Greenstar Highflow 440

[paj66]

Hi all - I have had this boiler fitted for over 3 years now and it has worked perfectly.

I tend to keep an eye on the pressure gauge because I have been removing and replacing radiators whilst decorating and it's become a habit!

I've not taken any radiators off lately, and the system is air free, however......

The pressure consistently drops down to about 1.5 bar and needs topping up every four or five days. There appears to be no sign of leakage from any radiators or the boiler itself and I'm at a loss as to what the problem might be - any ideas please?

 

[petit_pablo]

Drops down to 1.5bar from what?

Check outside there should be a discharge pipe from boiler. See if this is dripping

 

[paj66]

Maybe it's not bar - the gauge reads from 0 to 4 - I normally top up till it's about 2.5.

Checked outside - no signs of dripping and no water stains etc on the ground suggesting that it has been.

 

[Agile]

You should not top up above 1.5 bar cold.

It should not rise above 2.0 bar when the rads are hot.

Tony

 

[paj66]

OK maybe my ignorance is more fundamental than I thought! As I understood it, the red needle on the pressure gauge shows the lowest water pressure allowable - is that not correct? Might be worth mentioning that the system has operated perfectly even with these "problems" I'm having!

 

[Agile]

What I told you is correct!

Red lines usually mark a NOT allowed senario.

Perhaps you always park your car on red lines?

Tony

 

[paj66]

Tony

No need to bite my head off mate - just looking for an explaination as to why it keeps losing the pressure - any thoughts on that?

 

[Agile]

If you set it correctly then it may not lose pressure.

Tony

 

[gas4you]

I always leave any adjustable red marker line at the point to fill to for the customer, about 1.2 Bar.

If you are filling to 2.5 then this will be your problem. However, there is a slight chance that by the prv opening to release the excess pressure when the system is hot, you may now have a bit of grit/muck on the seat of the valve, stopping it shutting properly.

 

[paj66]

OK Tony, Dave thanks a lot - think I'm beginning to understand now Do all systems work to the same pressure settings? (1.5 - 2 bar). Does the sytem pressure drop when there is no demand being placed upon it?

 

[gas4you]

As a general rule all domestic systems are pressurised to about 1.2 Bar ish when cold.

As the system heats up the pressure (assuming the pressure vessel is of adequate size for the system) will increase to approx 2 Bar, then as it cools will drop back to the cold pressure.

The expansion vessel on the boiler/system is there to take up the expansion or the system water as it gets hot.

In a traditional open vent system, the feed and expansion tank takes care of this and when the system is hot, the water level in the F & E tank will rise approx 1-2".

 

[paj66]

Magic - thanks for that. So, to summarise, I've been overfilling the system each time I put a radiator back on and have then got worried when the system self regulates itself back to the correct pressure and then overfilled it again - is that about right? All I need now is a dunce cap and a corner to stand in

 

[gas4you]

In basic terms, yes, you've got it