how to I lower the pressure on the boiler?

i have let the water out of the system from the drain valve but the pressure drops and when i put the boiler back on it goes back to 3.5

thomps at 43
March 2009

You should have drain plug on the ground floor radiator. Best one to choose is in the bathroom/toilet or any room which has no carpets. Kitchen may be also considered. Radiator nearest to bolier if possible.
switch off central heating and do the following when it has cooled down (after 15 mins)
Connect any suitable plastic pipe or use a shallow containor which can slide under the draincock. Slowly open bolt in the draincock slowly at first so that all the water does not rush out. Be patient. drain the waterkeeping one eye on the gauge on the boiler. Be careful or you might get burnt with hot water. It is a long way but it works. Be careful you will need to drain about quarter bucket full. Keep an eye on the gauge and when the needle reaches at 1.5 or below tighten the valve screw.
I hope above helps.
OR
You have air release valve on top of radiator to release air trapped in the radiator. Choose the radiator nearest to boiler.You can open that which will release water. You will get there in the end. May take you half an hour with this method.
Please make sure this year in summer you replace the additive in the central heating water, it is not wise to use plain water otherwise corrosion will occur in your central heating leading to bigger problem. Get free advise from plumber merchant or nearest B & Q stores or check on the web.

koter002
March 2009

let some out the drain off tap or via a vent bleed in the rad then represurize do not use the safety valve on the boiler as they can stick slightly open

ajm heat
March 2009