boiler comes on for a couple of sec after i turn the cold tap off

[arman123]

ok just changed the taps on my bath ive put on mixer taps fitted them no problem but know got another problem ive got a vaillant turbomax boiler and when i turn the cold tap on and soon as i turn it off the boiler fires up for a about 2 sec even when the washing machine takes water same thing my washing machine is cold water only was searching online and came across wat is called a dead leg but have not got any lenth of pipe that is not in use any idea people wat could be causing it thanks

 

[newbie1]

i have a dead leg if i sit on the loo too long

 

[arman123]

ha ha ha

 

[newbie1]

seriously couple of options
non return valve on cold supply to boiler as a cheap option
check with installer to make sure no dead legs ie length of unused pipe thats just been capped off rather than taken back to where it tees of from

 

[arman123]

i fitted the taps myself and no extra pipe that has been left or cut off and the non return valve got one already on the boiler main water pipe if i turn the water supply off to the boiler the problem is gone

 

[peteh20]

have simular problem but normally on oil combi's. Its the presure forcing the flow switch to activate the boiler when you turn the cold tap off. Check your water presures are within the manufactors recommendations if not fit a presure reducing vavle or a shock arrester