Vaillant ThermoCompact boiler - seems to keep coming on

I wonder if anyone could help me with a quick query please. Firstly, apologies for all the incorrect terminology as I am a total ignoramus about this kind of thing! I basically want to know if the following is just normal operation, or if it indicates a problem, please.

We've just moved into a rented house which has a Vaillant ThermoCompact boiler/hot water cylinder system. The boiler wasn't working - we suspected the reason was low pressure as it had dropped almost to zero - so the landlord got a BT Homecare guy round to check it today, who refilled the boiler which restored the pressure. He was then able to start the boiler for us using the controls up in the airing cupboard and confirmed that the cylinder was heating up - so far, so good.

After he'd gone and the boiler had finished heating up the cylinder of water, it turned off again as expected. However, since then it seems to keep coming back on every 5 minutes or so, then going off again - and this keeps happening.

To clarify what I mean by 'coming on' the following status codes appear. Words "in quotes" are the descriptions in the manual, those (in brackets) are my observations:
s2
s3 (ignition - only for about 5/20 seconds)
s4 "burner ignited"
s7 "water pump overrun" goes on for about 2 minutes (sounds like water is running through pipes inside it)
S8 - "Anti-cycling mode after heating operation" (boiler goes quiet)

The temperature dial is set about mid-way, the digital reading is varying between 50-52 degrees. Is that a reasonable temperature for hot water to be set at, or should it be adjusted?

This sequence then repeats about 5 minutes later. Should the boiler keep coming on briefly like this, or do I need to get back to the landlord again?
Thanks in advance for any help - sorry to be so ignorant!

Check to see if he has left your 2 port or 3 port zones in manual position.

If your system is covered by BG then would it not be best to recall them to investigate your problem.Sounds like its not a boiler fault but external controls fault.

turn the boiler thermostat up, the cylinder is probably set for 60c and the boiler is set at 50c so the cylinder will keep calling for heat, turn the boiler stat up until the display reads 75-80c.

Thanks, Picasso - turning the heat setting up as you suggested seems to have done the trick, saving another BG call-out. Thanks so much for your help!

dawkins said:

The boiler wasn't working - we suspected reason was low pressure as it had dropped almost to zero - so the landlord got a BT Homecare guy round to check it today, who refilled the boiler which restored the pressure.

Click to expand...

I thought that BT looked after telephones ?

P off agile an measure some thermisters lol!