[thedoc (OP)]

Mike Malone asked the Naked Scientists:
   
Please read the following forum Q&A on a PONPC (point of no pressure change) I have on a heating system with a circulator and the expansion tank connected to it, assuming the temp is a steady 100F.

Can you explain how the tank can apply pressure without any movement on a closed system?

http://www.heatinghelp.com/forum-thread/147640/pumping-away-PONPC

Sincerely, Mike Malone

What do you think?

[CliffordK]

Most well tanks, and expansion tanks have a rubber bladder, and an air filled area around the bladder.  The air can be pressurized to assist with providing dynamic pressure to the system. 

Fill the system with water using a pump up to a certain pressure, and the pressure tank allows a portion of the pressure to drop as the tank is emptied.  With a solid steel tank, the pressure would drop too quickly, and any air in the tank would eventually be lost.

A one-way valve can aid with forward circulation of the water.

[Pmb]

Most well tanks, and expansion tanks have a rubber bladder, and an air filled area around the bladder.  The air can be pressurized to assist with providing dynamic pressure to the system. 

What is an expansion tank?

[Bored chemist]

http://en.wikipedia.org/wiki/Expansion_tank
Was that so difficult?

[JP]

http://en.wikipedia.org/wiki/Expansion_tank
Was that so difficult?

Between Wikipedia and lmgtfy.com, I don't think we need a TNS forum anymore.