Baxi Solo 4 shuts down after few secs

[Michael]

I have a recurring problem with a Baxi Solo 50/4 RS. It's been running well for a while just providing hot water but it's now stopped and the pilot is out. When I light the pilot and create a demand for hot water it fires up but cuts out after about

10 seconds. In the past I have had to clean out the balanced flue because leaves had found their way in. I have also previously managed to get it going with lots of radiator bleeding. It is more troublesome when I am using it for heating - goes wrong more often. The boiler heats water in a cylinder upstairs where there is a 'finger' bleed valve. Have bled this extensively but no air seen. There is a feed tank in the loft and the water level is correct. I would like to get into the heat exchanger to see if there's any rubbish in there but it's not as straight forward as my old combi as there is some pipework (thermocouples?). If there is an airlock could the boiler overheat in just 10 secs? If above true then I welcome suggestions to deal with it as it would br great to have a hot shower!

[Ed Sirett]

What's the pump doing? Water in header tank? Zone Valves OK?

[Roger Mills]

It sounds like the water isn't circulating as it should. If there are no air-locks, are you sure that the pump is working?

[Michael]

here:

Just seen your post -Internet's playing up too!

The (Grunfoss) pump appears to run ok. I can see water swirling when I unscrew and remove the inspection screw. There's water in the header tank and the zone valve (Jones & Staefa) is ok. With the heating on there is no longer resistance against pulling the lever to the opposite position which happens with hot water set only. I have noticed that there is no separate expansion pipe over the header tank

- just the feed plus the normal c/w & overflow. I think I read somewhere that this can cause air-locks.

[Michael]

Roger, please see my reply to Ed

[Ed Sirett]

The next step is where experience helps, maybe the pump is air locked. maybe there is a serious air lock, maybe the pump turns but does not work effectively, maybe there is a blockage.

[Michael]

here:

the pump is able to work one day then fail then work again I suspect that there is an air lock as this is a recurring problem.

[Ed Sirett]

here:

Which then asks why is the air being drawn in to the system? Which again required a fairly careful investigation of the layout of the pipes.