Baxi Boiler shutting down help????

[Kes10]

Hi all,

Please bear with me, ive no real clue on heating systems, just want to try and save myself from calling an engineer out..

I have a Baxi solo 2 50 RS boiler which keeps shutting down after a few mins..

The pilot stays on all the time and overheat button does not pop out, so i dont have to reset it.

Ive been in the loft to check the pump which is spinning but the honeywell silver box just below it is buzzing (ive no idea what this is)

Sometimes the heating stays on for half hour or so, then shuts the main burners down.

I can see that the pilot light covers the thermocouple.

Ive bled the rads to check for air but they all seem fine....So im at a loss here...any ideas or things to try ???

Thanks

kes

 

[Hugh Jaleak]

Honeywell 'box' is a motorised valve, but I dont think it should be buzzing though..... On the side somewhere will be a lever marked MAN and AUTO. Lock this in the MAN position and see if the heating works.

How many pipes go to the valve, 2 or 3?

 

[Kes10]

ok ill go lock that into manual, this wont have a bad effect in the long run though ?

If you mean pipes into the boiler, there is two...both hot

 

[Hugh Jaleak]

No, pipes into the valve, you will probably have either one valve with 3 pipes connected, or two x valves with 2 pipes connected.

Putting it in MAN will get your rads warm, just means the room stat wont switch system off when room is up to temp. Valve needs sorting soon as possible really, but this should get you warm for now.

 

[Kes10]

2 pipes into the valve....

Also, the switch on the honeywell valve seems broken, it just loose when i go the switch it. How do i tell if its on manual or not ??

I can kill the power and open the box ? but what am i looking for ?

 

[Hugh Jaleak]

If the lever is loose then the valve should be open. When the valve is closed you should feel resistance on the lever, and hear it 'whirr' as you open it. The lever locks into an indent in the valve casing to 'hold' it open. They are usually spring closed, when power is applied the motor opens the valve, which then activates a microswitch to control the boiler and pump.

Is there hot water getting along the pipes to and beyond the valve? (I am assuming from your first post that your radiators are not getting hot?)

 

[Kes10]

yes theres hot water to and from the valve.

the rads are only luke warm due to the boiler switching itself off.

After about 15 mins it kicks back in again, only to go off again a few minutes later.

 

[Hugh Jaleak]

It sounds like a circulation issue, the boiler isnt getting the water away fast enough to the rads so the boiler stat switches the burner off until it cools sufficiently to fire again. I suspected the valve from your description as they shouldnt 'buzz'. It is always possible the pump is not working correctly, are you positive its spinning? (Undo the big silver screw and insert a screwdriver to check.)

Other possibles might be lack of water, check F+E (small tank) is approx 1/3rd full, or simply a sludged up system.

 

[Kes10]

Yeah its deffo spinning, though whether its spinning quick enough ?

I took the big screw off and can see it spinning, it has 3 speeds and ive tried the system on them all.

Ive tried draining some water out the system from the outlet valve on the rad downstairs, about 5 ltr...which quickly filled back up in the small tank in loft.

That is about 1/2 full and on the fill line and stops when the ball valve gets to its position

 

[nogoodatfaultfinding]

You have a blockage mate

Get a Strong Magnet and place it either side of where your 15mm cold feed Tees into the 22mm Return and Vent.
If it sticks your pipework wil need replacing in this area (Nearly always here).
You could then do with a power flush and a Magna clean for your system.

 

[Kes10]

You have a blockage mate

Get a Strong Magnet and place it either side of where your 15mm cold feed Tees into the 22mm Return and Vent.
If it sticks your pipework wil need replacing in this area (Nearly always here).

ok, I have no idea where you are talking about ? can you dumb it down a little for me... )

 

[Hugh Jaleak]

Hmmm, certainly enough water, doesnt seem there's blockage in the cold feed.... What colour was the water you drained out? Black indicates corrosion and sludge in system.

More questions im afraid. Is there a second valve after the pump? The pipe from the pump should split, one branch serves CH, (with the buzzing valve!) and the other goes to the hot water cylinder, should be another valve on this, (operated by a thermostat on the cylinder). Does this get hot, and have you an ample supply of hot water in the cylinder?

 

[nogoodatfaultfinding]

Hmmm, certainly enough water, doesnt seem there's blockage in the cold feed.... What colour was the water you drained out? Black indicates corrosion and sludge in system.

More questions im afraid. Is there a second valve after the pump? The pipe from the pump should split, one branch serves CH, (with the buzzing valve!) and the other goes to the hot water cylinder, should be another valve on this, (operated by a thermostat on the cylinder). Does this get hot, and have you an ample supply of hot water in the cylinder?

Im talking abut a blockage on the return not the cold supply!

You would always still be able to fill the system as the unblocked pipework would still get the water through.

Boiler firing up and cycling far enough that it stays on a while then thinks its reched temp and firing down then starting cycle again usually means blockage in said area.

OP - Go to your cylinder cupboard or your little feed tank, follow your 22mm pipe which just hangs over the tank and the 15mm (Usually) which feeds your tank back to the cylinder area.
At some point the 15mm will Tee into the 22mm and the 22mm will carry on to your valve.

The blockage will be here.

 

[Kes10]

When i drained the 5ltr or so water out the bottom rad, it was black for about 3ltr of it then ran clear.

from below the pump it T's off, one goes to cental heating with that honeywell box and the other goes to the cylinder with a tap in between (nothing else)

 

[Hugh Jaleak]

Try shutting the tap on the pipe to the HW cylinder, then see what happens. I think maybe the water from the boiler is taking the easiest route through the cylinder rather than having to go round the rads.