GOLD CGa Gas-Fired Water Boiler
48 Part Number 550-110-593/1099
Service & maint. — annual start-up continued10b❏ Check/test . . . . . . .
Figure 27 Relief valve, typical
59343
circulation of air-saturated tank water back to
the system and prevents the air from bubbling
up through the water as it returns from the
system.
•Do not use automatic air vents in systems
with closed-type tanks. The air will escape
from the system instead of returning to the tank.
Eventually, the tank will waterlog and no longer
control pressurization. The boiler relief valve
will weep frequently.
Diaphragm- or bladder-type— welded gas tight
with a rubber membrane to separate the tank
pressurizing air and the water. May be located at
any point in the system, but most often found near
the boiler.
• Systems with this type of expansion tank
require at least one automatic air vent,
preferably located on top of an air eliminator,
as shown in examples in manual section 3,
pages 16-25.
2. If relief valve has tended to weep frequently, the
expansion tank may be waterlogged or undersized.
Closed-type tank — tank is most likely
waterlogged. Install a tank fitting if not already
installed. Then check fill level per fitting
manufacturer’s instructions. If fill level is correct,
check tank size against manufacturer’s instructions.
Replace with a larger tank if necessary.
Diaphragm- or bladder-type— first, check tank
size to be sure it is large enough for the system. If
size is too small, add additional tank(s) as necessary