User Guide

4
Monitron S2 Boiler Operation and Installation Instructions
Table 1. Lug Sizes
† ALUMINUM conductors may be used, lug size, conduit size, ampacity and all applicable
codes permitting. However, aluminum conductors may NOT be used for models over 32 Kw.
Table 2. Current Ratings
* For current values @ 208V, multiply current @ 240V by 0.867.
† Leg with the highest value of line current of an unbalanced 3-phase load.
‡ 125 VAC maximum rating of all hot conductors.
Table 3. Flow Switch Size Selection
* Both upstream and downstream of flow switch.
Model
No.
Flow Switch
McDonnell &
Miller No.
Pipe Size
Minimum
Length of
Straight Pipe*
mm inch mm inch
EH-40 FS8V 32 1-1/4 216 8-1/2
EH-8 thru
EH-35
FS4-3T3-1 25 1 165 6-1/2
Model Phase
Distribution
Block Wire
Size CU-AL†
Grounding
Lug Wire
Size CU
Neutral Lug
Wire Size
CU
EH-24 thru EH-40S2 1
1-250 CU
2/0-250 AL
6-2/0 6-2/0
EH-8 thru 20S2 1 6-2/0 CU-AL 6-2/0 6-2/0
EH-12 thru 40S2 3 6-2/0 CU-AL 6-2/0 6-2/0
The maximum wire size of the neutral should not exceed 12 AWG in order for 51 mm (2”)
conduit to accommodate incoming power feeder, plus the neutral wire and a ground conductor
for the larger models.
SINGLE PHASE 3 WIRE
120/208V, 120/240V‡
THREE PHASE, 4 WIRE
120/208V-WYE
CIRCUIT ONLY‡
Basic
Model
No.
Heater
Ampres*
@240V
FLA
@240V
Basic
Model
No.
Heater
Ampres†
@208V
FLA
@208V
EH-8 33 45
EH-9 38 49
EH-10 42 54
EH-12 50 62 EH-12 29† 41†
EH-15 63 74 EH-15 36† 48†
EH-16 67 79 EH-16 43† 55†
EH-18 75 87 EH-18 51† 63†
EH-20 83 95 EH-20 54† 66†
EH-24 100 112 EH-24 69† 69†
EH-25 104 116 EH-25 72† 72†
EH-28 117 129 EH-28 69† 81†
EH-30 125 137 EH-30 72† 84†
EH-32 133 145 EH-32 83† 83†
EH-35 146 158 EH-35 90† 90†
EH-38 158 170 – – –
EH-40 167 179 EH-40 108† 108†