Bath tap hot water goes cold after 20 seconds

[Beaky]

POWERMAX 155 BOILER

We have hot water to all standard taps and shower, BUT, when we run a bath the hot water only lasts for about 20 seconds then runs cold, there is hot water in the system as the normal taps are OK, we found this was due to flow and if we turn the bath tap down to almost no flow, it then runs hot ! This is annoying as it takes so long to fill a bath and as we have 2 young children we need to use the bath. Ive had a corgi reg.heating firm in as it was also cutting out and theyve changed the mixer valve, sensors and stats etc and this has cured the cutting out problem, but we still have the problem with getting hot water throught the bath tap normally.
Any help would be greatly appreciated. Many thanks. Beaky

 

[a jeffries]

sounds like the blender valve has packed up, or if your in a hard water area scale will be the problem, both are easily fixed

 

[Beaky]

Many thanks,

The blender valve has been replaced but its still the same,how do I cure the hard water problem

 

[Agile]

Have you just moved in?

Was it alright before and stopped working?

I am wondering if you are expecting too much from your boiler.

Measure the maximum flow in litres per minute that you can get at a reasonable temperature into your bath and tell us.

Tony

 

[Beaky]

Hi Agile,

No we've been in for 5 years, it was a brand new house when we moved in , you could have bath tap on full and it would scald your hand if you touched it, over the past year it got worse and then eventually started cutting out aswell.
Cut out preoblem cured but the people who put in the new blender valve etc etc dont couldnt get the tap to run hot on normal output, hence we have to almost turn it off for it to give hot water.

Thanks for your reply, hope you can help further

Beaky

 

[Chris_4536]

Hi Beaky,

If the problem has got progressivlely worse over a period of time then it may well be scale causing it.

 

[a jeffries]

to find out if it is scale remove the top pipe on the blender valve and look inside the cylinder "coil" this should be clear and if it is scaled it will be very green and scale will be very visible