No HW on a Vaillant TurboMAX 828

[peca27]

Morning all

I've got a 5yr old Vaillant TurboMAX 828, on which I changed the diverter valve approx 9mths ago. I am due to fit a Magnaclean + flush out the system within the next few weeks......in the hope that this diverter lasts longer than the last one.

Everything has been going ok until this morning when i turned on the HW tap but all i got was cold water. I left the tap running + went over to the boiler to check it out. Everything seemed fine on the boiler-ie, pressure + no error codes etc. BUT the water temp (a digital readout) showed only 19deg.

Now when the HW is working the boiler 'fires up' + the water temp increases upto + over 35/40deg (depending on what HW temp setting I have). But here the boiler didn't seem to be 'firing up' + the temp stayed at 19deg. I pressed the reset switch + all started to work again.

Is this a one off 'glitch' or a sign of a problem on the horizon? I spoke to my plumber who says it can't be my diverter again, as they usually last a few years on an un-flushed system + my system is fairly clean anyway. As I only had the diverter replaced Dec 2005, i've only had a few months of actual diverter valve use aswell (the heating hasn't been used at all since April 2006). So what's going on?

Cheers

 

[chrishutt]

So what's going on?

the boiler will tell you what it thinks it's doing. Press the i button for status codes and refer to manual. Does the boiler think it's doing hot water? If not, it's probably the flow switch (aqua-sensor?).

 

[Agile]

Its always better to exercise the boiler on heating for a few minutes every few weeks.

Leaving it for months without ever using the heating as tempting trouble.

In this case then the status codes may help but if resetting made it come on again then I would have expected a fault code perhaps for failure to ignite would have been displayed.

The flow sensor would not be "reset" but could always start to turn again if the boiler was slightly shaken or just randomly.

Tony

 

[ChrisR]

The flow sensor wouldn't cause a reset being needed.
What did the display say when it needed resetting - just checked, it would perhaps have been F28 or F29 if it had failed to ignite but a different one if the diverter had stuck.

 

[peca27]

Thanks so far

The problem is the display was completely normal, no error codes or anything, the only thing it said was 19deg. As I said, it would normally say 19deg before turning the HW on, but when you turn the HW on the degree reading would normally increase.

I also didn't hear the boiler 'firing up' as it normally would when the HW is turned on.

Also i don't think it needed resetting, i just reset it myslef b'cos i couldn't see any problem visibly. If it happens again should I press the 'i' info button?

Also ChrisR when the diverter valve failed originally i never got one error code, it just slowly stopped working.

 

[Agile]

Even if the diverter has failed there will be no error code because the boiler thinks its working properly.

If the DHW flow sensor was stuck then no error would be given as there would just be no demand for DHW shown.

It seems the sensor may have stuck. Its an occasional problem on your model.

Tony

 

[kevplumb]

tony can you e me please

 

[ChrisR]

iirc it's the status codes you can use to see if the DV is stuck, sorry, not an error code.