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Table 5. Water Flow Requirements and Temperature Rise (boiler pump sizing reference)
SECTION 5
PUMP REQUIREMENTS
Table 6. Equivalent Feet and Head Loss
Model
Size
GPM
Equivalent Feet
of
¾”
Type M
Copper
Feet of Head
Loss
50
5
75
4.9
100
6.5
75
7.5
75
10.3
100
13.8
100
10
75
17.6
100
23.5
5.A Pump Sizing with Low Loss Header
and an Integral Pump
Models 125-200 are provided with a Low Loss Header
to ensure that the boiler always receives adequate
water flow for optimum efficiency, ease of installation
and long life. The Low Loss Header, with its integral
Boiler Pump, eliminates the need for by-pass piping
because it allows the system flow and the boiler flow
to be independent of each other without the cost
and complexity of a typical Primary / Secondary type
system. See Section 6.D
A Low Loss Header Kit is available for the model 50,
75, and 100 as an option for smaller systems that could
benefit from its use. See SECTION 12.C
Headloss is only calculated through the individual
zones for sizing of the system pump (s).
Zone Pump Size = GPM @Zone Feet of Headloss
(See Table 6)
5.B Pump Sizing without a Low Loss
Header
A typical residential pump creates enough GPM
(gallons per minute flow) for the average, properly-
designed, zone system for models 50 and 75. If a zone
exceeds 100 equivalent feet of 3/4” pipe, a pump may
not be large enough to overcome the resistance and
ensure proper water flow through the boiler.
Sizing the boiler / system pump requires the headloss
of the zone piping combined with the heat exchanger
headloss. Use Table 5 and 6 to approximate the head
loss for each zone and ensure the pump selection is
adequate. Compare to the manufacturer's pump curve
to ensure sufficient flow for the boiler.
Zone Pump Size = GPM @Zone Feet of Headloss
(See Table 6) + Boiler Headloss (See Table 5).
Primary/Secondary systems and boilers with LLH
systems can be used to avoid needing larger system
pumps.
Water Flow Requirements
Electrical
Data
All Sizes
with
Low Loss Header
without
Low Loss Header
Voltage
120 V
120 V
FLA
0.70 A
0.20 A
MCA
0.90 A
0.25 A
MOP
15 A
15 A
Minimum Clearances
Left + Right Sides
Front
Flue and Rear
Top
Size
inches
cm
inches
cm
inches
cm
inches
cm
ALL
4
10
2
5
6
15
20
51
Minimum
Clearances
from
Adjacent
Construction
Temperature Rise
15°F
8°C
20°F
11°C
25°F
14°C
Size
Flow Rate
Headloss
Flow Rate
Headloss
Flow Rate
Headloss
gpm
l/s
ft
m
gpm
l/s
ft
m
gpm
l/s
ft
m
50
5.3
0.3
0.3
0.1
4.0
0.3
0.2
0.1
3.2
0.2
0.1
0.1
75
8.0
0.5
0.6
0.2
6.0
0.4
0.3
0.1
4.8
0.3
0.2
0.1
100
10.7
0.7
1.3
0.4
8.0
0.5
0.7
0.2
6.4
0.4
0.5
0.2
125
*
13.3
0.8
2.2
0.7
10.0
0.6
1.3
0.4
8.0
0.5
0.8
0.2
150
*
17.0
1.1
2.5
0.8
12.8
0.8
1.8
0.5
10.3
0.6
1.2
0.4
200
*
22.8
1.4
5.0
1.5
17.0
1.0
3.1
0.9
13.7
0.9
1.9
0.6
*
Models 125-200 ship with a low loss header with integral pump, so a separate boiler pump does not need to be sized or fi eld-supplied.
NOTES:
1. Shaded area represents typical temperature rise.
2. gpm = water fl ow in gallons per minute.
3. l/s = water fl ow in liters per second.
4. ft = pressure drop (headloss) through the boiler in feet of water.
5. m = pressure drop (headloss) through the boiler in meters of water.
Sizing
Data
Size MBTU/h
kW
MBTU/h
kW
MBTU/h
kW
%
inches inches
50
50
14.7
42
12.6
37
10.8
84 1-1/4
3/4
75
75
22.0
63
18.8
55
16.1
84 1-1/4
3/4
100
100
29.3
84
24.9
73
21.4
84 1-1/4
3/4
125
125
36.6
105
31.1
91
26.7
84 1-1/4
3/4
150
150
44.0
126
37.2
110
32.2
84 1-1/4
3/4
200
199
58.3
168
49.2
146
42.8
84 1-1/4
3/4
116*
127*
141*
164
176
206
136*
148*
153*
191
202
237
Note: The Net AHRI Water Ratings shown are based on a piping and pickup allowance of 1.15.
*Add approximately 9 Lbs for unit with pump.
Weight
Lbs
Gas
Conn.
Water
Conn.
Net AHRI
Rating
Input
AHRI Certifi ed
Heating Capacity
Natural Gas
AHRI
Certifi ed
AFUE %
Shipping
Weight
Lbs
This boiler has a water tube design, and requires
correct water flow for proper operation and long life.
NOTE: Field Supply System / Zone pump(s) for all
models.
NOTE: If small zones are being installed with large
boilers, a buffer tank will help reduce short cycling
of the boiler and will enhance system performance.
(zone pump sizing reference)
M
INI-
T
HERM
JX
Residential Boilers
®
