Boiler swithes off after two minutes

[wozza]

My Boiler (Ideal Mexico - Super FF 2000) will switch off after only a short time and then will not start up again until it has been left a while. I have experienced problems since moving to house in October (Heating system previously dormant for 6 months) I have circulated and flushed the system with Ferox, taken off several radiators and emptied out sludge. I have recently freed the thermostatic valve on the final two radiators resulting in the heating system being fully operational for the first time. Two days later no heating at all. The pump is working (have removed and inspected) I guess I have a sludge or an air lock problem but cannot find it. Please help - Kids are very cold!

[Peter Scott]

I don't know this boiler and use oil myself but I guess the problem might be a generic one.

The fact that it switches off, then will allow itself to be started again after a while, suggests that a thermal safety switch is tripping somewhere, probably in the boiler. My boiler has an over-temperature cutout. This was tripped once when a son turned off the rads and turned the boiler up full when I was on holiday!! Yours must reset itself.

Either the cut-out is faulty or something is restricting the water flow and causing it to overheat. Can you hear a sound that would suggest near-boiling just before it cuts out? How old is the boiler. Is trip failure likely?

If you don't get hot sounds my guess is the cut-out. If you do get them, then there is poor flow probably due to sludge.

Last thought. Is this is an old-style non-sealed system? If so you might have low water level due to a stuck header tank refill. Peer in the tank to make sure there is water. There still might be a block in the downfeed pipe. Do all radiators bleed OK?

Peter Scott