THERM-X-TROL ST-80V Expansion Tank (44 Gallon Volume) Zoom

THERM-X-TROL ST-80V Expansion Tank (44 Gallon Volume)


Brand: Amtrol

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Application: Plumbing
Tank Volume: 44 Gallons
Max Accept. Factor: 0.77
Connection Size: 1-1/4"
Max Pressure (PSI): 150
Temperature Range (F): 200°F MAX
Connection Type: Threaded
Height (Inches): 36
Diameter (Inches): 22"
Material: Steel
Weight (lbs): 69 lbs
Warranty: 5-Year Limited Warranty

Description for Amtrol 147N131

With modern plumbing codes mandating backflow prevention, thermal expansion can cause pressure buildup in domestic water systems. When demand is put upon a potable water system, hot water is drawn from the water heater. Cold water from the supply line enters the water heater to replenish it. The cold water is heated to replace the hot water used. With the installation of a backflow preventer, check valve or pressure reducing valve on the supply line, the water heater and the system piping form a closed plumbing system under pressure. As the water is heated, thermal expansion occurs. Pressure increases until the relief valve opens and the expanded water spills from the water heater. This spillage results in wasted energy and a potential safety hazard.

The THERM-X-TROL is designed to eliminate this problem by providing control of maximum pressures at a level below the relief valve setting. It also provides an additional space in the system to accommodate the increased volume of water created by thermal expansion, returning it to the system when hot water delivery is demanded. Maximum pressure is kept well below the relief valve setting by the THERM-X-TROL, with its pre-charged air cushion that is separated from system water. The relief valve does not open, therefore spillage is eliminated.

THERM-X-TROL ST-80V Expansion Tank (44 Gallon Volume)

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  • THERM-X-TROL ST-80V Expansion Tank (44 Gallon Volume)


    For the Modle ST-5, the product literature says the tank must be installed vertically. Does it matter which side is up??
    Asked on 2/26/2011 by Andy from Newe Jersey

    1 answer



      It does not.

      Answered on 2/28/2011 by PexSupply Staff from NY
  • THERM-X-TROL ST-80V Expansion Tank (44 Gallon Volume)


    What size of expansion chamber do I need with a 40 gal. 40 k btu hot water tank?
    My system has a booster pump, starts at 40 psi and cuts out at 60 psi. my original pump died so I replaced it with a different make and model. I installed the new pump and 3 days later I come home to a flooded basement! On start up of new pump the pressure built up to 60 psi and shut off, I checked for leaks the first couple days and found none. then I find that my reinforced flexible hose(125 psi rating I have about 2 ft on each side of the pump) had burst on the outlet side of the pump. After some time I did a test with a new hose installed, pump shut off at 60 psi as before then after about 15 min. the pressure had built up to 90 psi and was still climbing.I turned the pump off and have been running my system in by-pass since then. I now understand that I need a expansion tank. My original pump was a variable frequency drive, and my new pump is not. Might have something to do with it.
    Asked on 11/29/2010 by Hutch

    1 answer

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