I'm in a new flat with a combi boiler (glow worm) an two bathrooms. There is a strange thing going on with water, like there is an overflow/access which makes a toilet in one of the nathroom flush itself. kind of.
This happens when water is used in the othe bathroom or in the kitchen (though may not be every time, I haven't observed long enough) - so the water flshes down then stops (thankully - so it's not leaking all the time in that toilet).
When the showe is used in the same bathroom as that toilet, it only 'flushes; afetr the use of shower, I think, not durng - hence the shower pressure is better than in the other bathroom, that's weak as the toliet leaks all the while shower is open there.
When you just flush the toilet, it's fine if a bit slow to fill. The toilet in the other bathroom has no suck spontaneous flushing issue.
I wonder if this is a boiler imbalance of some sort or a valve faulty somewhere? The boiler has not ben services bu previous owners for a few years.
Thank you for reading!