Expansion tank

Wayco Wayne_2

Water increases it's volume 7% when heated from 70 F to 180 F. Without an expansion tank the extra volume would be seen as an increase in pressure in the system. An tank style expansion tank has an air bubble on on the top half of the tank. This air is squeezed when the volume increases and allows expansion of the water with out raising the pressure in the water. Sort of a hydronic shock absorber. A bladder tank has a diaphram across the middle that flexes and does the same thing. I hope this helps. WW

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Carl_11

Expansion Tank

Can anyone please help me understand what an expansion tank does? And does anyone know a good website or a suggested book that covers all the components for piping a boiler?

Thank you

lenny_4

check out amtrol

go to amtrols weg site its full of information. Most boiler manufacturers have a specific style they want there boilers piped you can check out any of there web sites to look at drawings or buy Dans book pumping away its full of great information.

Jed_2

Carl, try this

http://www.amtrol.com/pdf/extrolbroch.pdf

It will explain a lot

Jed

Big Ed

Let Me Try

A expansion tank is needed to help maintain a steady system pressure.

one step further.... The system pressure is needed to maintain a supply water to the highest point of the system.

One more point...We set the system pressure a few pounds higher then needed for a margin of safety. System water breaking into steam is a concern...

Steamhead

Try Dan's books

"How Come?" and "Pumping Away". Two of the best ever written on hydronics. Both cover the function of the tank, as well as how it fits into the system.

You can get your copies on the Books and More page of this site.