Closed-Type Expansion Tank - Weil-McLain Series 2 Manual

® S
ERIES
Direct Connect System Piping

Closed-type expansion tank:

DO NOT use a closed-type tank if connecting
to a water heater that is equipped with an
automatic air vent.
Figure 50 shows suggested piping when using a closed-type
expansion tank, in which the air is directly in contact with
tank water.
Connect piping (½" or ¾") from the air separator outlet to
the tank fi tting. Slope any horizontal piping a minimum of
1 inch per 5 feet of horizontal pipe.
Always use a tank fi tting such as the B&G Tank-trol or Taco
Taco-trol (shown). The fi tting reduces gravity fl ow of water
in the piping to the tank, avoids air bubbling through the
tank water, and provides the proper fi ll height in the tank
Correct all leaks in the system or tank piping.
Leaks allow air to escape from the system and
will cause water-logging of the tank. This will
result in water loss through the boiler relief
valve due to over-pressurization. NEVER use
an automatic air vent in a system equipped
with a closed-type expansion tank. The air
removed from the system will cause water-
logging of the expansion tank.
Closed-ty pe expansion tank—Follow
tank manufacturer's instructions for fi lling
the tank. Typical tank sizing provides for
approximately 12 PSIG when the tank
is filled to the normal level and system
water is cold. Note that boiler relief valve
is set for 30 PSIG. Operation pressure of
system, after temperature expansion above
cold fill pressure, should not exceed 24
PSIG to avoid weeping of relieve valve.
Figure 49
Pressure drop through ECO heat
exchanger (graph and table)
ECO 70 or 110
Flow Rate Head Loss
*30 IW ZF
3.0 0.11
5.0 0.30
 0.51
8.0 0.77
10.0 1.20
44
2
-
G
AS FIRED WATER BOILER
ECO 155
Flow Rate Head Loss
*30 IW ZF
7.0 0.39
9.0 
11.0 0.97
13.0 1.35
14.5 
— Boiler Manual
(continued)
Figure 50
Piping to closed-type expansion tank
1.80
1.60
1.40
1.20
1.00
0.80
70/110
0.60
0.40
0.20
0.00
0 2 4
Flow Through Heat Exchanger (GPM)
155
6 8 10 12
70/110 Models
155 Model
Part number 550-142-190/1218
14 16