Boiler firing up when toilet flushed

[eidolon]

Just had a full new central heating system installed plus a new bathroom suite and I've noticed that when you flush the toilet it causes the boiler to fire up for a few seconds.

What's that all about?

 

[eidolon]

Yes, lately it seems like my shower isn't as powerful as it was when I first had it fitted a few months ago but I wasn't sure if it was just my imagination

 

[eidolon]

Most common cause is a dead end with air in it, when you run the cold tap water goes back and forth through the boiler as the air expands. Two solutions find the dead end and remove it or one way valve before the boiler!

That makes sense. I've currently got my washer/dishwasher and downstairs toilet capped off while I get some more work done so that's probably the cause. Glad it's nothing serious.

 

[eidolon]

Fit a non return valve at the boiler, and dont forget the mini expansion vessel, otherwise you can pop the boiler seals. And we've seen this on a brand new boiler! Follow the manufacturers instructions.

Mick

I can't see anything like those. What would they look like? (boiler is a Baxi Eco Tec 40kw)