Recent: Safely remove screen protector from a Macbook Air?

Mend > Home Heating Systems

Mend Worcester 28i junior Boiler Pressure

How to increase pressure on Worcester Greenstar 28i junior boiler?

Just had a new combi boiler installed 2 weeks ago and it is running fine, but the pressure bar has dropped to within the red range i.e. too low. Plumber said to expect this but can't remember how he said to adjust it. There is a little white knob under the boiler that I think has something to do with it but there are also other knobs.... Does anyone know how to increase the pressure? The plumber is supposed to be getting back to me...... am I damaging anything by running the boiler on near zero pressure? Please help!

Liz H
January 2008
Thank you, Robert Lappin, I've hunted in vain for hours for those very instructions. None of the product sites or manuals have deigned to include such basic information for the plumbing-illiterate but I finally got it from your clear and concise explanation.

Blizzard
November 2018
Thanks Robert
That worked great and my heating system is back working.
Cheers tom

Tom
March 2016
Worcester combi boiler 28ijr.

After bleeding radiator(s), pressure can be lost, so to restore it to 1.5 bar do this.

Remove the plastic covering underneath the boiler by pushing it up and away from you. It will fall onto your hand. Look at it & you will find a plastic key fixed in position with three fixtures. Release the key carefully by pushing on the right side fixture & pull the key up towards you.

Go to the boiler & to the left of the pressure gauge & under, there is a tube that you insert the key into. There is a notch on the key so you may have to align this with the corresponding notch in the tube.

You do this by feeling & touching your way thru' this procedure. No need to lie on your back underneath the boiler (you'll just get wet & dirty).

Push the key up into the notch & again until you feel it tightening. Now turn it 90 degrees. There is a tap (white colour & is square) immediately to the left of the key insertion point. Turn this a bit away from you until you can hear water rushing in. Watch the gauge until it reads 1.5 and then turn the tap towards you (off).

Turn the key 90 degrees and pull it downwards to release this. Replace the key & the plastic cover and write this down somewhere.

Do this once a month & don't worry if the pressure is at 2.0. The 1.5 figure is optimum & 2.0 is not a disaster to worry about. :)

Robert Lappin
May 2015
Claude harper - you are a life saver..my boiler stopped working and as a girly girl who usually has daddy/husband (both away - typical) deal with everything - I had to have a go myself! First the thermostat started by making extreme loud screaming noises of which i thawt a rat was stuck in some pipework!! After realising I bled a radiator earlier and by the result of my boiler not working i bled the poor thing dry. Anyway long story short I turned the pin anti clockwise to 1.5 on the pressure clock (if thats wat you call it) and it worked!!!! My boiler working, im warm...who said we need men ey!!!!!!!!!!

Sabrina Bell
November 2009
There is a litte white valve on the underside of the boiler with a safety pin holding it in place remove the pin and turn the knob until you hear water being installed when the water pressure reaches the 1-1+1/2 bar then that is ample to run your boiler so turn the tap off and replace the pin

claude harper
October 2008

Related Questions ...

Mend boiler heating greenstar
1

Worcester greenstar 25si compact?

how to raise the pressure worcester greenstar25si boiler
Mend heating boiler pressure
1

How can I increase pressure in my Worcester boiler?

I bleed a radiator today which seems to have reduced the pressure to zero. How can I increase the pressure?
Mend boiler pressure radiators
1

over pressure?

I have a greenstar 24i boiler, pressure is normal, when I turn heating on pressure increases and eventually op... [Read more]
Mend boiler pressure heating
1

Worcester 28si boiler top up?

I have a very old worester 28si and the pressure is down to around 0.4 i cannot figure out how to up the press... [Read more]
Mend boiler radiators pressure
2

I only have heating downstairs... ?

Hi all. My heating has been a bit funny. The radiators upstairs aren't heating up at all and the ones downstai... [Read more]
Mend boiler heating pressure
1

how to reduce boiler pressure ?

i have set the bar pressure on my greenstar 37 cdi to high. how do I reduce it to proper level. Do I use the k... [Read more]
Mend boiler pressure blockage
2

Worcester 24i combination boiler pressure loss?

Had fan changed, PCB board changed, internal blockage due(manifold changed) water pressure sensor changed. N... [Read more]
Mend pressure worcester heat
1

Faulty Worscester 35 CDi loosing pressure?

My Worcester 35cdi has had 4 replacement heat exchanger's in less than 10 years the first 2 were within the fi... [Read more]
Mend combi boiler pressure air lock
2

How can I stop my Worcester 24i from building up too much pressure ?

My Worcester 24i combi boiler has just started to build up pressure beyond the blow off valve setting (IE. in ... [Read more]
Mend boiler heating radiators
1

How do I raise the pressure on my boiler after bleeding radiators?

How do I raise the pressure on my worcester heatslave 20- 25 oil boiler after I have bled the radiators
Mend boiler heating thermostat
1

combi oil Worcester greenstar heatslave 12/18 switches off?

I have a internal combi oil Worcester greenstar heatslave 12/18 Its has a built programmer and Hot water t... [Read more]
Mend boiler heating power
1

No power getting to Greenstar Highflow boiler?

pressure dropped so refilled, now no power at all getting to boiler?
Mend combi boiler pressure pilot
1

Worcester combi boiler has lost pressure after bleeding radiators?

I bled radiators now digital pilot light off and pressure gauge on zero. Help please!
Mend boiler heating worcester
1

How do I release the pressure on my greenstar 25Si/30Si boiler?

The pressure on my boiler is low which means I cannot get hot water. I have read through the instructions and ... [Read more]
Mend boiler worcester greenstar
2

how do i fix my worcester boiler?

my Worcester greenstar si junior boiler has always needed the water pressure topping up time to time since ins... [Read more]

How to mend ...

Find out how to mend just about anything howtomendit.com for free repair help, information and advice.
Mend Home Heating Systems ...