Hot and cold bath tap

[Molliealyssa]

our boiler pressure is dropping to 0 even after having the blender valve replaced, paid £80. Maybe 2weeks ago. This was when our pressure was at 0 and only cold water was coming out. Now my water is going hot and cold every 15/20 seconds from the bath tap. Any ideas only moved in a month ago

 

[terryplumb]

Boiler pressure dropping to zero is due to loss of water from the sealed system,and can be from a leak or a problem within the boiler, (expansion vessel or heat exchanger issues).
What boiler do you have ,and what is its status when bath hot tap is running ? Do other hot taps suffer from the same problem ?

 

[Molliealyssa]

We have a baxi duo tech combi 28 - all taps are going hot and cold and pressure is still on0

 

[Deleted member 267285]

Your issue hasn’t been resolved then. Not heard of a blender valve on a combi boiler, perhaps the diverter?

 

[terryplumb]

If you top up pressure to 1 bar ,how long does it take pressure to drop to zero ?
The hot/ cold from taps can be due to a number of issues. You need an engineer to visit.

 

[Molliealyssa]

Sorry it was the diaphragm on the diverter he believed it to be originally however when he looked it wasn’t this it was a different part he said was causing the issue.

 

[Molliealyssa]

If you top up pressure to 1 bar ,how long does it take pressure to drop to zero ?
The hot/ cold from taps can be due to a number of issues. You need an engineer to visit.

We can’t get it to go up even using the taps under the boiler itself like my grandad showed me last time.

 

[terryplumb]

Did the person who worked on the boiler not successfully top up the pressure ??
Show us a pic of the pipework and valves under the boiler ,particularly what you are using to try to top up boiler pressure.

 

[Molliealyssa]

It’s been working fine since the issue but only for two weeks

 

[dilalio]

Can you hear water rushing in to the boiler when you open the filling loop?

 

[Deleted member 267285]

Once the pressure has been fixed, if the issue persists, it might be worth having the Hall effect sensor checked