Showing 0 products
Frequently Asked Questions
Where does the pressure come from?
From height, and nothing else.
The cistern above the cylinder.
Its water level against the outlet.
That vertical distance is the pressure.
There is no other source.
Why is shower performance so variable?
Because it depends on the building.
A bathroom below the loft gets some head.
One on the same floor gets almost none.
It is geometry, not the cylinder.
Which is why pumped showers exist.
What does being open to atmosphere give?
Nowhere for pressure to build.
So no expansion vessel is needed.
No relief valves, no discharge pipe.
It is simple and forgiving.
And cheap to install and maintain.
Does it need a qualified installer?
Any competent plumber can work on it.
Without additional certification.
Which is not true of unvented.
In most markets that is regulated.
It is a real difference in ownership.
And the cistern - what does it cost?
Loft space, and its own problems.
It has to be supported and insulated.
It freezes if the loft is cold.
And it is open stored water.
With the maintenance that implies.
When is it simply not available?
In a flat, or with no roof space.
The cistern has to be above the cylinder.
By a useful height.
Without somewhere to put it.
The system cannot work at all.
Is there an advantage on a poor mains supply?
Yes, and it is often overlooked.
Hot water draws nothing from the mains.
The cistern refills slowly in the background.
And the stored volume does the work.
Unvented systems cannot do that.