boiler starting up when cold taps on or toilet flushes

[bananaboy]

Plumber just repaired a leak on the cold water feed to the boiler but now boiler starts up when any cold tape turned on or toilet is flushed. Any ideas?? Thanks

 

[powell30]

He must have connected hot to cold somewhere......

 

[diverdee]

does it just fire very briefly when u close or open a tap if so u have air in the hot pipe somewhere trying to compress and when u release the pressure through a cold tap it decompresses

 

[bananaboy]

fires up in the same way as if a hot tap was turned on and off

 

[diverdee]

yep sounds like he got em crossed

 

[seco services]

fires up in the same way as if a hot tap was turned on and off

so its only firing for a few seconds.

 

[bananaboy]

if a hot tap is turned on then off, the boiler fires up and stays running for approx. a minute after the hot tap is closed. It's acting the same way when cold taps are turned on or toilet flushed

 

[seco services]

has he altered any pipework etc as you say this only started after he fixed the leak, but we all know just fixing a leak won't cause the boiler to fire up.

you can fit a check valve on the hot pipe out of the boiler useally solves it.

 

[giblets]

Sounds very much to me as if there is a long and capped unused deadleg somewhere in the system that is now full of air after the plumber drained down to repair the leak. The air in the pipe is acting like a shock absorber and fooling the boiler into thinking that there is a hot water demand when a cold tap is turned on/toilet flushed. This is one of the reasons that ALL unused pipework should be removed as far as possible back to a pipe that remains in use. If you originally had tanks in the roof has the cold main up into the roof been disconnected?

 

[Deleted member 105431]

check/non return valve on dhw outlet of boiler will prevent nuisance operation of boiler due to dead legs while still allowing expansion back down the cold main.

 

[andytheplumber]

I might be way out here.
But if the shower mixer valve has gone . When you open a cold tap it draws the hot water through the shower valve. This in turn fires up the boiler. It might just be a fluke that its started since you have had some work carried out . It might be worth checking out

 

[seco services]

I might be way out here.
But if the shower mixer valve has gone . When you open a cold tap it draws the hot water through the shower valve. This in turn fires up the boiler. It might just be a fluke that its started since you have had some work carried out . It might be worth checking out

what the f*k.
how does the toilet filling pull the cold water from the shower valve which pulls the hot water to fire up the boiler ?

 

[andytheplumber]

Have a think.