Bathroom hot tap hammering with slow flow

[Paule1882]

Hi, just moved in and the hot tap in our En suite basin hammers and slows almost to a stop when turned on, a plumber friend suggested it was the cartridge in the tap so I replaced the (mixer) tap, still the same. If you open the tap slowly and only half way you can get a bit of a flow. We have a combi oil boiler and all the other hot taps in the house are fine with good pressure. I wondered if anyone out ther had come accross something similar?
Thanks in advance, Paul.

 

[Wayners]

Sounds like a tap problem.
Did you replace tap?

 

[denso13]

Does sound like a tap problem, odd if you have changed it though. Does it help if you run another hot tap and basin at the same time?

 

[Paule1882]

Hi, Yes I've replaced the tap, but as denso13 suggested, if I open the bathroom hot tap the flow is improved in the problem En suite??
I have tried a wet vac in case it was air but with no improvement.

 

[CountryFan]

Is there an isolation valve for it?

 

[Paule1882]

No, no isolation valve.

 

[denso13]

Restriction in the pipe possibly, something is causing the low flow. Any way to check the flow from the pipe before the tap? Might need to disconnect and reconnect.

 

[Paule1882]

Yes, I’ll try that tomorrow as it’s all inside a wall unit but easy to get to the tail connectors then. By the way it’s all been plumbed in 15mm plastic pipe.

 

[CountryFan]

Yes, I’ll try that tomorrow as it’s all inside a wall unit but easy to get to the tail connectors then. By the way it’s all been plumbed in 15mm plastic pipe.

So will have reduced it down to approx 13mm with the insert, still shouldn't affect it though as flexi's are reduced sometimes too and they don't do the same.

 

[Paule1882]

Yes, all the other taps are the same and they’re all fine with a really healthy flow.