How to Size a Water Expansion Tank
The size of a water expansion tank depends on various aspects of your water heating system and is basically a function of the size of the hot water boiler system and hydronic loop. Generally, the sizing of a tank is completed by the person or company who designed and installed your hot water boiler system. The tank should be large enough that when water is added to it the air inside is not compressed to a pressure that is more than the system can handle. The sizing is based on calculations that are specific to the type of tank. Does this Spark an idea?
Things You'll Need
- Acceptance factor chart
- Expansion factor table
- Specifications of your heating system
Instructions
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1
Obtain the following information concerning your hot water heating system: gallon capacity of your total water system, temperature of the water when the system is filled, average maximum operating temperature, minimum operating pressure and the maximum operating pressure. This information may be in the literature supplied to you by the company that installed your system, or you may have to ask the company or contractor directly.
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2
Find the expansion factor of your system by locating it on the expansion factor table. The expansion factor is the product of final and initial water temperatures of the water as it runs through your system.
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3
Multiply the expansion factor by the total system water content to obtain the expanded water volume.
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4
Determine the acceptance factor by using the acceptance factor chart. The acceptance factor is a product of the maximum and minimum operating pressures.
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5
Divide the expanded water volume by the acceptance factor. This will give the size of the tank your system requires, in gallons.
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Tips & Warnings
Reaffirm your determined tank size requirements with a specialist, or have one inspect your system and make a recommendation if the original contractor cannot be found.
