Hi All, this is my first post, so forgive me if I don't get the protocol quite right...
I'm repairing a Vaillant Turbomax Plus 824e for a client and have come across a problem I've not encountered before.
The boiler was unused for a long period of time and had a couple of standard problems that I resolved (Diverter valve needed changing and AquaSensor had to be cleaned as it wasn't detecting DHW flow properly).
There now seems to be a further problem with the domestic hot water (CH is fine):
When the DHW is run in any circumstances (CH on or off, Warmstart on or off, etc) the temperature fluctuates periodically by around 25C as:
- the burner ignites up,
- gas flow increases until the flow temperature peaks (e.g. 85C)
- then the burner turns off
- boiler waits a few seconds until flow temp reduces (e.g. 60C)
- then the boiler ignites and the cycle starts up again.
The whole cycle takes about 30 seconds.
It doesn't make a difference what the set point for the DHW is on the facia controller.
I can't work out what is happening. There is no fault code and all the diagnostic codes seem to be fine.
The worst thing is that before cleaning the AquaSensor I don't think the problem was there! (Although I may have just missed it).
Does anyone have any tips on what the problem could be and how to resolve this?
Thanks in advance.
Katie
(London)
I'm repairing a Vaillant Turbomax Plus 824e for a client and have come across a problem I've not encountered before.
The boiler was unused for a long period of time and had a couple of standard problems that I resolved (Diverter valve needed changing and AquaSensor had to be cleaned as it wasn't detecting DHW flow properly).
There now seems to be a further problem with the domestic hot water (CH is fine):
When the DHW is run in any circumstances (CH on or off, Warmstart on or off, etc) the temperature fluctuates periodically by around 25C as:
- the burner ignites up,
- gas flow increases until the flow temperature peaks (e.g. 85C)
- then the burner turns off
- boiler waits a few seconds until flow temp reduces (e.g. 60C)
- then the boiler ignites and the cycle starts up again.
The whole cycle takes about 30 seconds.
It doesn't make a difference what the set point for the DHW is on the facia controller.
I can't work out what is happening. There is no fault code and all the diagnostic codes seem to be fine.
The worst thing is that before cleaning the AquaSensor I don't think the problem was there! (Although I may have just missed it).
Does anyone have any tips on what the problem could be and how to resolve this?
Thanks in advance.
Katie
(London)