Vokera 24 Linea - DHW

[Patel]

Hi,

I have a Vokera Linea 24 model boiler and recently seem to be getting problems whereby hot water is provided to the taps for a short period of time then it goes cold and the hot again and so on, the pressure bar is on 1.5 bar and central heating seems to be ok. Any ideas what is causing the problem. Thanks in advanced.

 

[Jezzy]

change DHW thermistor

 

[nickso]

thats one possibility

 

[scatmanjohn]

My money is on the dhw heat exchanger being sludged up.

Just as it cuts off,quickly turn off the hot tap and watch the display on the front.

If its approx 90 deg then the fault is with the hw heat exchanger.

 

[Agile]

Jezzy, can you explain exactly how a DHW NTC could cause that effect?

 

[Patel]

Thanks guys,

I have already purchased a 'High Limit Thermostat' is that the same as DHW Themistor? Will try this first if not will try the Domestic Heat Exchanger any idea how much this would cost?

Thanks again for you assistants!

 

[Agile]

Better to clean or replace the plate HE and not waste your time on anything else.

Tony Glazier

 

[Patel]

OK will give that a try tomorrow, failing this what else could be the cause of the problem?

 

[Agile]

Nothing else has failed!

Tony

 

[corgiman]

My money is on the dhw heat exchanger being sludged up..

me too I'll have some of THAT action

 

[Patel]

Appriciate your help, will let you know how I get on!!

 

[Jezzy]

Ask 'Nickso' or alternatively read page 34 of the Linea 24 manual. I've seen this changed and it cure this same problem (whilst training) and as its the cheapest option is usually the first one applied before changing the heat exchanger. The sensor senses the temperature of the water and modulates the gas valve accordingly, if this is faulty it will wrongly modulate the gas valve and give cold / hot water as described. Thats how i understand it anyway. If i am wrong will someone let me know what exactly they do do.

 

[jaynishriya]

I had a similar problem on my Halstead Wickes Combi, and (thanks to this forum) took the trouble of cleaning the DHW exchanger (with citric acid), drained and later flushed the entire system with Fernox Restorer and thankfully its all working fine. Need to add the inhibitor though, after sorting out some air traps in the system, and keep the system always clean (its easy to neglect).

 

[we88ie]

Hi,

I have a Vokera Linea 24 model boiler and recently seem to be getting problems whereby hot water is provided to the taps for a short period of time then it goes cold and the hot again and so on, the pressure bar is on 1.5 bar and central heating seems to be ok. Any ideas what is causing the problem. Thanks in advanced.

my Linea 28 was doing the same except I only noticed it during a shower.

I changed the heat exchanger as it was leaking DHW into the heating system and raising the pressure until the saefty lifted.

I also found the DHW thermisitor all crudded up so cleaned it

I've had no further problems since and the water is hotter than ever

Webbie

 

[Patel]

I had a similar problem on my Halstead Wickes Combi, and (thanks to this forum) took the trouble of cleaning the DHW exchanger (with citric acid), drained and later flushed the entire system with Fernox Restorer and thankfully its all working fine. Need to add the inhibitor though, after sorting out some air traps in the system, and keep the system always clean (its easy to neglect).

Hi Jaynishriya,

May sound like a silly question, where can I buy Citrix Acid or Fermox Restorer?