Pentair MASTERTEMP 125 User Manual

MASTERTEMP 125 Pool and Spa Heater Installation and User’s Guide P/N 475114 Rev. F 8/2020
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Figure 24.
GND
L1
GROUND (GND )
L2
JUNCTION
BOX
L1
L2
BM
FL
F1
L1
TRANS
F
I
R
E
M
A
N
S
S
W
I
T
C
H
Fireman's Switch
Completes the heater
24 Volt AC Control
Board Circuit.
DO NOT connect this
circuit to Line Voltage!
YY
R
W
G
Y
Y
TERMINAL BOARD
TRANS
TRANS
FUSE
FUSE
L2
Time Clock or Remote
(Purchase Separately –
Supplies Power to
Circulator Pump)
24VA C
24 VA C
BK
O
O
BK
W
R
BK
R
W
12 Pin Receptacle
VAL
TH
IND
GND
24VAC 24VAC
FS
THERMISTOR
OPERATING CONTROL
DISABLE TOGGLE
ENABLE TOGGL
E
MEMBRANE PAD
CONNECTION
9
1
J6
Figure 25.
USE THE PROVIDED WATERPROOF WIRE NUTS WHEN CONNECTING THE POWER SUPPLY.
A time clock controlling the lter pump should have a low-voltage Fireman’s Switch that switches off the heater at
least 15 minutes before shutting off the pump.
1. - Remove the factory installed jumper from the Fireman’s Switch terminals.
- Connect wires between the Fireman’s Switch terminals on the heater and the relay. Connect wires from the
controller or timer to the Fireman’s Switch. Controller, timer or relay should be sized to handle 24VAC at 0.5
Amp (because it will be completing the 24VAC control board circuit on the heater as shown in Figure 31 (page
23). DO NOT apply line voltage to the Fireman’s Switch terminals. Use 18 gauge wire with a minimum 1.2
mm (3/64 in.) thick insulation rated for a temperature rise of at least 105° C.
- Knock-outs are provided to route the wires through the bottom of the control box and past the junction box.
2. To connect a 3-Wire Control:
- Connect wires between the control board terminals on the heater and the
external relays, as shown in Figure 31, on page 23. Use at least 2 relays per
heater, to allow for an “OFF setting” on each heater mode. Select relays
that can handle logic level switching. DO NOT apply line voltage to control
board terminals.
- Move jumper (as show in Figure 25) to enable external control and to disable
the heater membrane pad’s “Pool POOL/SPA buttons (the HEATER (ON/
OFF button control panel remains functional).
Section 1. Installation

Pentair MASTERTEMP 125 Specifications

General

BTU Output	125, 000 BTU/hr
Fuel Type	Natural Gas or Propane
Ignition System	Electronic
Minimum Flow Rate	20 GPM
Maximum Working Pressure	50 PSI
Efficiency	82%
Water Connections	1.5 inch
Certifications	ANSI Z21.56
Voltage	120V