Shower on megaflow (unvented) system fluctuating temperature

13 Apr 2011
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United Kingdom
I'm in a flat where the hot water (& cold) is centrally supplied to all flats on a mains pressure (megaflow/unvented) system.

The shower in my flat has a manual mixer (not thermostatic) which doesn't seem to keep a constant temperature it fluctuates making for an uncomfortable shower - one minute cold, the next too hot.

Could replacing the manual mixer with another manual mixer help?

Btw, the landlord doesn't want to chance it for thermostatic mixer - he says it's very expensive and break easily, and he hasn't had complaints from anyone else so far.
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I would measure the incoming temperature to the mixer tap to see if its arriving at a constant temperature.

If it is then there is probably some thermal oscillation occuring as the hot section heats up which is turning off the HW flow causing it to cool again.

I always suspect that its the jumpers expanding.

That is sometimes found with cheap taps. Changing the flow rate sometimes helps although with no control over incoming temperature makes that more difficult for you.


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