A boiler with a mind of it's own!!

[Coolhurst]

We have recently moved into a new house which has a Vaillant boiler with a megaflow water heater. I've noticed the boiler seems to spring into life very early each morning (before any timer is due to set it off), for about 30 seconds at a time, before shutting down again for about twenty minutes and then doing it all over again. I know this as the flue is level with our bedroom window so it's waking me up. I've checked all the settings, timers etc. and everyhting seems fine. So even though no one is up using the hotwater why does the boiler fire up so early and for such short bursts of time? Is this normal? Frankly it's driving me round the bend and need to sort it before I move bedrooms or the boiler!!

i'm no expert on this stuff so any advice appreciated.

 

[chrishutt]

It might help if you say which model of boiler.

 

[justqualified]

If its a Turbomax i believe it has a hot water pre heat which kicks in at 40 degrees. If there is a green light permanently on at the front turn the hot water thermostat right down and the green light should go off, then set your water stat to whatever you wish. To turn it back on turn stat to max and set as before.

 

[simond]

It's unlikely to be a turboMAX because this is a combi; more likely a thermoCOMPACT.

It could be that the controls have been wired incorrectly, should take timer perm live feed and controls feed from pin 3 only and then through controls to pin 4 on PCB. If you wire live into pin 3 the controls are on all the time, similarly if you wire conventional switched live to pin 4 the boiler on off switch will be bypassed when boiler I/0 switch is off.

Clear as mud, I know what I am trying say.

 

[Coolhurst]

thanks for the speedy replies.

Boiler is a Vaillant Thermo Compact.

I'll turn down the water temp gauge to 4 and see if this has any effect.

Simond, your response sounded impressive, even to a layman like me! Know anyone in N. London who could help me?

 

[Agile]

Now is this really a new house or an old house which you have moved to?

If its really a new house then you should call the builder/developers under their guarantee.

If not then you should call a competent local engineer.

Tony

PS is the timing for hot water OFF at these times? Otherwise the thermostat will call for heat every 20 minutes as the cylinder cools.

 

[chrishutt]

Agile is an excellent heating engineer and covers north London, I think. Go to his profile for contact details.