Boiler firing up causes tap to drip!

[Vicario]

Here's a mystery. Every morning at 6 the boiler (Baxi condensing one with hot water storage cylinder etc.) fires up and the kitchen tap starts to drip. As it's a mixer it's hard to know if it's the hot or cold side, but I suspect the hot. The drip is quite bad for a while but eventually stops and is then fine for the rest of the day. Not really a problem but I'm intrigued to know what might cause this.

 

[1983]

Hi, what type of hot water cylinder do you have, ie is it standard open vent with tanks in attic or is it a pressurised one?

 

[Vicario]

Tank in the loft.

 

[Vicario]

It's an Astracast Targa monobloc tap. If I wanted to change the washer, is that easy?

 

[Armo74]

I believe that tap is a 1/4 turn tap which will require a ceramic disc cartridge and not a washer.

How easy the job is will depend on how easily you can isolate the water supply and how easily you can get the old one out.

 

[HERTS P&D]

Normally cheaper to change the tap.

Andy

 

[Vicario]

Thanks for all the advice. I've noticed that if I swivel the spout by 90 degrees (away from the sink and back towards the wall) the drip stops.
Is that normal? Anyway, I think I'll go for a new mixer.

 

[petertheplumber12]

I think you have a flow pipe from the boiler in close proximity to the hot water pipe to the tap. When the boiler starts to heat the cylinder with hot water the other pipe with cool water in it starts to warm up and the water in the hot water pipe expands enough to push past the washer/ceramic insert, etc. then once temperature is established it stops.

There may be other reasons but that was my first thought. Ceramic taps are best used on sealed systems, the water in the tank is not clean enough and can scratch the face on the hot water side of the tap or cold water side if coming from the tank, like upstairs. You can get quarter turn washer taps.