Water Heater Expansion Tank

What is an expansion tank and what is the purpose of it?

A water heater expansion tank or expansion vessel is a small tank used in closed water heating systems and domestic hot water systems to absorb excess water pressure, which can be caused by thermal expansion as water is heated, or by water hammer.

The vessel itself is a small container divided in two by a rubber diaphragm. One side is connected to the pipe work of the heating system and therefore contains water.

The other, the dry side, contains air under pressure, and normally a car-tire type valve for checking pressures and adding air.

When the heating system is empty or at the low end of the normal range of working pressure, the diaphragm will be pushed against the water inlet.

As the water pressure increases, so the diaphragm moves compressing the air on its other side.

The compressibility of the air cushions the pressure shock, and relieves pressure in the system that could otherwise damage the plumbing system.

When water heater expansion tank is used in domestic hot water systems, the tank and the diaphragm must conform to drinking water regulations and must be capable of accommodating the required volume of water.

In the past, domestic plumbing systems often contained more air than they do currently. Thus, expansion tanks are now used more frequently than in the past.

What is the price for a water heater expansion tank?

The cost will vary drastically according to the brand that you want to buy but the average price can be between $35 and $60 dollars, this is only for the tank itself. However, if you don’t know how to install it, you might need a professional to do that for you.

Usually the price to have an expansion tank installed including the labor and part is around $300.

For those who want a step by step instruction in how to install an expansion tank, I will be providing detailed information in the next page, please, Click Here.

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