Weil-McLain SlimFit 2 Series Manual page 16

SlimFit Series 2
®
Install water piping
Expansion tank and make-up water
1. Ensure expansion tank size will handle boiler and system water
volume and temperature. See page 116 for boiler water content.
Undersized expansion tanks cause system water to be
lost from relief valve and make-up water to be added
through fill valve. Eventual boiler failure can result due
to excessive make-up water addition.
2. Tank must be located as shown in this manual, or following rec-
ognized design methods. See tank manufacturer's instructions
for details.
3. Connect the expansion tank to the air separator only if the separa-
tor is on the suction side of the pump. Always install the system fill
connection at the same point as the expansion tank connection
to the system.
4. Most piping drawings in this manual show diaphragm expansion
tanks. See Figure 14 for piping from air separator to expansion
tank and make-up water line using a closed-type expansion tank.
5. Most chilled water systems are piped using a closed-type tank, as
shown in Figure 20, page 21.
Diaphragm (or bladder) expansion tank
1. (Figure 14) Always install an automatic air vent on top of the air
separator to remove residual air from the system.
When using diaphragm or bladder tanks only — when the
boiler is installed above the system main piping, install an
automatic air vent in the top of the outgoing boiler piping
to prevent air pocketing.
The expansion tank needs to be pre-charged to the
required system fill pressure before being connected to
the system.
Closed-type expansion tank
1. See Figure 15, Alternate, for piping connections when using a
closed-type expansion tank.
2. Pitch any horizontal piping up towards tank 1 inch per 5 feet of
piping. Connect to tank with at least ¾" piping to allow room for
air to rise.
DO NOT install automatic air vents on closed-type expan-
sion tank systems. Air must remain in the system and
return to the tank to provide its air cushion. An automatic
air vent would cause air to leave system, resulting in
water-logging the expansion tank.
16
commercial condensing gas
(continued)
— Boiler Manual
-
fired water boiler
Figure 14
Expansion tank piping — diaphragm-type
expansion tank
7
To system
Figure 15
Expansion tank piping — closed-type
expansion tank
To system
1 Diaphragm-type expansion tank.
2 Closed-type expansion tank.
3 Make-up water line.
4 Fill valve, typical.
5 Air separator.
6 Tank fitting.
7 System pump (when used).
8 Automatic air vent.
8
From boiler/system
5
4
3
1
2
6
3
7
From boiler/system
8
Part number 550-100-561/0224