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