I am having problems drawing hot water from my Vaillant Turbomax boiler. Sometimes it will be fine but most of the time it takes an age, if at all, to get any hot water through.
The diverter valve was replaced at the beginning of the year so I do not think it is this. The central heating is fine.
The green demand light flashes but the boiler does not fire up. It makes no difference if the heating is on or off, it is alwyas the same!
Any ideas?
Have you interrogated it for the fault codes? Look in your manual. I take it it has an LCD display.
Andy.
I have just had a look at the fault codes and there there is no record of any faults in the memory.
Ben
You need to do some fault-finding. I would do some basic experiments first of all to elicit what the boiler is actually doing.
First thing I would do is check if the boiler actually lights when you turn a hot water tap on. Although you cannot see the flame with the front panel on its easy enough to hear it 'whoomph' and you can see hot exhaust issuing from the flue.
If it lights and stays on, but you get no DHW it would blow up, because the heat couldn't escape from the primary heating loop UNLESS it was actually going to your CH. I see you've had a diverter valve changed but you must eliminate it from your investigation. Also, does the diverter make the usual changing-over noise when you have the CH running and then turn the DHW on at a tap? I can hear it do that from my bedroom if its quiet and someone turns a tap on as the sound transmits via the pipes. If the boiler lights but you get no hot water, try this experiment when the CH is off and see if hot water is still in fact getting to the CH pipes and radiators when it shouldn't be.
If the gas lights momentarily when you open a hot tap up, but then goes off, or it doesn't light at all, that could indicate all sorts of things. I did hear that some of the Turbomax units suffered from air pump faults ( I presume this is the centrifugal pump that sucks air in for combustion, or maybe they meant the sensor which detects the pump is running via the change in combustion chamber pressure - there are various interlocks which will not allow the unit to fire up if the sequence of events doesn't happen right ).
I should try the things I suggest unless someone else magics up an answer, then get back to the group and say what happened, diagnosis needs lots of evidence,
Andy.
Andy,
Thanks for your response.
I have looked at the pointers you made and have established the following:
The boiler fails to light immediately when I attempt to draw hot water. Sometimes it can take minutes to light other times it just doesnt and rather than waste water we give up.
The diverter valve works fine and there is no hot water escaping into the CH system when hot water is drawn.
The green light flashes indicating there is a demand for hot water but the boiler does not light up. The fan runs as if it is about to fire up.
I noticed this morning that the water temperature, when I eventually got some hot water through, fluctuated from hot to cold.
Many thanks,
Ben
And the yellow LED should light up
True the stock fault was on the APS switches. But then the OP wouldn't get any heating.
).
I would say its odds-on this is the APS (about £40).
As a final check I would consult section 10.6 of the manual and look at the value of parameter d.24 which is the return from the APS you will probably see this moving form 0 to 1 and back even though the fan is running all the while.
DO NOT take the APS out to check it will go down hard as you touch it, buy the replacement FIRST.
The repair requires no tools. Simply turn off, remove the old unit (accessible from above), swap the leads and tubes, and clip it in place.
Ed,
Finally I have been able to check diagnotsic mode 24 and it does flick between 0 and 1 when hot water is being drawn.
Should I therefore assume that it is the APS that requires replacing? Would this switch also be the cause of not being able to draw any hot water for ages as well as it fluctuating in temperature?
Also, why does this not affect the central heating system which seems to operate perfectly?
Thank you very much for your help. Like many others have found, you are a life saver!
Ben
I had a Vaillant fitted in my previous house about 6 years ago and had the Diverter valve replaced about 10 times....I did find that recycling the whole boiler worked for a while (i.e turn the green nob off, wait a bit, turn on again...then the hot water would work). Note, this only worked for a few weeks before the diverter valve packed in completly...apparently some manufacturing fault with the diverter valves back then...
Ant.
The problem is that the APS is _literally_ flapping in the breeze. For HW this cause fluctuations and delays. With the CH provided the flame on time is a sufficient proportion of the time you will have the a proportion of the 28k available. Which is likely a factor of several of what's needed to run the CH in Autumn. When the diverter valve goes down you some times don't get any heating.
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