S plan fully pumped boiler switch off every 2-3 minutes

[badri]

Boiler switch off every 2-3 minutes. Advise needed please, below is system speciffication


System is fully pumped S plan 3 zone with Honeywell Auto-bypass valve following are the specification.

Boiler: British Gas 330
Pump: Grundfos Pump
Valve: 2 into Honeywell 22mm 2Port valve &1 into 28mm 2port valve: 1>Heating Downstairs. 2>Heating Upstairs. 3>Heating Hot water.

Programmer: Drayton 742R Mitime programmer
Cylinder stat:Wired Drayton Cylinder stat
Room Stat: No Room stat

I have wired as per system specification as below.

Untitled

• badri
• 18 Mar 2014
• 1

 

[dcawkwell]

Manually open the 2 port valves does that cure the problem.
It the boiler keeps shutting down it sounds like no circulation going on.
Perhaps pump has failed.

 

[badri]

Pump is running I can see the noise of water circulation. But boiler switch off every 2-3 minutes and fire back after 5-6 mins. Rads are cold aswell.

 

[mogget]

What differential pressure is the auto bypass valve set to?

I know I am obsessing about that component again but I am wondering if it hasn't been set up whether the heated water is flowing straight back to the boiler.

Is the return pipe to the boiler hot?

 

[dcawkwell]

Pump is running I can see the noise of water circulation. But boiler switch off every 2-3 minutes and fire back after 5-6 mins. Rads are cold aswell.

No circulations going on. You have a blockage.

 

[TCCHeating]

Is the system sealed or vented? If it is sealed check the pressure is correct (around 1 bar when cold). If it is vented, check there is water in the f/e cistern. Also there may be a blockage in the feed pipe from the f/e cistern. Otherwise as previously said, your pumps prob to blame

 

[badri]

Mogget ..Yes return pipe is hot...

Yes there is Auto-bypass valve .I think 0.2 bar as default. Rads are slightly hot...

 

[badri]

its vented system...pump is set to maximum speed and I can see pump is running and piping hot!!

 

[mogget]

If pump is a UPS 15/50, try setting the auto bypass to 0.35 bar, see if that helps, if system has been drained down you may have airlocks, and as the system has been reconfigured you may need to re-balance it.

 

[dreadnoughtheating]

And there was me thinking it may, just may be a 'fault' on the motorised valve, acknowledged by Honeywell Techies, that affects some (and in their words, "German") boilers, causing 'cycling'.

Cured apparently by positioning a capacitor in the wiring centre.

(the BG330 is a Glowworm - owned by the Vaillant - German- parent group, and maybe considered the Vaillants ugly sister)

Just a thought.

DH

 

[badri]

And there was me thinking it may, just may be a 'fault' on the motorised valve, acknowledged by Honeywell Techies, that affects some (and in their words, "German") boilers, causing 'cycling'.

Cured apparently by positioning a capacitor in the wiring centre.

(the BG330 is a Glowworm - owned by the Vaillant - German- parent group, and maybe considered the Vaillants ugly sister)

Just a thought.

DH

2 port valve is switching on the boiler and pump. how can they shut off? I checked the valve lever it was easily moving(open) when boiler was on and aswell as boiler was off....it may be something else?

 

[dreadnoughtheating]

Apparently, they can feed low voltages back to boiler PCB's and cause firing...

As said, just a thought if everything else is proved oakiedoakie

DH

 

[Armo74]

Did you say you have no room stat?

 

[mogget]

Did you say you have no room stat?

Yes, I noticed that too, I hope he's going to install one, being a legal requirement these days...

 

[mogget]

Apparently, they can feed low voltages back to boiler PCB's and cause firing...

As said, just a thought if everything else is proved oakiedoakie

DH

That's very interesting. Fortunately my 'German' boiler doesn't suffer from that problem, but it's not the same model as Badri's, will put this one away in my brain though