Potterton Flamingo does not stop heating

[Fishingsmurf]

I have a Potterton Flamingo boiler that is not heating up as it used to and I am concerned it may do something nasty if I leave it !

I have the hot water switched off, so just doing central heating at the moment, and have only just started using it again since the start of summer.

If I switch on the heating and set the room thermostat so it thinks it is not warm enough, the boiler fires up, and the radiators in the house get hot. If I then turn the thermostat down, the boiler switches off, so all is good.

However, the boiler used to burn for a few minutes, then switch off, and then start again, and keep doing this until everything was warm and the temp on the room thermostat was reached. Now, it fires up, and just keeps going......

I have not had the courage to leave it more than about 5 minutes as I am concerned it has a fault somewhere that may result in the boiler exploding?

Any advice most appreciated!
Paul

 

[kevplumb]

check the room stat/ boiler stat is working

ie turn them down does the boiler go out

 

[bengasman]

The boiler won't explode. If you want to check that the boiler stat works, turn it to 1, and see what happens. I expect the flow directly after the boiler would be about 50 - 55 degrees.
Try it with dhw off, and ch on.

 

[Fishingsmurf]

Room stat is working - I turn it to say 25C and the boiler fires up, then turn it to say 18C, the boiler shuts down.

When you say boiler stat, the only control has "min, 2, 3, 4, 5, max"....usually set at 3. Anyway set that to "min", about 5 mins ago....and the boiler is still going. If I turn that knob so it clicks off, the boiler goes out?

 

[bengasman]

So far, so good. Give it some time whilst on 1, and you will probably see it turn itself off, on, off................

 

[Fishingsmurf]

Boiler looks like it is behaving itself, just working differently than when last used. Previously it would fire up for a few minutes, then switch off, then back on again. Now it is firing for a lot longer before switching off.

Thanks very much for the input!
Paul

 

[bengasman]

The fewer cycles a boiler has per hour, the better. Bear in mind that the boiler must be set hot enough (about 70C minimum) to make sure the cylinder gets hot enough (at least 60C) the boiler should be set sufficiently higher than the cylinder to avoid cycling. Maybe this is what used to happen.