Vokera Linea 28 hot Water Problems..Advice please

[Sarah2]

Hi, My boiler (8 years old) is causing problems with hot water supply to the bathroom. The water downstairs runs hot when the tap is turned on at any power, but uostairs, the water only runs really hot if the water is run at a low speed. The boiler has been looked at 4 times now by a corgi registered engineer and the venturi has been cleaned and new valves have been put in (sorry can't remember which ones) The engineer now says that he believes it to be a problem with either the thermostat on our Aqualisa shower letting in too much cold water when the shower runs and having a knock on effect on the taps when they run after this. Alternatively he says that the cold water pressure coming into the house is too high and is affecting the boilers ability to keep the water hot. He says that the boiler is absolutely fine...does this seem reasonable??
- when the shower is running, if it is run on a lower heat setting for a minute and then the heat setting is increased, we get lovely hot water for about a minute then the temperature drops again.

 

[nickso]

hmm, quite a lot of things could be happening here. shower could indeed be faulty but if the bathroom taps are affected its more likely to be a boiler fault IMO.

he has maybe done this but i would check the diverter isnt passing, the the dhw h/e isnt scaled, flow rates to all taps/shower are ok and that the boiler is modulating properly.

 

[DP]

The fact that taps downstairs have no problem giving you hot water, I have to say boiler is fine.

WRT to shower, whilst having a shower, run a cold tap in the bathroom and see if shower delivers acceptable hot water.

Excessive mains pressure will not cause the boiler to NOT heat water- it will be delivering stipulated flow of water (unless someone has tempered with it)

 

[Sarah2]

Thanks for your replies, I believe that he replaced the diverter valve today because he was concerned that some water was going around the central heating system instead of the hot water sytem (hope this makes sense)
I am going to contact my plumber tomorrow to check out the shower.
I just keep thinking that there must still be something wrong with the boiler because, before we started having these problems we had hot water at good pressure upstairs whenever we needed it through the taps and the shower but now we have neither.

 

[Sarah2]

Sorry, forgot to say - when the engineer ran the shower with the cold tap running in the bathroom, the temperature was much better.

 

[DP]

>>>>The water downstairs runs hot when the tap is turned on at any power<<<
If diverter was defective, hot water downstairs would be problematic as well.

Have to say once more, do not think there is a problem with the boiler. It is a bad idea to start changing components based on suspicion alone. It might have been prudent to check the CH pipes before diverter was 'changed'. It is hoped the guy cleaned and greased the diverter spindle as this can start leaking at the gland nut. Diverter can comprise three components. Shuttle, diverter motor and the manifold. Wonder why the plumber would carry these items unless he came prepared or carried them as stock items (in which case his understanding of Linea should be much better than poke and hope that has gone on so far).

Running the shower with cold tap running proves the cold pressure is high. Shower cartridge is not coping with very high cold pressure and metered hot water from the boiler.

 

[gas4you]

Might sound a bit stupid, but is your shower rated for mains pressure/combi use?