Low pressure water only in bath

  flycatcher1 22:38 05 Jun 2014

A friend has had a combi system fitted in his bungalow since then the water pressure is the bath is very low. All other taps over wash basins and the sink are fine. The problem has only happened post combi. His plumber says that nothing can be done - I doubt this and would appreciate any ideas on the subject.

  [DELETED] 22:44 05 Jun 2014

Combi boilers heat the water as it flows. Bath 'taps' have a large outlet comparable to 'sink' taps. The water flow is regulated via the boiler on how it heats the water.

  Forum Editor 22:53 05 Jun 2014

It's important to recognise the difference between pressure and flow rate. Cold water will be delivered to the bath directly from the mains, so unless there is an intermediate pressure reducing valve the pressure will that of the mains supply. The flow rate will be governed by the supply pipe diameter.

Hot water will of course be delivered via the Combi boiler, so flow rate will be reduced as the water has to pass through a plate heat exchanger.

  bumpkin 23:11 05 Jun 2014

With a combi the pressure to all taps will be the same. The flow however may appear to be slower from a larger tap. This is normal.

  flycatcher1 23:16 05 Jun 2014

Thanks for the prompt replies. The flow of hot water is only slow over the bath, the washbasin in the bathroom is OK. He says that it takes "for ever" to run enough hot water to have a bath.

For one reason and another I have been elected to sort this problem out and I need some background before I employ a plumber of my own choosing.

  bumpkin 23:27 05 Jun 2014

The flow rate from the hot and cold should be about same (without the technicalities) If the flow from the hot is as little as you say then it could be obstructed by something in the pipework or tap.

  bumpkin 23:32 05 Jun 2014

It is an easy thing to test, turn on the cold only and see how long it takes to fill for example a 5ltr container, repeat with the hot water. If there is a big difference then you have a problem.

  [DELETED] 23:32 05 Jun 2014

flycatcher1, it is up to the boiler to regulate the flow of water to the bath or any other receptacle to a legally set temperature. It is doing its job. If your friend requires a better system then that is ok.

  bumpkin 23:50 05 Jun 2014

rdave, sorry to disagree with you on this occasion but there is no legally set temperature.

  spuds 00:03 06 Jun 2014

I recently had a combi boiler fitted, as some of you may recall. Since then Worcester Bosch have sent an engineer to do a 'performance test' on the boiler. Worcester Bosch set their boiler regulated temperature at 50 degrees.

The W/B engineer suggested that any problems with hot water flow or temperature, a 2 minute open tap free run of water should locate any issues, because by that time the system should have stabalised itself?.

Not sure if that's the answer you are seeking!.

  [DELETED] 00:23 06 Jun 2014

bumpkin then that's fair enough. Thought there was a new regulation for bath/shower water supply to stop scalding?

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