Baxi Solo Airlock?

I recently replaced a radiator after some decorating and now my Baxi Solo 2 overheats and trips out. It was working ok for about a week but I guess an airlock is the cause. What is the best way to get rid of the air? I have bled the radiators and the pump appears to be working ok. Thanks, Paul.

The short answer is bleed it from the system high points.

Concentrate on bleeding air from the area around the pump, if the pump works properly it'll push air into the rads where it will be easily bled off.

Turn the heating & hot water system ON, but the boiler OFF at its dial. You can sometimes get a pump to stop by moving the speed switch between settings, on the Grundfos 15/50 it's between speeds 2 & 3. So stop the pump, bleed air from the pump inlet, then start the pump. LISTEN for surging noises. Repeat the bleed process until the noises are much reduced - it no air comes out then you've done the job. Only then should you re-bleed the rads.

If the air persists check that the header tank is full and it isn't "pumping-over".

Thanks Meldrew's Mate. A couple of questions...will the pump still work with the boiler off? I seem to remember the pump shuts off about 3 minutes after the boiler stops. Also, how do I bleed air from the pump? Please excuse my ignorance but is it the large screw on the centre of the pump?

You can bleed some air from the pump itself, but that's a long winded way, what I meant was "bleed air from the pipework around the pump inlet", this is so the pump inlet always has some water to "push".

Where's the inlet? There's an arrow cast into the pump body pointing from the inlet port to the discharge port.

Remember, the air will always lodge in the pipework high spots, get these bled and the movement of water may push more air into that area. Bleed it until no more air comes out.

drain down fill up again start from bottom rads
or back fill the system with a hose pipe pushin air out up in to the tank

Your pump won't work unless the boiler tells it to. It is controlled by the boiler pcb. That is why as you say, the pump 'over runs' when the heating turns off.

Have you got 240V at pump during heating/HW demand?

Are you sure the system has re-filled fully? Do you get water out of the upstairs rads when trying to bleed them? If not could be a cold feed blockage. See FAQs.

Have you bled the system at the bleed point next to your HW cylinder?

Try setting pump on full and have just HW on and any bypass shut. Also try the same but all rads off bar the nearest one.