Boiler Cut-out?

[Brom]

I have a Ideal Classic FF350 Boiler & Storage? unit upstairs. I bled the radiators the other day as there was not much heat to them. Loads of air came out - used the release switch on the flexible pipe to allow more water in. Now, the boiler will switch on for about 2 minutes, then go out. It will then not respond to being switched on for 1hrish when you can switch it on for 2 minutes again.

any ideas?

 

[Softus]

What is the pressure reading on the gauge when the boiler is cold?

 

[Brom]

just over 1 1/2

i don't think it changes.

 

[Softus]

If it never moves then that reading can't be trusted.

Some gauges have an user-adjustable reference indicator - if yours has one then are you sure that you're not just reading off that?

If not, then take more readings as follows:

a) after venting a rad with the system off;
b) while repressurising;
c) when the system is fully up to temperature (or after 2 minutes, whichever is the longer!).

 

[Brom]

Thanks for the reply.

I have probably not been clear... the reading has changed, when I bled the radiator, I meant it doesn't change when the boiler comes on. Also, the system never heats up as I can't get it running for more than 2 minutes.

So I guess the anwser to the above is the reading is currently staying the same, despite the 2 minute heating blast. Is this making any sense?

 

[Softus]

OK. Can I get picky?

Please time the period that the boiler stays on, and please determine whether or not the burners are actually lighting.

Also, when the boiler is "on", what noises is it making? Are you able to identify the pump to check that it is running?

Also, when it comes on, what indicator lights are showing? And again when it's turned itself and is refusing to operate again?

Also, please determine where the heat goes, if there is any. For example, which parts of the boiler are hot/warm, and which pipes leading from it are hot/warm.

 

[Brom]

>>OK. Can I get picky? ==> yes

>>Please time the period that the boiler stays on, and please determine whether or not the burners are actually lighting.

I'm not at home now - but will time it. Yes the burners are lighting, on full

>>Also, when the boiler is "on", what noises is it making? Are you able to identify the pump to check that it is running?

Boiler makes "normal" running sound, a background humming noise and then the sound of the burners coming on (which you can see)

>>Also, when it comes on, what indicator lights are showing? And again when it's turned itself and is refusing to operate again?

No indicator lights to check.

>>Also, please determine where the heat goes, if there is any. For example, which parts of the boiler are hot/warm, and which pipes leading from it are hot/warm

Hmm... will need to check pipes. The boiler itself warms a little, more toward the top.

I'll check the ones I couldn't anwser now when I get back.

 

[Brom]

I checked, time is 2 minutes and all the pipes were cold... however, i noticed later the hot water seemed to come back, so I turned the boiler back on and all seems fine - a lot of noise to start off with, and one radiator is now stone cold, despite the other being piping hot!

Could it be air stuck in the system that caused this?

 

[Softus]

Possibly. If you think that's the case then go looking for vents everywhere - above boiler, near cylinder. Also, vent every rad again with the system OFF, repressurising as required.

Turn off all the rads that get hot, leaving open the ones that are cold. Turn the boiler temperature to max, and the pump speed also. Note where they were so that you can return to normal later.

 

[Brom]

Cool

Thanks very much!