Thorn Apollo - pipes bang and boiler shuts down after 30s

[whaler]

I am looking for some advice on a problem with my Thorn Apollo boiler and open vented heating system. Over the weekend, I took out my old bath suite and replaced it. This all went well, including the replacement the radiator.

I had turned off the hot and cold water feeds in the loft to drain the hot and cold pipes, but didnt drain the CH for the radiator (just cut the pipes and used push fits to quickly connect the pipes, but lost very little water).

Rather stupidly , I didnt turn off the boiler timer, so whilst the water feeds were off the boiler kicked in. Now, when I turn the boiler on, it fires up, making a slight whoosing noise, then the pipes above the boiler make a loud banging noise and the boiler soon switches off.

So, I assume that for one reason or other, the water is not circulating thru the boiler and overheating, therefore triggering the boiler to switch off. I have checked all the rads and water is coming thru the vents, little or no air.

Could anyone kindly advise what the best method would be to cure this (as we currently have no hot water to enjoy our new bath etc. ) From reading the other entries I guess this might be to drain the system, to ensure there are no air blocks) or that the pump might need replacing. Could you confirm how to check if the pump is gone or if the pump overrun thermostat needs replacing?

Many thanks!

 

[kevplumb]

undo the big silver screw on the pump water will dribble out use a small screw driver to check if the shaft is turning

 

[whaler]

Thanks for this reply, in the end I checked the pump, when the CH was started there was motion, the spindle didnt turn around. I knocked the pump a little and the spindle did try and rotate but only for 5 seconds.

Eventually I got the cordless drill and span it myself with a screw attachment, for about 5 mins. This seemed to dislodge the problem and the pump has been fine every since!

 

[PTH]

Well done for sorting it out. But, it is likely to happen again, so be prepared! Pumps are not that expensive so it could be worth changing it anyway, or, if it's muck settling in the pump body you may wish to consider flushing the system.