increased hot water pressure

[nellymcl]

Hi all
When my hot water is heating the is a large increase in the hot water pressure. When you open the HW tap the water shoots out the settles down.

This is a sealed system ( I think that's what it's called) with a hot water tank.

Any thoughts?

Thanks

 

[muggles]

What make of hot water cylinder is it? Can you post a picture? Is this a new problem?

 

[nellymcl]

Hi Sorry it took so long to reply. This increase in pressure also happens when it is just the heating that is on. It appears there is cold water getting into the hot water as when I turn on the tap it comes through only warm for a few seconds. As you can see it's a mega flow system.

Thanks

 

[mcmoby69]

when did you last have the boiler or the cylinder serviced?

 

[nellymcl]

The boiler was serviced in November. Never had the cylinder serviced although it has been drained down before.

 

[muggles]

Is your initial hot water pressure the same as your cold, greater, or less?

Unvented cylinders should be serviced annually, to check the safety devices are operating correctly and to maintain the 25 year warranty

 

[nellymcl]

Thanks. I would say my cold water pressure is more than the hot.

I didn't know there was a 25 year warranty on the cylinder or that it needed serviced. I will look into that now though.

 

[Agile]

You would want to know that!

It should have a Benchmark Certificate often on the side which should have been filled in by the installer!

What I think is happening is that the supply to the property is somewhat limited and the air bubble in the cylinder is acting like an accumulator and giving an initial higher pressure until that reserve is depleted.

It can also be caused by partial blockage in the cylinder inlet filter.

But many would like that extra pressure!

Tony