Baxi 80e instant combi overheating

[PRplumb82]

Checked the gauze on return today which was clear, boiler is still not working correctly on CH, or HW now either!

on CH from cold, boiler fires up, goes onto full burner but then immediately drops down to a low flame, the temp dial on the front panel shoots up to 80 within seconds and flow pipe is red hot, literally within 10 seconds

With demand on HW boiler fires up and stays on full burner for bout 1min - boiler temp shoots up to 80 then boiler shuts down - the HW outlets are just luke warm through out this process with the odd surge of hot water.

on both HW & CH they repeat this process a few times then fault out on high limit stat..

do you think I could have a blockage in primary Heat ex or diverter valve?

 

[PRplumb82]

Could do with some help on this one lads..

 

[bigads28]

What condition was the water you took out of it?

I'm still sure its blocked if you've changed the pump. Get a strong magnet and start checking the pipework in the boiler. I've had blockages on diverter ports and the pump connections. The magnet makes finding them quick!

 

[Leo21]

Double check the boiler isating valves are open, they can sometimes spin on there cam. Making you think you've turned it on. Take the divertor head of and see what works. The fact that it's deteriorated must be linked somehow to what you've done.

 

[PRplumb82]

Water condition was fairly dark - I was thinking of power flushing the system and hoping that shifts any sludge in the boiler.

checked the F&R valves which are open, heating does eventually get round to the rads and return just have to keep resetting it....it goes like this - CH demand, boiler on, boiler overheats, flame off, pump over run, heat gets round to rads (only small system 4x rads), boiler cools, fires up, and so on, after about 3 times it then locks out

I dunno, think I'm going to do a power flush and hope for the best

thanks for your feedback tho lads much appreciated

 

[bigads28]

I really think you'll not make any difference flushing the system. It sounds like its restricted down to a hole the size of a biro! I'd use the magnet and a few fibre washers and hunt the blockage down.

Like this one!!

 

[PRplumb82]

Bloody hell!! Lol

Prob a stupid question but here goes, how does it work using a magnet and fibre washers to locate a blockage?

 

[bigads28]

Bloody hell!! Lol

Prob a stupid question but here goes, how does it work using a magnet and fibre washers to locate a blockage?

Well most pipe in your boiler are copper and the valves etc are all brass, the magnet won't stick to those. Where you have a build up of magnatite the magnet will stick. Strip it out, dig out the blockage and the fibre washers are for putting it back together.

The magnet applies to systems if you are hunting blockages, makes finding the blockage in a cold feed really easy!

 

[PRplumb82]

Thanks bigads28 will try that tomo n let by kno how I get on

 

[bigads28]

Thanks bigads28 will try that tomo n let by kno how I get on

Throw that gauze filter away too, they are just a pain too!

Good luck make sure its a decent magnet though no a fridge job!