Ideal classic boiler starts for a few minutes, then switches off

[sy677]

System was drained and refilled to replace a radiator, but now the boiler won't stay on.

Comes on for a few minutes after following the reset steps in the manual, then switches off.

It's a closed system with expansion tank, no pressure gauge anywhere on the system and old non-digital controls.

The manual suggests an airlock, but all rads and pump have been bled.

Anything else I can try before calling in the professionals?

Boiler model is Ideal Classic SE18 FF with minimal controls (thermostat dial and on/off switch)

 

[ianmcd]

if it is a sealed system with an expansion vessel then you must have a guage somewhere, what colour is the tank you are calling an expansion tank ?

 

[sy677]

White, and there's definitely no pressure gauge anywhere.

The system looks like this:

 

[ianmcd]

That is not a boiler that is an unvented HW cylinder and that expansion vessel is not for your heating system or gas boiler, post a pic of where your boiler is

 

[scoobydo123]

Plastic fitting on the PRV as well although not 100% from the picture if that is what I am seeing cannot see the tundish either

 

[MeldrewsMate]

OP, you may still have a circulation problem.
How did you drain down?
Did you have to isolate mains water to a loft tank, or tie up the ballcock?
Did you simply drain the system, without doing any of the above?
How did you refill the system? Is there a filling procedure, if so what is it?
Answers to the above will help others to properly help to diagnose your next actions.

 

[sy677]

That is not a boiler that is an unvented HW cylinder and that expansion vessel is not for your heating system or gas boiler, post a pic of where your boiler is

I know it's not the boiler, I was showing the expansion vessel. Boiler is just a bog standard boiler in the kitchen:

 

[Andydevon]

If it is anything like my boiler same make and model this fault was down to the Heat exchanger thermister harness failing. Worth checking air locks first as advised above.

 

[sy677]

OP, you may still have a circulation problem.
How did you drain down?
Did you have to isolate mains water to a loft tank, or tie up the ballcock?
Did you simply drain the system, without doing any of the above?
How did you refill the system? Is there a filling procedure, if so what is it?
Answers to the above will help others to properly help to diagnose your next actions.

Drained via a hose attached to lowest rad (no drain off so had to attach to tvr with hose attachment).

Isolated mains water via level next to tank in 1st image above.

No tank in loft.

Refilled lowest rad first, and vented each one in turn up the chain.

 

[sy677]

If it is anything like my boiler same make and model this fault was down to the Heat exchanger thermister harness failing. Worth checking air locks first as advised above.

Thanks. Just to update, it's working again!

I set pump to highest setting and shut down all rads. Vented each one in turn from lowest to highest (as before).

Then vented pump and final vent (left of tank). I had to keep cycling through this venting to get rid of airlock.

Just needed more patience!

Thanks all for your replies.

 

[ianmcd]

you dont have a sealed system you have an open vent system with an unvented hot water cylinder, you have an F&E tank somewhere usually in the loft but have seen them in upstairs cupboards if you had a sealed system then turning the water back on would not have refilled your system