Install Instructions

Closed-type expansion tank:
DO NOT use a closed-type tank if connect-
ing to a water heater that is equipped with an
automatic air vent.
Figure 43 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 fitting. Slope any horizontal piping a minimum of
1 inch per 5 feet of horizontal pipe.
Always use a tank fitting such as the B&G Tank-trol or Taco
Taco-trol (shown). The fitting reduces gravity flow of water
in the piping to the tank, avoids air bubbling through the
tank water, and provides the proper fill 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-type expansion tank—Follow tank
manufacturer’s instructions for filling 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 pres-
sure of system, after temperature expansion
above cold fill pressure, should not exceed
24 PSIG to avoid weeping of relieve valve.
&IGURE
Pressure drop through %#/ heat
exchanger (graph and table)
ECO 70 or 110 ECO 155
Flow Rate
(GPM)
Head Loss
(ft. w.c.)
Flow Rate
(GPM)
Head Loss
(ft. w.c.)
3.0 0.11 7.0 2.19
5.0 0.30 9.0 2.51
6.5 0.51 11.0 2.91
8.0 0.77 13.0 3.39
10.0 1.20 14.5 3.81
Direct Connect System Piping (continued)
&IGURE Piping to closed -type expansion tank
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
0246810121416
Pressure Drop (ft. w.c.)
Flow Through Heat Exchanger (GPM)
70/110 Models 155 Model
155
70/110
Part number 550-142-122/0513
38
TM
GAS-FIRED WATER BOILER — Boiler Manual