Install Instructions

Part number 550-100-191/0917
43
®
gas-fired water boiler — 70/110/155 Boiler Manual
To avoid water damage or scalding due to
relief valve operation, as per local or state
codes
:
Install relief valve ONLY with the spindle vertical,
as shown in illustrations in this manual.
Discharge line must be connected to relief valve
outlet and run to a safe place of disposal. Terminate
the discharge line in a manner that will prevent
possibility of severe burns or property damage
should the valve discharge. Locate away from the
top of the boiler.
Discharge line must be as short as possible and be
the same size as the valve discharge connection
throughout its entire length.
Discharge line must pitch downward from the
valve and terminate at least 6" above the fl oor drain
where any discharge will be clearly visible.
The discharge line shall terminate plain,
not threaded, with a material serviceable for
temperatures of 375 °F or greater.
Do not pipe the discharge to any place where
freezing could occur.
No shutoff valve shall be installed between the
relief valve and boiler, or in the discharge line. Do
not plug or place any obstruction in the discharge
line.
Test the operation of the valve after filling and
pressurizing system by lifting the lever. Make sure
the valve discharges freely. If the valve fails to operate
correctly, replace it with a new relief valve.
Failure to comply with the above guidelines could
result in failure of the relief valve to operate,
resulting in possibility of severe personal injury,
death or substantial property damage.
Instal l r e lief valve
1. Install relief valve in 1" x 1" x ¾" (for 70/110) or 1 ¼" x
1 ¼" x ¾" (for 155) reducing tee piped from boiler supply
( Figure 8, page 14 ).
2. Pipe the relief valve only as shown, in the location shown.
3. Connect discharge piping to safe disposal location, following
guidelines in the WARNING below.
System water piping methods
Head loss through boiler piping
See Figure 46 for the head loss through the boiler.
Use boiler head loss values to size pump after determining
other piping head loss values.
System circulator
1. Install a system circulator as shown in the piping diagram in
the Direct Connect System Piping section on page 45 .
2. If provided circulator does not meet flow requirement,
circulator must be supplied by the installer.
System circulator fl ow rates
1. Size circulators based on the fl ow rate required to achieve the
temperature rise or drop.
2. You can closely estimate the required fl ow through a circuit
by using the following formula, where TD is temperature rise
(or drop), FLOW is fl ow rate (in gpm), and BTUH is the heat
load for the circuit:
FLOW =
BTUH
—–—–—–—–
TD x 500
Examples:
Consider a system loop for a system with total heating input equal
to 210,000 Btuh. The desired temperature drop through the system
piping is 20°F. Then the required fl ow rate is:
FLOW =
210,000
—–—–—–—–
20 x 500
= 21 gpm
SIMPLIFIED:
For 20° temperature drop, FLOW = MBH / 10.
System circulator head requirement
1. The circulator must be capable of delivering the required fl ow
against the head loss that will occur in the boiler piping.
2. Determine the pipe size needed and the resultant head loss
using accepted engineering methods.
Figure 47 Piping to closed-type expansion tank
Direct Connect System Piping - Single Boiler System (continued)