Help required boiler not reaching max temp! VAILLANT 28E

I have had the boiler for 3 years, has worked fine even in winter with cold feed. Boiler is Vaillant turbo max pro combi 28e. Noticed water wasn't getting to max temp anymore always had dial on max. Heating is still fine. I have a pretty good understanding of boilers etc just wondered if sensor is holding it off. or if anyone has any idea of what might be going on.
Thanks
Harvey

 

I presume your boiler is what I know as an 828 !

A common fault is the diverter valve fails after 2-3 years.

A test is to see if the rads get hot when hot water is taken for a while!

Its very unlikely a sensor has failed in your situation.

Much more likely that the plate HE is blocked if the hot water is not as hot as the spec shows.

You should never operate the dial on maximum! The display only shows the system boiler water temperature its NOT the actual hot water temperature!

Tony Glazier

 

many thanks for that! I will check it out afetr work.
Regards
Harvey

 

Why can't I operate it on max, as it is needed for showers. Sorry, I don't know the term "plate HE" the help is much appreciated.
Regrds
Harvey

 

H E heat exchanger its what heats your hot water

 

The temp knob on the boiler controls the MAXIMUM temperature the water can reach.

It does not do anything when the temperature is limited by the power input and the flow rate of DHW or by a fault.

The knob should be set at the temperature which is not going to seriously hurt you when you put your hand in it at a LOW flow rate of say 4 li/min.

Tony

 

I have already flushed out heat exchanger, and no apparent problem.
Thanks for all replies, and any help is gratefully recieved!
Harvey

 

I usually set DHW stat to 55C.

You have not answered Tony's question as to whether the ch flow pipe gets hot when you run a hot tap?

 

Sorry, I skimmed the answer from Tony as I was in a rush. No hot flow to rads when water taken. guess it must be diverter valve as suggested. Many thanks for the help.
Harvey

 

Wrong way around The dv would be faulty IF the ch flow got hot when a hot tap is used

 

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