GPM
T
P FT. GPM
T
P FT.
GPM
T
P FT. GPM
T
P FT.
182/
181
45
7
9.2
20
15
1.8
1-1/2"
260/
261
45
10
9.4
20
22
1.9
1-1/2"
330/
331
45
12
9.6
20
28
1.9
1-1/2"
400/
401
45
15
9.8
20
33
2.0
1-1/2"
514
90
9
9.0
40
21
1.8
2"
624
90
12
9.5
40
26
1.9
2"
724
90
13
10.0
40
30
2.0
2"
824
90
15
10.5
40
34
2.1
2"
926
90
17
11.0
40
38
2.2
2-1/2"
200
8
9.7
90
17
2.1
3"
962
90
18
11.0
40
40
2.2
2-1/2"
200
8
9.7
90
18
2.1
3"
1083
90
20
12.0
45
40
3.1
2-1/2"
200
9
10.3
90
20
2.3
3"
1125
90
21
12.0
47
40
3.3
2-1/2"
200
9
10.3
90
20
2.3
3"
1178
90
22
12.5
49
40
3.8
2-1/2"
200
10
11
90
21
2.4
3"
1223
90
22
12.5
51
40
4.0
2-1/2"
200
10
11
90
22
2.4
3"
1287
90
24
13.2
53
40
4.5
2-1/2"
200
11
11.7
90
23
2.5
3"
1336
90
24
13.2
55
40
4.9
2-1/2"
200
11
11.7
90
24
2.5
3"
1414
90
26
14.0
58
40
5.8
2-1/2"
200
12
12.2
90
26
2.7
3"
1468
90
27
14.0
61
40
6.4
2-1/2"
200
12
12.2
90
27
2.7
3"
1571
90
29
14.5
65
40
7.5
2-1/2"
200
13
13
90
29
2.8
3"
1631
90
30
14.5
68
40
8.3
2-1/2"
200
13
13
90
30
2.8
3"
1758
90
32
15.4
73
40
10.0 2-1/2"
200
14
14.7
90
32
3.0
3"
1826
90
34
15.4
76
40
10.8 2-1/2"
200
15
14.7
90
33
3.0
3"
2100
200
17
14.8
90
39
3.2
3"
400
9
18
180
19
4.0
4"
2500
200
21
15.8
103
40
4.4
3"
400
10
18.8
180
23
4.1
4"
3001
200
25
16.7
124
40
6.7
3"
400
12
19.5
180
27
4.3
4"
3500
200
29
17.5
145
40
9.5
3"
400
14
20.5
180
32
4.5
4"
4001
200
33
18.7
166
40
13.0
3"
400
16
21.5
180
36
4.7
4"
BOLD TYPE
indicates Low NOx models.
GPM Flow rates limited by maximum acceptable velocity through heat exchanger tubes. May be increased by 10% for
closed heating systems.
MAXIMUM AND MINIMUM FLOW RATES
1-PASS HEAT EXCHANGER
2-PASS HEAT EXCHANGER
MODEL
SIZE
HDR
CONN
HDR
CONN
MAX
MIN
MAX
MIN
Piping—Heating Boilers
Raypak recommends that all high points be vented
and that purge valves and a bypass valve be installed.
A boiler installed above radiation level must be provid-
ed with a low water cut-off device. The boiler, when
used in conjunction with a refrigeration system, must
be installed so that the chilled medium is piped in par-
allel with the boiler with appropriate valves to prevent
the chilled medium from entering the boiler.
Raypak strongly recommends the use of primary/sec-
ondary piping for all H boilers, as shown in the
following piping diagrams. System flow must exceed
the flow through the boiler at all firing rates.
Hot water heating systems all have unique levels of
operating diversity that must be accounted for in the
system design. The system should always include
adequate system flow in excess of the connected boil-
er flow for proper operation. Where the system flow
may drop below the connected boiler flow a
buffer/decoupler may be needed. Failure to design for
adequate flow (i.e. bypasses, 3 way control valves,
flow limiting balance devices, buffer tanks, etc.) will
result in boiler short cycling and may reduce boiler life.
Always contact your local Raypak representative for
system design assistance to avoid these issues.
Recommended Purge Manifolds for
Typical Hydronic System Hookups
The boiler piping system of a hot water heating boiler
connected to heating coils located in air handling units
where they may be exposed to refrigerated air circulat-
ing, must be equipped with flow control valves or other
automatic means to prevent gravity circulation of the
boiler water during the cooling cycle.
Temperature & Pressure Gauge
The temperature & pressure gauge is standard equip-
ment on all hydronic heating and hot water supply
boilers. All temperature & pressure gauges are factory
mounted in the in/out header except for residential
boilers, Models 181-401. On these models the temper-
ature & pressure gauge is shipped loose for field
installation, and located in the outlet water connection.
All fittings required to mount gauge to piping system
are supplied by others.
Table H: Maximum and Minimum Flow Rates
17
