Sealed System Pressures, (hot & cold)

[AndyT68]

In a sealed system, should there be any pressure difference between system running (hot) and system off (cold)?

My system heated by an ideal classic ff250, operates hot at 2 bar. But whenever the system shuts down the pressure drops down to 1 bar within about 1 hour. Is this normal?

 

[Gas1976]

When you heat water it expands

 

[AndyT68]

I thought the pressure vessel was there to take up any expansion/contraction whilst maintaining pressure?

 

[Gas1976]

The expansion vessel is there to allow for expansion but the system pressure will rise when hot and fall when cool

 

[AndyT68]

But is a 1 bar drop for an average sized system par for the course?

 

[MJN]

Yes, although it makes more sense to put it the other way around i.e. a 1 bar rise when hot is par for the course.

Mathew

 

[xr4x4]

Without the pressure vessel the pressure would rise even higher when hot.