British Gas 330 Boiler Locking Out !

[Monkey Wrench]

[FONT=&quot]We have a British Gas 330 system boiler (not combi) which was installed about 3 years ago.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]Recently the boiler has been locking out (green burner light goes out) after running for about 10 minutes. This happens on hot water only, heating only or both. The system is S-Plan and all[/FONT]
[FONT=&quot]diverter valves are working correctly. During the time the boiler is on the flow/return to the cylinder both get hot/warm and rads start to warm-up so I guess its not an airlock.[/FONT]
[FONT=&quot]Additionally, the bathroom radiator acts as a bypass and this warms-up as normal.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]The F&E tank water level is correct and draining some water from a radiator caused the F&E tank ball valve to open so the cold feed is not blocked.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]I have today changed the 18 year old pump and this has definitely improved things (boiler stayed on for 30 minutes with temp stat on high) but the temperature[/FONT]
[FONT=&quot]of the water circulating through the boiler is still getting hot far too quickly (up to 80C within 15 minutes from cold) and the boiler is still locking out.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]My only assumption now is that there is some debris (or blockage) in the heat exchanger restricting the flow which, if this is the case, I will call someone into to fix.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]Any helpful comments would be appreciated. Thank you.[/FONT]

 

[SimonJohns]

You say locking out?
Do you mean burner turning off
Or do you mean you have to reset the boiler

 

[Monkey Wrench]

Hi,

Thanks for the post SimonJohns.

Sorry, I think my statement "locking out" was a bit misleading. Basically, the boiler is getting up to the preset boiler thermostat temperature very quickly and the boiler thermostat is doing its job and turning it the boiler off. The boiler obviously stays on for longer with the stat turned to max but the boiler is still getting up to max temp far too quickly and then shutting off. I have not had to reset the boiler using the reset button.

 

[Hardy1]

could be the thermostat is gone, get it checked

 

[SimonJohns]

I'd say circulation issue or faulty stat

 

[Ryster]

If you have just changed the pump then I would almost likely say its a circulation problem and not the stat.

 

[RoryD]

Do you have a bypass? is it set correctly? Hopefully you installed the pump the correct way around, sorry if you are all about, have to ask mate. Wondering, If you have a BG 330, why aren't you on contract?

 

[TipTop]

Blocked/restricted heat exchanger mate-can you hear it 'cooking up' when on at app? powerflush the boiler/replace heat ex

 

[Neilsy10]

Common fault on these cylindrical heat exchangers is for the ports on flow & return entry into the geat exchanger become restricted it doesnt take alot they are small bore! after ur pump replacement it puts more circulation through the system hence staying on longer. Turn stat up to max if it kettles or bangs there is muck/scale in heat exchanger, investigate unblocking ports & a sonic cleanse to unblock and remove debris from heat exchanger cheaper than replacement!

 

[Kev the gas]

a sonic cleanse?? please explain

 

[Neilsy10]

Basically plunged into a deep steel bath which has a heating element in, using a fernox cleaning/ descaling acid solution operated at temperature then neutralised takes all the dirt & scale out the eat exchanger pretty impressive when seen in action did a mini one on a plate to plate heat exchanger on a combi good as new BG do it

 

[GrahamM]

The sonic cleaners can be used on plate to plate h/exchangers. B/G will do this if have a machine available. Rather than fork out for a new plate h/exchanger.
First I heard of one being used to clean a main heat exchanger in a GlowWorm HXi. I thought the only option here would be to flush it through or change it if was that badly chocked.