hi i have a vokera linear 24 combi boiler which was already fitted when i moved here.when you turned on the hot water tap everthing seemed ok hot water but like most combi's i think not great pressure.now the pressure is high but if i turn the tap on full water runs hot and then cold' if i turn down the tap water will stay red hot.

monty45, September 2008

Hi I have a worcester 24i junior boiler which recently had an air pressure switch changed on it. When the engineer put my boiler back together it was working fine now it has stopped again and another engineer has mentioned it could be the venturi? Can some one shed some light on what and where a venturi is please?

Francis, April 2009

I had the same problem with my vokera excell turned out to be the flue venturi, water running hot then cold before the boiler fired up again

thbetws, October 2008

thanks for that info mohammad,i'll check that and change it if required. theres a good local place for all bits so getting part should be oki'll let u know the out come on here

monty 45, September 2008

it may be a bit more simpler then that if you open up the boiler you will have a copper pipe running up the right hand side into the heat exchanger it is held in by a nut if you undo this you willl find a small plastic ristrictor this is probbably knackered its like a washer it regulates the amount of water going through the boiler about 2/3 quid max as soon as you take it out you will be able to see if its the problem or not...

mohammed, September 2008

thanks for that C think i'll just get someone out to look at it when i have the funds,at least it still works at the minute.

monty45, September 2008

The flue venturi on these boilers need to be completely clean for reliable differential air pressure switch operation operation. It normally becomes evident first when running baths or showers as hot water cycling. Download the manual, read the schematics and check that the differential air pressure switch is not dropping out when the fan is on (obviously it should remain on when the fan is going full tilt if things are OK). You need to be competent to do this with a multimeter, there are mains voltages around. If the switch is dropping out then health and safety regs require that a Corgi man open the combustion chamber and clean the venturi/checks the flues etc, though it is not a difficult job.

c, September 2008

thanks gas man but this did not happen when i first moved in to house. you turned on hot tap to full on bath and it stayed hot but average pressure. now high pressure and hot /cold water but when cold, boiler goes off.as i say was not like this a year ago so somthing has happend

monty45, September 2008

Thats how most combis work.The less water that goes through them the hotter it is.

Gasman, September 2008