Weil-McLain SlimFit Manual page 16

SlimFit
™
commercial condensing gas
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 126 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 recognized
design methods. See tank manufacturer's instructions for details.
3. Connect the expansion tank to the air separator only if the separator is
on the suction side of the pump. Always install the system fill connec-
tion 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 separa-
tor 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
-
fired water boiler
(continued)
Figure 14
To system
Figure 15
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
— Boiler Manual
Expansion tank piping — diaphragm-type
expansion tank
8
7
5
4
1
Expansion tank piping — closed-type
expansion tank
6
3
7
8
Part number 550-100-116/0713
From boiler/system
3
2
From boiler/system