Intermittent hot water from Grants Combi

13 Aug 2008
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United Kingdom
We have a brand new Grants Outdoor vortex combi boiler which gives intermittent hot water. If the central heating is on there is a constant supply of hot water. If the heating is off you have a 25% chance of getting hot water. The boiler sometimes fires up after 2-5 minutes and starts supplying hot water. Really driving us crazy as more often than not when the heating engineer comes out it gives hot water.
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it sounds like diverter valve but strange if the boiler is new this should not happen.
Diverter valve's not moving accross, common failure on these even from staright out the box. We've had so many problems with this and also the poor service from grant. Plus telephone call's where they blatently deny there's an issue with there current boilers even though we've had it countless times, that we have stopped using them all together for worcester.

Hopefully you don't live in Devon/Cornwall!

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I have had a look through the manual and can't find where the diverter valve is at. Clearly mentioned on the diagram for the combi max but not on the diagram for the vortex combi. Any ideas? Yes it is under guarantee.
Check the flow switch; might be sticking [a common problem, although Grants say theyve fixed this fault!]

Also check the water pressure to the boiler, it might be too high, if its above 3 bar, you need to install a pressure reducing valve.

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