Ideal Classic cuts in and out

[desparado]

I have a 2 week old Ideal Classic HE boiler on an old open vented indirect system. From cold the Boiler will run for approx 10 mins then shut off. then cutting in and out at approx 1 min intervals until the CH and/or HW temp is met by the thermostats. No undue noise or airlocks aparant in rads. Hot water and all rads get hot. Tried turning the pump up, it resulted with water pumped through the vent pipe and out the overflow. Tried bleeding flow and return pipes with no air apparant.
Any advice appriciated, Thanks

 

[Agile]

What did the installer say when you called him back to it?

Based on what you have said it would appear that the flow rate through the boiler is too low and the boiler stat is switching it off. Blockages ???

OR

The boiler is not modulating down ( or is not designed to modulate ??? ).

If it is designed to modulate and it is not doing so then I would expect the gas valve is not properly set up.

Tony

 

[desparado]

installer will not be avaliable for 2 weeks (holiday) im not sure if it is designed to modulate. If the fault requires a heating technician i will have to wait. Thought it might be something I could handle. Thanks

 

[Agile]

Its not designed to modulate sso its operating quite correctly. If you turn the boiler stat down a little then it will stay on rather longer and be more efficient.

The original Ideal Classic was a very reliable design and many were sold. They achieved a reputation with users for amazing reliability.

My experience is only based on the ones I am called to fix. I find they have all overheated the plastic parts which have become brittle and fall apart when I touch them. They may be fine if not touched but I expect to be able to remove spade connectors from the fan without it breaking.

They have just used the old cast iron heat exchanger and added a second condensing HE to achieve the increased efficiency and capitalise on the good reputation of the model name.

Gas engineers will be surprised to know that they ask in their delightfully clear MI for a MINIMUM gas pressure at the inlet of 20 mB. The tolerances which the gas shippers work to will not always achieve that as it could go down to 18 mB and still be within tolerance.

This boiler is very tolerant but its a theoretical point!

Tony

 

[desparado]

Thanks tony, going with the flow problem theory. I tried mains pressure through the header tank feed to try to clear a possible air lock. As a result the boiler seems to stay on longer before the boiler stat cuts in. Turning the boiler stat down slightly makes the boiler cut out earlier.

Cheers Alun

 

[ChrisR]

Tried turning the pump up, it resulted with water pumped through the vent pipe and out the overflow.

Alarm bells ringing.

Either you have a blockage, or poor pipework layout.
DO a search on "Pumping over"