Apologies as I know it's been asked before

[Riley]

As per the title

I have an interesting scenario where a boiler fires up briefly every time a toilet in a property is flushed I have tried non return valves on the two toilets as well as a shock arrestor on the mains as it comes in and also on the way to the boiler

None of these have fixed the problem does anybody have any little gems that I might try

Boiler is a flexicom so as far as I'm aware there is no option to affect how the flow is picked up

 

[ShaunCorbs]

have you tried a nrv/shock arr by the boiler?

 

[Riley]

To be clear Shaun do you mean on the cold inlet into the boiler if so then yes I have tried both

 

[Scott_D]

Dead leg full of air on hot or cold pipe?

 

[ShaunCorbs]

To be clear Shaun do you mean on the cold inlet into the boiler if so then yes I have tried both

yes i would say any air in the pipe?

 

[Riley]

If there is I have no idea where it is as I repiped most of the house apart from the kitchen but boiler worked prior to that

 

[ShaunCorbs]

If there is I have no idea where it is as I repiped most of the house apart from the kitchen but boiler worked prior to that

anything changed from then and ball valves ok? and does a cold tap do the same

 

[Riley]

Seems to only be the toilets mate but will double check tomorrow. I was thinking dead legs but it must have been pre-existing if it was

 

[ShaunCorbs]

Seems to only be the toilets mate but will double check tomorrow. I was thinking dead legs but it must have been pre-existing if it was

are the toilets close together ? and whats the pressure over 3 bar?

 

[Riley]

Opposite sides of the house mate one upstairs one downstairs

 

[ShaunCorbs]

Opposite sides of the housemate one upstairs one downstairs

that is weird could understand if close, any water hammer noise?

 

[Riley]

None at all mate.

To bring you up to speed
New internal mains to boiler and outlets
New bathroom that didn't exist before
New shower room downstairs replacing old bathroom.
All outlets still in use no dead legs to my knowledge

 

[ShaunCorbs]

when does the boiler fire when the bogs are filling or just as the valve shuts off from filling?

 

[jonnyswamp]

Are there nrv's on the new shower feeds?
assuming there is a new shower fitted in new bathroom

 

[Riley]

Toilets and apparently the washing machine

 

[Riley]

Are there nrv's on the new shower feeds?
assuming there is a new shower fitted in new bathroom

One is a bath shower mixer - no nrvs
One is a thermostatic shower bar yes NRVs

Both showers have been tested however and no boiler issue

 

[thompsonbrown]

Seems strange that boiler fires up just when these toilets are flushed and not effected by opening a cold mains tap etc.. I would check mains cold is fully opened and have decent pressure for boiler, If all else fails why not restrict mains flow to wc's. Fit inline restrictors or crack down ball-a-fix valves.

 

[Riley]

Mains fully open. Definitely no taps cause this issue its very weird

 

[ShaunCorbs]

Are the ball balves decent ones not the cheap plastic crud that gets supplied normally ? If yes I would change them for a decent one and see if that helps

 

[Riley]

All brand new fluidmaster fillers mate

 

[jtsplumbing]

May have over sensitive flow switch or faulty one in boiler !

 

[Riley]

May have over sensitive flow switch or faulty one in boiler !

The thought had crossed my mind mate but I would've thought all outlets would've set it off ???? Not just the toilets and the washing machine Would you agree ???

 

[ShaunCorbs]

All brand new fluidmaster fillers mate

May have over sensitive flow switch or faulty one in boiler !

+1 you could try and put an unvented vessel (as a test) on the mcws to the boiler and if that stops it change the flow switch

 

[jtsplumbing]

The thought had crossed my mind mate but I would've thought all outlets would've set it off ???? Not just the toilets and the washing machine Would you agree ???

Strange things happen in the world of plumbing !!!