Heater doesn't start before i use hot water.

[Jose Afonso]

Hi,
I have one Saunier Duval F24e, in the house that i am living at the moment.
The Boiler was working perfectly till a mouth ago. But Now when i want to turn on the heater the first time of the day, the boiler try to start, and 5 sec after stops and the red led (fault light) goes on.
But i found out, that, if i turn on the hot water from the tap, let it run a while and then still with the hot water running, turn on the heater, it start working perfectly, (i hear the water running, and all the heater/radiator in the house get hot .)

After that, if i turn off the water and the heater, and one or two hours later, i'll try to turn on just the heater, it works amazingly!

But on the next day all over again!

The flat is rented, and i will contact the agency any way, and they will get me a engineer.

But i would like to know if any one have any ideas, what could be? Any think that i could try first?
Any way, if its not a easy job, ill just wait for the engineer.

Thank you.

 

[jackthom]

When the system is cold take a look at the pressure dial on the right hand side of the boiler. If it's well below 1bar that will be the reason it's not running for heating.

The pressure rises when the water is warmer and could then be just high enough to keep the boiler happy.

If this is what is happening you will need to find the filling loop which provides water from the cold supply to top up the system. The pressure on the dial should be just over 1 bar when cold.