FF250 tripping on H/W only

[nalanosboh]

Hi,
New on here and looking for some help with my Boiler/hot water.
Got an Ideal Classic ff250 its over 15 years old but been very reliable, problem is the boiler overheat trips out but only on hot water - all ok while the heating only or heating and hot water is on.
Tried a new thermostat on the hot water tank and motorised valve but no better, pump seems to run ok and no problems with the cold feed from the F&E tank.
Started cutting out every few weeks then 2 or 3 times in a week then back to every couple of weeks, very random with no obvious pattern.
When it cuts out there is some loud banging and clanking of the pipes in the airing cupboard and the vent /overflow pipe to the F&E tank gets red hot.
The boiler is in the garage while the hot water tank, motorised valve and pump etc is upstairs in the airing cupboard
Really appreciate any help.
Cut out again on HW this morning after about 15 minutes, not sure if the boiler trips before or after the banging of pipes and venting in the airing cupboard because it's so random. The pump continues after the boiler has tripped.
Unfortunately I am not working at the moment so looking for an 'easy fix' (if only) before calling the cavalry in !

 

[jonnyswamp]

Providing everything is wired correctly, could be a weak/sticking pump
Has the system got a working auto bypass valve

 

[joni os]

Good news: not a faulty boiler. As cylinder stat + MV. renewed and cold feed OK. suspect partial blockage of coil.This can be confirmed by comparing temperature of coil at inlet and outlet when boiler next cuts out, Large difference with outlet temperature near temperature of water in cylinder indicates partial blockage.

 

[nalanosboh]

Thanks

Will check it out and let you you know, what's generally the best way to clear a blockage in the coil ?

 

[Leo21]

Using your phone to call an engineer.

 

[turnpin]

Using your phone to call an engineer.

HaHa....Sharp Leo very sharp nearly lost a mouthful of beer......regards Turnpin:rofl: