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6. The use of a Hartford Loop in all installations is
recommended to ensure reliability of the system. A
check is required on the pump discharge of all
pumped return systems.
7. On pumped return systems, install a globe valve after
the pump to allow throttling of the pump discharge.
The pressure downstream of the boiler cock should
be no more than 5 psig above the boiler operating
pressure.
NOTICE
Always locate the steam supply take-off of the main
header between the equalizer and the last boiler
supply riser. Locating the steam supply between the
risers will cause a bullhead tee and cause water
carryover into the system.
8. Pipe the Hartford Loop such that the top of the close
nipple is 2 to 4 inches below the boiler normal water
line.
9. If the boiler feed pump discharge piping is elevated
at any point above the boiler water line, install
spring-loaded check valves at both the pump
discharge and at the connection to the boiler.
Table 4.1:
Steam Supply and Header Pipe Sizing
Number of
Boiler
Supply
Supply
Model
Size (NPS)
Connections
63-03L
1
2
63-03
1
2
1
2-1/2
63-04L
2*
2*
1
2-1/2
63-04
2*
2*
1
3
63-05L
2*
2*
1
3
63-05
2*
2*
1
3
63-06
2*
2-1/2*
1
3
64-07
2*
2-1/2*
64-08
2
2-1/2
64-09
2
3
64-10
2
3
64-11
2
3
64-12
2
3
*Dual supplies may be used in lieu of larger single supply on
63-04L through 64-07 as indicated.
Header
Equalizer
Evaporation
Size (NPS)
Size (NPS)
Rate (GPM)
2
1-1/4
0.11
2
1-1/4
0.15
2-1/2
1-1/4
0.19
2-1/2
1-1/4
0.23
3
1-1/4
0.27
3
1-1/4
0.31
3
1-1/4
0.37
3
1-1/2
0.45
4
1-1/2
0.52
4
1-1/2
0.60
4
1-1/2
0.67
4
1-1/2
0.75
5
1-1/2
0.82
D. STEAM BOILER INDIRECT WATER
HEATER PIPING
1. See Figure 4.5 for typical installation.
2. Install Boiler Water Temperature Limit Control in 1"
Tee on supply connection (same side of boiler as low
water cut-off). Set Limit at 160°F to avoid steam
generation during periods when only the domestic
water is calling for heat.
3. Install circulator and strainer in supply piping. Install
check valve to prevent gravity circulation.
NOTICE
Maintain water level near normal water line to avoid
steam generation during periods when only the
domestic water is calling for heat.
Tank performance reduced when supplied by steam
boiler.
Figure 4.5: Typical Steam Boiler Indirect
Water Heater Piping
E. STEAM BOILER PIPING - MULTIPLE
BOILERS
Refer to the PB Heat Steam Installation Survey and
Hydronics Institute Residential Hydronic Heating
Installation Design Guide for guidance on multiple boiler
installations.
BOILER PIPING
15
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