
Pre-Installation
1 Ensure expansion tank is sized properly for application (Figure 1).
2. Remove plastic cap from air valve.
3. With tank empty of water, adjust air precharge to match cold water
supply pressure.
4. Replace and tighten plastic cap on air valve.
5. Therm-X-Trol®ST-5, ST-8, ST-12 only: Insert Turbulator™
into connector.
FAILURE TO PROPERLY SEAL VALVE CAP
WILL RESULT IN LOSS OF PRECHARGE
CAUSING PRODUCT TO FAIL.
Installation
1. Install the expansion tank on the cold water supply line to the water
heater at a point between the water heater and backflow preventer or
other one-way device (Figure 2).
Mount tank vertically in downward position only.
Ensure the piping can support the entire weight
of the tank when full of water.
Models ST-25V through ST-210V are floor
standing and may not be hung from the piping.
2. Once the expansion tank is installed, check the cold water supply line
for any leakage. Make repairs if necessary.
3. Before the initial firing of the water heater, open any hot water fixture
and draw water until all air is removed from the system. Turn the water
heater temperature control to desired ending temperature (see water
heater instructions). Do not set temperature higher than the expansion
tank maximum.
4. To relieve initial thermal expansion, momentarily open a hot water
faucet. Continue until water heater aquastat temperature is satisfied.
Once heater is at its operating range, no further bleeding of expanded
water is required.
5. The water heater and expansion tank will now be operational. The
expansion tank will control pressure increases caused by thermal
expansion to a level below the water heater relief valve setting.
Maintenance
A professional plumber should check the complete system, including the
expansion tank, yearly and more frequently as the system ages. Checking
the precharge allows a small quantity of air to escape and can result in an
insufficient air charge. Always check the precharge while the tank is isolated
and empty of water, and be sure to maintain the proper precharge whenever
the tank is inspected. Monitor the tip of the inspection cap for discoloration
(Figure 3) in addition to regular product inspection. Contact the installer or
a plumbing professional if inspection cap is discolored; tank replacement
required. Do not rely on cap as sole indication of tank condition.
Warranty
ST-5 through ST-25V Models: Five (5) Year Limited Warranty
ST-30V through ST-210V Models: One (1) Year Limited Warranty
T-5 through T-12 Models: One (1) Year Limited Warranty
Visit www.amtrol.com for complete warranty details.
© 2017 AMTROL Inc. Part #: 9015-942 (03/17)
1400 Division Road, West Warwick, RI USA 02893
T: 800.426.8765 F: 800.293.1519
www.amtrol.com
Residential sizing based on: 40°F incoming water temperature; 150 psi T&P safety relief valve; Pre-charge equal to static supply pressure.
Models: ST-5, ST-8, ST-12, T-5, T-8, T-12 for residential use only
For larger commercial applications: Visit amtrol.com, download the AMTROL App or contact Technical Support at 401.535.1216.
Figure 1.
Expansion Tank Volume (Gal.)
Maximum Temperature Setting 180°F
Water Heater
Size
(gals.)
Static Supply Pressure (psig)
40 60 80
40 3.2 3.2 3.2
50 3.2 3.2 4.4
60 3.2 4.4 10.3
80 4.4 10.3 10.3
120 10.3 10.3 10.3
Expansion Tank Volume (Gal.)
Maximum Temperature Setting 160°F
Water Heater
Size
(gals.)
Static Supply Pressure (psig)
40 60 80
40 2.0 2.0 3.2
50 2.0 3.2 3.2
60 3.2 3.2 4.4
80 3.2 4.4 10.3
120 4.4 10.3 10.3
Expansion Tank Volume (Gal.)
Maximum Temperature Setting 140°F
Water Heater
Size
(gals.)
Static Supply Pressure (psig)
40 60 80
40 2.0 2.0 2.0
50 2.0 2.0 2.0
60 3.2 3.2 3.2
80 3.2 3.2 4.4
120 4.4 4.4 10.3
PLEASE READ THE FOLLOWING INSTRUCTIONS CAREFULLY
IMPORTANT GENERAL SAFETY INFORMATION -
ADDITIONAL SPECIFIC SAFETY ALERTS APPEAR IN THE FOLLOWING INSTRUCTIONS.
Models up to
10.3 gallons
Figure 3.
Clear / White
Normal
Operation
Discolored
Replace
Tank
InSight™Service Indicator Cap (ST-5, ST-8 and ST-12 Inline models only)
(Patent Pending)
Figure 2.
In-Line Models Stand Models
Thermal
Expansion
Tank
Cold
Water
Supply
Backflow Preventor, Check Valve
or Pressure Reducing Valve
Hot Water
T & P
Relief
Valve
Water
Heater
Turbulator™Installation (ST-5, ST-8, ST-12 only)
Press Turbulator fully
into connector prior
to installing tank.
3/4” Threaded Tee
Turbulator
Tank Connector
Thermal
Expansion
Tank
Hot Water
T & P
Relief
Valve
Water
Heater
Cold
Water
Supply
Backflow Preventor Check Valve
or Pressure Reducing Valve
Remove cap and
charge to cold
supply pressure.
Replace cap
and tighten until
flush with tank.
Precharge Adjustment