Lowering pressure on Worcester 30si combi

[fungit]

After bleeding all of the radiators in the house, I discovered that the pressure had gone very low on the boiler (Worcester 30si). I knew how to increase the pressure, having found some advice on this site a few months ago. I opened the tap with the plastic key underneath the boiler and turned the square plastic nut until the water pressure began to rise.

Unfortunately, I didn't close the nut in time and the pressure went up to around 3 bars. Now I can't get the pressure to come back down! I've tried bleeding one of the radiators - I must have taken several litres out of it but, if anything, the pressure's increased! There is water trickling out of the overflow outside but it's been hours now and it's obviously not solving the problem.

Is there another way to release some pressure? Is there a particular trick to lowering the pressure by bleeding radiators? Should the heating be on/off? Should the other radiators be open/closed? Should I choose a particular radiator? Please help!

 

[swbjackson]

Have you shut off the filling link and removed the key? If the boiler is on the pressure will rise slightly.

There should be a drain off at a low point on the system. Attach a hose to this and drain off a small amount of water at a time until the pressure is back to normal.

Mike

 

[fungit]

Have you shut off the filling link and removed the key? If the boiler is on the pressure will rise slightly.

There should be a drain off at a low point on the system. Attach a hose to this and drain off a small amount of water at a time until the pressure is back to normal.

Mike

Yes, I've closed the link. I don't know if there's a drain off point and I don't want to start unscrewing things without knowing what the are. Does anybody know this system's fittings?

I can't help thinking that, if there's a simple way to increase the pressure, there should be a simple way to decrease it too.

 

[ianshearer]

I have been in this position before myself, I had turned the fill valve full on, instead of full off ( It only hisses when it is partially open, full open it is silent, and I thought I had it in the off position.
The over pressure valve then opened at 3 bar, so the pressure never drops below 3 , even when a lot of water is bled out a radiator.

Having said that, a suprising amount has to come out a system to get the pressure back down. It can take 10 minutes or so via a bleed valve, best if you can find the drain cock, if there is one

 

[fungit]

I've now left the heating off all night and the pressure's not going down at all. The overflow has been pouring all night too - I thought the overflow was supposed to release pressure - how can the pressure not have gone down?

Also, I decided to close off all of the radiators and try to drain the whole system into pots but one of my radiators starts leaking from the tap when you try to close it - is this because of the pressure?

Help me! Please! We're freezing here!

Or, should I just turn the heating back on? What damage might I do?

 

[ianshearer]

If the overflow has been running all night, you have NOT switched off the filling loop properly.
You have done what I did, and turned the filling loop taps full on instead of off.

Find the tap which is on the mains water side of the filing loop, probably the narrow half inch pipe. Put it in the other position, and the water should stop coming out the overflow.


Then open up all the radiators and bleed water out of whichever one is most convienient untill the pressure drops. It will take a while.

phone me on 07969 274 365 if you like

 

[clf-gas]

The blind leading the blind

Next too the key you will see a white square knob, this you know as you used it to overpressurise your boiler. Next too that you will see a black knob, this is the drain point. Place a bucket or bowl below this and open slowly, drain off water until needle is just above one.

Make sure both valves are closed and remove the filling key and place it back in the grips of the under panel.

 

[fungit]

The blind leading the blind

Next too the key you will see a white square knob, this you know as you used it to overpressurise your boiler. Next too that you will see a black knob, this is the drain point. Place a bucket or bowl below this and open slowly, drain off water until needle is just above one.

Make sure both valves are closed and remove the filling key and place it back in the grips of the under panel.

Is the drain point to the other side of the key from the white square knob? (Is the key between the white square knob and the black drain point knob?) I've had that open now for about an hour and have emptied several litres of water through it but the needle hasn't gone down at all. Am I doing something wrong? Is there something else I have to do? Should the radiators be open/closed? Should the heating be on/off? Should I turn on/off the taps? Do I need to drain radiators too?

 

[ianshearer]

Has the overflowing water stopped?
That has happen first. If it is still overflowing, it means the filing loop is still letting water in.

If it is still overflowing, try the filling knob at both extreme positions, and give it a minute to have an effect

Once the overflowing has stoped, you can drain water out from the drain knob, or a bleed valve on a radiator, quite possibly a couple of litres to get it down to 1 bar

Is there something else I have to do? No
Should the radiators be open/closed? open
Should the heating be on/off? doesn't make any difference,, but put it on if you are freezing, the overpressure valve will just overlfow a bit to keep it at 3 bar as it heats up
Should I turn on/off the taps? no
Do I need to drain radiators too? no, its all the one pressurised system

 

[clf-gas]

Has the overflowing water stopped?
That has happen first. If it is still overflowing, it means the filing loop is still letting water in.

If it is still overflowing, try the filling knob at both extreme positions, and give it a minute to have an effect

Once the overflowing has stoped, you can drain water out from the drain knob, or a bleed valve on a radiator, quite possibly a couple of litres to get it down to 1 bar

Is there something else I have to do? No
Should the radiators be open/closed? open
Should the heating be on/off? doesn't make any difference,, but put it on if you are freezing, the overpressure valve will just overlfow a bit to keep it at 3 bar as it heats up
Should I turn on/off the taps? no
Do I need to drain radiators too? no, its all the one pressurised system

Passing|| with the key removed

Tell fungit about the plate to plate now

 

[fungit]

Has the overflowing water stopped?
That has happen first. If it is still overflowing, it means the filing loop is still letting water in.

If it is still overflowing, try the filling knob at both extreme positions, and give it a minute to have an effect

Once the overflowing has stoped, you can drain water out from the drain knob, or a bleed valve on a radiator, quite possibly a couple of litres to get it down to 1 bar

Is there something else I have to do? No
Should the radiators be open/closed? open
Should the heating be on/off? doesn't make any difference,, but put it on if you are freezing, the overpressure valve will just overlfow a bit to keep it at 3 bar as it heats up
Should I turn on/off the taps? no
Do I need to drain radiators too? no, its all the one pressurised system

Passing|| with the key removed

Tell fungit about the plate to plate now

The overflow outside is still running but it has been all night (almost 24 hours now). So I'm not holding my breath for that to stop. The white square tap is completely shut.

I have now bled many litres from the radiator and from the drain point beneath the boiler; I honestly can't see any change in the pressure, so I'm beginning to think that it won't happen. Is something else going on? Is there any chance I'm still introducing water to the system?

 

[swbjackson]

Is the filling link out of the boiler? Unless it is you don't know that the valve is shut. If it is and the pressure keeps rising it sounds like the plate heat exchanger may have failed.

Mike

 

[clf-gas]

OK follow this.


Turn the valves far left and far right, this issolates the rads.
Now drain bolier as I posted earlier. Whilst doing this tap guage lightly to make sure needle is moving. close drain point.

leave for next 30 mins, the guage should not move. if it does then your plate to plate Heat exchange is holed and passing to your rads.
This is the cuase of over flow.

 

[fungit]

Oops. I just took the edge of a screwdriver and managed another quarter-turn of the white square knob. Funnily enough, the drain point stopped draining within a couple of seconds. I was totally convinced that it was totally shut. What a muppet. If I'd taken your advice last night and checked it again I could have saved a lot of time and trouble.

Thanks for all of your time and advice. Very much appreciated. Have a happy New Year.

 

[clf-gas]

Must of been the strong northern accent,

With the key removed

Still never mind.

Happy new year