Vokera Sabre 28 - Hot water temp varying.


3 Jan 2006
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United Kingdom
Hi - need some info to determine if I have a problem or not !

New Vokera fitted as part of a complete new system in Oct. 2005. Since it's been installed we have an issue with varying hot water temperature - whenever we run the hot water the boiler constantly switches on and off resulting in water temp ranging from lukewarm to roasting. As a result of this we can't get the shower to function properly either (again, varying temp).

Is this normal (our first combi system !) or do we have an issue that we need to call Vokera service for ??

Please don't tell me how bad this boiler is - I couldn't stand it! - we fitted this at our installers recommendation.

Any help gratefully accepted.

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Lots of possible causes.

Was the system cleaned (flushed, with chemicals, takes a while...) when the new combi was put in?
It's often sludge in heat exchangers which causes this problem. Could also be a boiler problem, but as it's so new I suggest you call the installer. October's a bit new but if he left a load of acidic flux in the system, the radiators could be rusting merrily. They can perforate in 6 months. I don't know Vok's policy but they may charge the installer if it's a sludge problem - but they will not fix it.

COuld also be a water flow problem, unlikely unless something has just changed. Does it do it at all taps and flow rates?

Lets hope it's "just " a fault in the boiler!

This is a brand new system - everything - pipes, boiler etc. so no issues with sludge methinks.

This happens on all taps and at all flow rates - from trickle to full on flow.

Any other ideas ?
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Sounds like the wrong flue restrictor ring fitted. Check installation instructions to find correct size

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