A.O. Smith HW 610 ユーザーズマニュアル

18

All modern hydronic type boilers are exceptionally fast heating units.  

The  low  water  volumes  in  relation  to  firing  rates  require  special 

attention to water flow rates for smooth, efficient operation. These 

considerations for the A. O. Smith copper heat exchanger boilers 

are covered below.

Conventional 20

0

F (10

0

C) drop in systems for a fully loaded boiler 

will maintain the following approximate flow rates:

HW-300

23 (87)

HW-399

30 (114)

HW-420

35 (132)

HW-520

39 (148)

HW-610/670

46 (175)

Figure 7 on page 14 shows a typical installation of the boiler with pipe 

sizing and circulator selected by the installer to provide adequate 

water flow whenever the boiler is firing.

In a system with several large zones of which any might be smaller 

than  approximately  1/3  of  the  system  should  include  a  hydronic 

balancer  as  shown  in  Figure  7. The  balancer  connects  between 

the  system  supply  and  the  return  line  before  the  circulator  inlet. 

Adjustment of the balancing cock should permit adequate boiler flow 

rate when only the smallest zone is in operation.

Attention should be given to balancing inputs and water flow rates 

where wide variations of system flow rates can occur.

The recommended minimum flow rates that will result in approximately 

50

0

F (30

0

C) temperature rise across the boiler are as follows:

HW-300

9 (34)

HW-399

12 (45)

HW-420

14 (53)

HW-520

16 (61)

HW-610

18 (69)

HW-670

20 (76)

If system flow rate is unknown, or if zoning creates extreme variations 

in flow rates, the boiler should be installed as shown in Figure 11 on 

this page for A. O. Smith LINEAR-TEMP installations.

 

A.  New Installations

A. O. Smith LINEAR-TEMP systems have been designed to provide 

efficient, trouble-free operation of the boiler sizes covered in this 

manual with any of the following conditions:

 

a.  Unknown system flow rate

 

b.  Varying flow rate as with zoned systems

 

c.  Multiple boiler installations

Figure 11 on this page shows piping and accessory arrangement 

for a boiler pumped independent of the primary system mains.  Pipe 

sizing and boiler loop pump selection data are shown in Table 6 for 

several different temperature rises across the boilers.

Total heating requirements for the building can be supplied by a 

series of boiler loops all connecting to a common pipe joining the 

system supply and return mains. The supply and return branches of 

each boiler loop must join the common pipe only a short nipple length 

apart. The different sets of branches should be installed reasonably 

close  together,  but  not  necessarily  to  the  short  nipple  length  as 

required for the supply and return of each set. These branches may 

be made with tees or with welded connections.

The installer is reminded that the total boiler flow rates need not 

match the system flow rate.

 20 (10)

 30 (15)

 30 (15)

40 (20)

23

15

15

11

1-1/2" PR

150

125

100

2"

1-1/2"

1-1/4"

1"

20 (10)

35 (15)

40 (20)

40 (20)

30

20

15

15

60-13

1-1/2" HV

150

125

2"

1-1/2"

1-1/2"

1-1/4"

20 (10)

35 (15)

40 (20)

40 (20)

32

21

16

16

60-13

1-1/2" HV

150

125

2"

1-1/2"

1-1/2"

1-1/4"

20 (10)

20 (10)

35 (17)

40 (20)

39

26

23

20

2-1/2"

1-1/2" HV

1-1/2" HV

150

2-1/2"

2"

1-1/2"

1-1/2"

20 (10)

30 (15)

35 (17)

40 (20)

51

34

29

25

60-13

2-1/2"

2"

1-1/2" HV

3"

2-1/2"

2"

1-1/2"

NOTE:   Pipe loop sizes and pump selections based on 

 

 50 equivalent feet of pipe and fittings.

*All pump sizes listed are B & G model numbers.