(120 VAC)

POWER

RELAY 1

RELAY 2

See NOTE 1

NOTE 1: Resistor
(1KΩ,

1

⁄2 W)
may be needed
between W and C
terminals.

ONE ZONE HC

S

WITCHING RELAY

S

R 501-HC-4

LED

INDICATORS

R

W1

24 VAC

THERMOSTAT

W2

COM

24

VAC

TT T

NHX1

RELAY 2RELAY 1

120 VAC

INPUT

P

OWER

INPUT

(120 VAC)

120 VAC

CIRCULATOR

X1

X2

X2

N

H

BOILER

C

ONTROL

POWER

RELAY 1

RELAY 2

S

ee NOTE 1

102-418

Instruction Sheet

SR501-HC-4 Switching Relay, High Current Capacity

SUPERSEDES: March 1, 2013 EFFECTIVE: December 20, 2013
Plant ID# 9300-2795

Features:

External Indicator Lights

Typical

iring:

W

Simplified Wiring
Sealed Relays
100% Factory Tested
Contractor Friendly PC Board
Layout
Universal Thermostat Compatibility
UL Approved
Extended 3 Year Warranty

120 VAC Application:

1 zone switching relay with boiler
enable or 2 zone without boiler
enable.

240 VAC Application:

1 zone switching relay when switch­ing both of the circulator
hot leads (L1 & L2).

Operation:

Connect a thermostat to the R & W1
and/or W2 terminals on the switching
relay. When the thermostat(s) call for
heat, the relays are energized and
power is given to the circulator(s).

Zone Control Power Input:

Connect 120 volt AC power input to terminals N and H.
Neutral wire to terminal N. Hot wire to terminal H.

External Diagnostics:

The external lights show full functionality of the switching
relay. The green light should always be on, indicating that
power is connected. When either thermostat calls for heat, both
the appropriate relay and red indicating light are energized.

Terminal Description:

R Hot side of transformer. Connect to R on thermostat.
W1 Switched R signal from thermostat #1. Connect to

W on thermostat.

W2 Switched R signal from thermostat #2. Connect to

W on thermostat.

C Common side of transformer. Connect to COM

on thermostat (optional).
N Neutral wire of power input.
H Hot wire of power input.
X1 Dry contacts for relay 1 (W1).
X1 Dry contacts for relay 1 (W1).
X2 Dry contacts for relay 2 (W2).
X2 Dry contacts for relay 2 (W2).

Specifications:

PRODUCT NUMBER INPUT TYPE 1 ENCLOSURE

NUMBER OF ZONES VOLTAGE WIDTH HEIGHT DEPTH

SR501-HC-4 1 or 2 120/60/1 VAC, 90 mA 47/8"65/8"23/8"

RELAY RATING: 3/4HP (13.8 FLA, 82.8 LRA at 120 VAC) (6.9 FLA, 41.4 LRA at 240 VAC)
The thermostat connection supplies a 24 VAC class 2 output.

WARNING: Wiring connections must be made in accordance with all
applicable electrical codes. Use copper wire only. Failure to follow this
instruction can result in personal injury or death and/or property
damage. 12-18 gauge wire recommended for 120/240 VAC connec­tions, 14-22 gauge wire for thermostat connections, and 14-22 gauge
wire for 24 VAC source connections.

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, and (2) this device must accept any
interference received, including interference that may cause undesired operation.

Alternative
Wiring:

NOTE 2: When using Alternative Wiring diagram, the boiler operating

control’s ZC terminal will see the load of the circulator(s).
WARNING: When using Alternative Wiring diagram, wiring instruc-

tions must be followed so power originates from the boiler aquastat.
Failure to follow these wiring instructions may result in a secondary
source of power being connected to the boiler that may activate it
under certain circumstances, causing injury or death.

Troubleshooting:

• 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
models and is readily available at electronic supply outlets (e.g.
Radio Shack). If the thermostat is battery powered, then check
that the batteries are fresh and installed correctly.

• 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.

For information on Taco’s Switching Relays (SR)
including catalog sheet, instruction sheets, Visio
stencils and our highly praised Zone Controls
Wiring Guide, scan the QR code to the right or
go to our website: http://www.taco-hvac.com.

O

NE ZONE HC

SWITCHING RELAY

SR 501-HC-4

L

ED

INDICATORS

R

W1

24 VAC THERMOSTAT

W2

COM

24

VAC

TT T

NHX

1

R

ELAY 2RELAY 1

120 VAC

INPUT

240 VAC

CIRCULATOR

X1

X2

X

2

N

H

1

H2

ONE ZONE, NO BOILER ENABLE

(CONTROL & CIRCULATOR SAME POWER SOURCE)

C

ONTROL POWER

INPUT (120 VAC)

POWER

RELAY 1

RELAY 2

(

240 VAC)

{
{

O

NE ZONE HC

SWITCHING RELAY

SR 501-HC-4

LED

INDICATORS

R

W1

24 VAC THERMOSTAT

W2

COM

24

VAC

TT T

NHX1

R

ELAY 2RELAY 1

1

20 VAC
INPUT

240 VAC

CIRCULATOR

X1

X2

X2

N

H1

H2

ONE ZONE, NO BOILER ENABLE

(CONTROL & CIRCULATOR DIFFERENT POWER SOURCE)

H

POWER

RELAY 1

RELAY 2

CONTROL POWER

INPUT (120 VAC)

(240 VAC)

{

{

ONE ZONE HC

SWITCHING RELAY

S

R 501-HC-4

LED

INDICATORS

R

W1

W2

COM

24

VAC

TT T

NHX1

RELAY 2RELAY 1

120 VAC

INPUT

CIRCULATOR #1

(

120 VAC)

X1

X2

X2

N

TWO ZONE, NO BOILER ENABLE

H

CIRCULATOR #2

(120 VAC)

T

HERMOSTAT #2

(24 VAC)

THERMOSTAT #1

(24 VAC)

POWER

I

NPUT

(120 VAC)

POWER

RELAY 1

RELAY 2

Replacement Switching Relay fuses part number: SR6A-001RP

(Manufacture: Littlefuse, Part Number: 229006)

Optional power stealing thermostat resistor part number: SRTR-001RP

(Value: 1000 Ohms, 1/2 watt or higher)

LIMITED WARRANTY STATEMENT

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 of start-up or
three (3) years and six (6) months from date of
shipment (whichever occurs first).

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

Do it Once. Do it Right.

TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: [phone] FAX: [phone].
TACO (Canada), Ltd., 8450 Lawson Road, Unit #3, Milton, Ontario L9T 0J8. Telephone: [phone]. FAX: [phone].

Visit our web site at: http://www.taco-hvac.com

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 FIT-

®

NESS 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.

Printed in USA

Copyright 2013

TACO, Inc.