Install Instructions

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 prod-
uct or part, delivery prepaid, to the stocking dis-
tributor. For assistance on warranty returns, the
purchaser may either contact the local Taco
stocking distributor or Taco. If the subject prod-
uct 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 operat-
ed 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 sim-
ilar in design and functionally equivalent to the
defective product or part. Taco reserves the
right to make changes in details of design, con-
struction, 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 SPE-
CIAL, INCIDENTAL, INDIRECT OR CONSE-
QUENTIAL 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.
LIMITED WARRANTY STATEMENT
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
Printed in USA
Copyright 2012
TACO, Inc.
ond sensor can be placed alongside the one to be tested and the read-
ings 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.
The installer must ensure that this control and its wiring are isolated
and/or shielded from strong sources of electromagnetic noise.
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 inter-
ference, and (2) this device must accept any interference received,
including interference that may cause undesired operation.
TECHNICAL DATA:
SR501-OR Boiler Reset Control Relay:
Control: Microprocessor PI control. This is not a
safety (limit) control.
Enclosure: TYPE 1
Dimensions: 4
1
⁄4" W x 5
1
⁄4" H x 2
3
⁄4" D
Approvals: UL listed for US and Canada, Temperature
Indicating and Regulating Equipment.
Power Supply: 120/60/1 VAC, 12 amps maximum
Relays: Boiler Relay 1 amp @ 24 VAC
Circulator Relay
1
⁄3 HP (6 FLA, 36 LRA)
Thermostat: 24 VAC Class 2 Output
Sensors: NTC thermistor, 10 kΩ @ 77°F
(25°C ±0.2°C) ß=3892
Outdoor Design Temp.: -30°F to 40°F (-35°C to 5°C)
Boiler Minimum: 70°F or 140°F (21°C or 60°C)
Differential: 10°F or 20°F (6°C or 12°C)
WWSD: 70°F (21°C), blinks TSTAT light when >70°F
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 75°C. Failure to follow this instruction 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.
TEMPERATURE RESISTANCE
°F °C
Ω
-30 -34 234,196
-20 -29 165,180
-10 -23 118,018
0 -18 85,362
10 -12 62,465
20 -7 46,218
TEMPERATURE RESISTANCE
°F °C
Ω
30 -1 34,558
40 4 26,099
50 10 19,900
60 16 15,311
70 21 11,883
80 27 9,299
TEMPERATURE RESISTANCE
°F °C
Ω
90 32 7,334
100 38 5,828
110 43 4,665
120 49 3,760
130 54 3,050
140 60 2,490
TEMPERATURE RESISTANCE
°F °C
Ω
150 66 2,045
160 71 1,689
170 77 1,403
180 82 1,172
190 88 983
200 93 829
Instruction Sheet
FuelMizer
™
SR501-OR-4 Switching Relay with Outdoor Reset
1
02-431
SUPERSEDES: June 1, 2012 EFFECTIVE: July 1, 2012
Plant ID# 9300-2871
ONE ZONE INSTALLATION W/O INDIRECT DHW
ONE ZONE
SWITCHING RELAY
WITH OUTDOOR RESET
SR 501OR-4
LED
I
NDICATORS
POWER
TSTAT
DHW
O
VERRIDE
BOILER
RELAY
NH
INPUT
120 VAC
ZONE 1
120 VAC
NH
6
AMP
X
R
BOILER TSTAT
W
CR
W
DHW
OUTDOOR
S
ENSOR
SUPPLY
S
ENSOR
X
DESIGN OUTDOOR
TEMPERATURE
FOR 180°F SUPPLY
TEMPERATURE
O
FF
-30
-
20
0
-10 10
2
0
4
0
30
ON
SW1
OFF
SYSTEM
CIRCULATOR
(OPTIONAL)
N
H
POWER
INPUT
(120 VAC)
2
4 VAC
THERMOSTAT
BOILER
CONTROL
OUTDOOR
SENSOR
B
OILER
SUPPLY
SENSOR
POT1
MULTI-ZONE INSTALLATION WITH ZONE CONTROL, WITH INDIRECT DHW
ONE ZONE
S
WITCHING RELAY
WITH OUTDOOR RESET
SR 501OR-4
LED
I
NDICATORS
POWER
T
STAT
DHW
OVERRIDE
BOILER
RELAY
NH
I
NPUT
120 VAC
Z
ONE 1
120 VAC
NH
6
AMP
X
R
BOILER TSTAT
W
CR
W
DHW
OUTDOOR
SENSOR
SUPPLY
SENSOR
X
DESIGN OUTDOOR
TEMPERATURE
FOR 180°F SUPPLY
TEMPERATURE
OFF
-
30
-20
0
-10 10
20
40
3
0
ON
SW1
OFF
S
YSTEM
CIRCULATOR
(OPTIONAL)
N
H
POWER
INPUT
(120 VAC)
BOILER
C
ONTROL
OUTDOOR
SENSOR
BOILER
SUPPLY
SENSOR
P
OT1
1234
Z
ONE 1
1234
Z
ONE 2
1234
Z
ONE 3
E
XISTING
Z
ONE VALVE CONTROL
POWER IN
24 VAC
N/O COM
N
/C
PUMP END
S
WITCH
FUSE
5 AMP
ZONE 3 PUMP
E
ND SWITCH
T
HERMOSTATS
(24VAC)
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
P
OWER
LED
INDICATORS
ZONE 1 ZONE 2 ZONE 3
ISOLATED
XX
RW
RW RW
END SWITCH THERMOSTATS
PRIORITY
24 VAC ZONE VALVES
PRIORITY
XX
ZONE 3
P
RIORITY
OFF
ON
CCC
2 WIRE ZONE VALVE
(NO END SWITCH)
MUST USE JUMPER
TACO 3 WIRE
ZONE VALVE
1
2
3
JUMPER
3 & 4
T
ACO 3 WIRE
ZONE VALVE
1
2
3
DHW
AQUASTAT
A
CONTROL STRATEGY:
Outdoor Reset:
In order to properly control a hot water heating system, the heat sup-
plied to the building must equal the heat lost by the building.
• The heat supplied to a building is proportional to the temperature of
the supply water and the surface area of the heating element. A
small surface area such as baseboard radiators requires a higher
water temperature than a larger surface area such as radiant floors.
• The heat lost from a building is dependent on the outdoor tem-
perature, as well as other factors. As the outdoor temperature
drops, the building heat loss increases.
Reset Ratio:
Operation of a hot water heating system can generally be improved by
modulating the supply water temperature as the outdoor temperature
changes. Using this approach, the heat lost from the building is
matched by the heat input to the building. The SR501-OR boiler reset
control utilizes a reset ratio to set the relationship between outdoor
temperature and supply water temperature. The reset ratio determines
the amount the supply water temperature is raised for every 1° drop in
outdoor air temperature, and it is determined from the starting point
and the system design conditions. In order for the control to automat-
ically determine the reset ratio, outdoor design conditions must be
established. This is usually the typical coldest outdoor temperature
or it can be set by using ASHARE standards for Design Outdoor
Temperature for specific geographic locations.
APPLICATION:
The SR501-OR is a microprocessor-based control designed to regulate
the supply water temperature of a single boiler, based on the outdoor
temperature. The SR501-OR is a boiler reset control and switching relay
in one unit. The SR501-OR is ideal for retrofit application, but may also
be used in new installations as well.
The SR501-OR includes functions such as automatic reset ratio calcu-
lation, warm weather shut down (WWSD), minimum boiler temperature
setting, and boiler differential setting. The control also has boiler sensor
and outdoor sensor error checking.
40
30
20
10
0
-10
-20
-30
70
-20
90
130
110
150
170
180
190
210
90 80 70 60 50 40 30 20 10 0 -10
OUTDOOR TEMPERATURE (°F)
BOILER SUPPLY TEMPERATURE vs. OUTDOOR TEMPERATURE (°F)
FOR OUTDOOR DESIGN TEMPERATURES
BOILER SUPPLY TEMPERATURE (°F)