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Evening everyone so I’m just wanting to as a quick question please, how quickly would the pressure rise to over 3 if my expansion vessel is faulty been using the boiler but only a hour at night and at morning just now as it’s heating up the house with being mild ish outside normally over the hour or so it will go from 1.5 bar cold bring off 11 hours to 2.2 and stay there on Saturday it was chilly in afternoon so wasn’t right back down to the 1.5 pressure as I put it on a bit sooner and it raised to just over the 2.2 just a little and stayed there would I be correct in saying that’s probably fine as if vessel was faulty it would rise to over 3 bar within a hour or so of being on?
 
It depends on size of vessel compared with system water content and if vessel is maintained, so to be functioning properly.
1.5 bar cold raising to 2.2 bar hot is within acceptable limits.
But surely you should be having your expansion vessel checked and gas recharged (if found low) on your yearly boiler service?
 
I should say the boiler is only a year and a half old should the expansion vessel needs charged in that time? Service not due till March was going to get it checked then? Boiler been working fine I checked again tonight so 1.5 cold 2.2 when on for a hour n then reached room temp therm was set at, then about 40 mins later my wife was cold out in heating it’s been on for about an hour n a half went up to just a needle width over the 2.2 after about 45-50 mins n been sitting steady there for 40 mins after that so would I expect it continue to rise if it was faulty and faster than a needle width in 40 mins
 
I should say the boiler is only a year and a half old should the expansion vessel needs charged in that time? Service not due till March was going to get it checked then? Boiler been working fine I checked again tonight so 1.5 cold 2.2 when on for a hour n then reached room temp therm was set at, then about 40 mins later my wife was cold out in heating it’s been on for about an hour n a half went up to just a needle width over the 2.2 after about 45-50 mins n been sitting steady there for 40 mins after that so would I expect it continue to rise if it was faulty and faster than a needle width in 40 mins

Expansion vessels can lose a lot of their gas charge in one year.
Also possible a vessel has a fault, or faulty valve, same as you can have on a bike or car tyre.
If your boiler manufacturer allows it, then have your system cold pressure slightly lower than 1.5 bar, (- say 1.2 bar) if you wish to wait until next service.
If one of your radiators that you don’t depend on full heat from in winter, has some air in it, that would act as a temporary expansion for system
 
It doesn’t seem to be going any higher than the 2.2 and it’s been like that for last few weeks? I guess what I’m asking is do you think it would go way past that in a 2-3hr period if the vessel was faulty or needing pressure? When it reaches the 2.2 it’s sort of sitting there n the needle wobbles a bit which I’m assuming is normal but doesn’t really increase any more it stayed at that Saturday n then same tonight for at least an hour n never went up any farther ami worrying unessesarily
 
Also would you say 2.2 is high from 1.5? As far as I can remember it’s always went up by at least 0.6-7 bar?

The system will reach maximum pressure once the entire system water (pipe and rads) reaches maximum temperature it is set at on boiler stat. If stat is set a little higher, then the hotter water will expand more and pressure will rise a tad.
If that is below 3bar that boiler pressure relief valve is set at, then nothing will happen.
 
So does that mean it’s fine then my boiler for heating is set at 70 so Im assuming rads etc would reach that in 2hrs and hasn’t ever went above that tiny bit above the 2.2 so I’m assuming that’s fine? If it was to continue to rise to 3 clearly there would be an issue?
 
I’m sure the old boiler we had before this one the vessel wasn’t great neither was the boiler n whenthe vessel needed charged the pressure raised pretty fast to the 3 bar n blew out the valve like well within an hour
 
Think your worrying a bit to much the system will operate perfectly well at those range of pressures get it checked and serviced in March ok . Cheers kop
 
So does that mean it’s fine then my boiler for heating is set at 70 so Im assuming rads etc would reach that in 2hrs and hasn’t ever went above that tiny bit above the 2.2 so I’m assuming that’s fine? If it was to continue to rise to 3 clearly there would be an issue?

Yes, it looks like your system is working within limits, so no worries.
Systems typically do increase their pressure by a third maximum when hot.
But do as I say, drop the pressure slightly and get your service engineer to check and recharge the gas on the expansion vessel at next service
 

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