Hot water tap gives only warm water (combi boiler)

9 Dec 2014
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United Kingdom
Our problem is that the bath and shower doesn't put out very hot water, especially in cold weather.

We have a Baxi Combi 30 HE boiler.

There is a control tap that seems to control the cold water going into the boiler, if I turn this tap off then no water flows to the sinks (either hot or cold tap). If I open it fully, then the hot taps give only lukewarm water.

I have found that if I open this control tap to a very minimal position, where the water pressure must be quite low, then I an get acceptable hot water from the taps. However, if I then flush the toilet and run a sink tap at the same time, I sometimes get a chugging sound from the pipes as it has negative flow or cant get enough water.

If I then open this control tap a bit more, then the hot water tap gives a lower temperature and I can only get acceptable hot water by running the cold sink tap at the same time.

This problem is happening especially in winter, but even in autumn/spring - we have very hot baths so it is noticeable.

Also the cold water taps in the sinks often give out warm or even hot water, e.g. run some hot water in the bathroom then go to ensuite and run the cold tap and hot water comes out for a while.

Is this something that can be fixed with settings on the boiler or adjusting that control tap? Or is the boiler too weak or faulty?
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The boiler model you've quoted doesn't exist. Could you check again? Is it in fact a Main Combi 30HE, or possibly a Baxi 80HE?
Model = "Combi 30HE" or possibly "Main Combi 30HE" as written smaller elsewhere.
Make = Baxi Patterson

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