Vokera linea 24 .. DHW goes hot and cold

[spannor]

Ok Guys Here we go,

My DHW is going warm then cold.

I have watched the temp indicator on the boiler and with the tap in the kitchen open full the temp goes to 36-37c then the burners go out and the water temp drops to 27c ish then the burners re-ignite and the process repeats over and over .. this is quite annoying when in the shower as you can imagine its like doing the hockey cocky... any help would be great ....

I have played before so do understand a little,over the years i have replaced the pressure vessel and thermistors and motorised valves and Main Heat exchanger.

 

[kevplumb]

dhw heat exchanger clogged

 

[spannor]

Hi

Thanks for the reply... just to add, my misses is in the shower as i type lol. and i am watching the temp on the boiler and its going up to 56c ish and the the burner is going out... this is with the hot tap turned on just and the cold tap turned on just ( both hot and cold are only just open which is giving us a luke warm shower but seems to last longer before going Hot and cold ...is it still the DHW Heat exchanger? and if so would i be able to clean it out or is it a replacement part i need


Thanks

 

[kevplumb]

if so would i be able to clean it out or is it a replacement part i need

either they can be cleaned

be aware its also a sign of a dirty system

might be worth putting some cleanser in the system while your at it

 

[spannor]

Thanks again mate.

I will give it a go .. i have some fernox F3 cleaner somewhere.


i will post a reply if it works

Thanks again

 

[fanboy]

To be more helpful on this situation, and find out if your plate heat exchanger is needing cleaned or replaced, try the following.

Make sure hot water thermostat on the boiler is up as high as can be, then turn hot water on at whichever tap you seem to think it affects the worst.
Now under your boiler you have a lever to the right on your cold mains pipe, it should be facing vertically upwards at this point, keep your hand on it, DO NOT move it at this stage, now watch the burner and as soon as it cuts out, turn the valve your holding anti clockwise 90 degrees, that will shut your hot water off, which is fine. As soon as you have done that look back to the display l.e.d on your boiler and what temperature is it showing now?

I am guessing 93 .

don't forget to turn it back on again though XD. Good luck.

 

[spannor]

OK Mate i will try that in the morning as i am at work now. and i will post the result. If it does show 93c what does that mean??

does it mean that it needs changing or cleaning or is it a totally different problem.


thanks for the advice

 

[fanboy]

To me it means order a new plate heat exchanger less hastle, you can never properly clean these plates, the heating side that feeds to this part will be choked and dirty, doesnt have to be 93 maybe 85+.

 

[spannor]

Hi

Did the test you said to do.

And yes the temp went to 92c,

so i guess i will put some Fernox F3 into the system and run it as directed then rinse well then fit new plate.

Does that sound right?

Thanks for your help guys

I will post results when done it.

 

[fanboy]

no fit the plate heat exchanger mate then add sentinel x400 and then drain and add sentinel x100.

 

[spannor]

Ok mate thanks for that info.

i will do that

Thanks again

 

[spannor]

Fitted new DHW Heater plate today and yippeeee hot water ...

will run Sentinel x400 when it arrives

Thanks guys for all the help.



what do you guys think of the Magnaclean set up.

 

[kevplumb]

good

 

[spannor]

Hi again all.

i fitted a new DHW heater plate and run sentinel x400 through the system for x amount of weeks then flushed until clean water ran out then put x100 into the system repressurized and all seemed fine until now ( 3 months)

And now i am getting luke warm water then cold water running. i have noticed the boiler seems noisier than before and the pressure gauge needle is vibrating. i am getting no error codes and the central heating side seems ok.

Any more help you can throw my way will be much appreciated

 

[Andygasman2010]

To be more helpful on this situation, and find out if your plate heat exchanger is needing cleaned or replaced, try the following.

Make sure hot water thermostat on the boiler is up as high as can be, then turn hot water on at whichever tap you seem to think it affects the worst.
Now under your boiler you have a lever to the right on your cold mains pipe, it should be facing vertically upwards at this point, keep your hand on it, DO NOT move it at this stage, now watch the burner and as soon as it cuts out, turn the valve your holding anti clockwise 90 degrees, that will shut your hot water off, which is fine. As soon as you have done that look back to the display l.e.d on your boiler and what temperature is it showing now?

I am guessing 93 .

don't forget to turn it back on again though XD. Good luck.

Do this test again, it's very useful. If results are the same then the plate is blocked again. Maybe it's scale on the mains water side of the plate, have you got hard water in your area? It could also be sludge again, 3 months is enough time for it to build up. Only a propper powerflush would guarantee no more sludge.