Weil-McLain PFG-7 manual Boiler piping connections to the heating

PFG Series 7 Gas-fired Water Boiler — Boiler Manual

Boiler piping connections to the heating		4. Expansion tank installations.
system (refer to piping diagrams, Page 7)		a) Closed type expansion tanks - connect from the ¾” N.P.T.
	Failure to properly pipe the boiler may result in	expansion tank tapping on the left end section (located just
		behind the supply outlet tapping) to the expansion tank using
	improper operation and damage to the boiler or	¾” N.P.T. piping. Any horizontal expansion tank piping must
	building.	pitch upward toward the tank at least 1 inch for each 5 feet of
These boilers are provided with built-in air elimination sys-		piping.
		b) Diaphragm type expansion tank - may be located anywhere in
tems.
1. Install relief valve vertically in top ¾” tapping in right end section.		the system, preferably near the boiler.
			A manual or automatic type air vent must be
See WARNING following.
			installed in the ¾”N.P.T. tapping when a diaphragm
	To avoid water damage or scalding due to relief
			type tank is used.
	valve operation:	The most common cause of lime deposits in boilers is inadequate
• Discharge line must be connected to relief valve
		expansion tank volume. If the expansion tank is too small, system
	outlet and run to a safe place of disposal. Terminate	water is lost from the relief valve and make-up water is added
	the discharge line to eliminate possibility of severe	through the fill valve. Eventual section failure will result.
	burns should the valve discharge.	5. Connect the system supply piping to the supply outlet tapping on
• Discharge line must be as short as possible and be		the left end of the boiler. See Figure 2a for minimum pipe size.
	the same size as the valve discharge connection	6. Connect the system return piping to the return tapping on the right
	throughout its entire length.	end of the boiler. See Figure 2a for minimum pipe size.
• Discharge line must pitch downward from the valve		7. Install drain valve provided with boiler on left side. The installer
	and terminate at least 6”above the floor drain where	must provide a drain cock to drain the right (return) side of the
	any discharge will be clearly visible.	boiler and its connecting piping. The drain cock on the left side of
• The discharge line shall terminate plain, not thread-		the boiler will not fully drain the right side.
		8. Low water cut off:
	ed, with a material serviceable for temperatures of
	375 °F or greater.	a) Must be installed on any PFG boiler if the boiler is located above
• Do not pipe the discharge to any place where freez-		radiation level.
	ing could occur.	b) Must be installed on all PFG-8 boilers to meet ASME specifica-
• No shutoff valve shall be installed between the		tions (low water cut-off not supplied by Weil-McLain).
		c) May be required by certain state, local or territorial codes or
	relief valve and boiler, or in the discharge line. Do
	not plug or place any obstruction in the discharge	insurance companies.
	line.	If a low water cut-off is required, use a control designed especially
• Failure to comply with the above guidelines could		for water installations. An electrode probe type low water cut-off
	result in failure of the relief valve to operate, result-	may be located in a tee in the supply line above the boiler.
		9. If the system is to be ASME inspected and approved, an additional
	ing in possibility of severe personal injury, death or
	substantial property damage.	high temperature limit is needed. Purchase and install the control
• Test the operation of the valve after filling and pres-		in the supply outlet piping to the boiler.
	surizing system by lifting the lever. Make sure the
	valve discharges freely. If the valve fails to operate
		Figure 2a Minimum recommended pipe sizes
	correctly, replace it with a new relief valve.
			(Supply and return sizes refer to minimum size of
2. Install pressure-temperature gauge in tapping provided in left end
			pipe connected to the boiler for 20°F temperature
section.
			drop between supply and return.)
3. This boiler is for forced hot water circulation only. The circulator and
expansion tank must be selected and sized according to the design
requirements of the system.
a) Size and install circulator. Can be installed on supply or return
piping
b) Size expansion tank to handle the volume of water in the sys-
tem.

Part Number 550-110-641/0605