Ideal Classic Boiler Cutting In & Out

[Joco]

Hi guys,

Recently moved into a new house and noticed that the boiler is turning off and on quite frequently. Boiler is an Ideal Classic FF260 and is pushing 20 years old.

It seems to be fine for the first 10-15 minutes, then it will cut out for 90 seconds, turn back on for 90 seconds and cut out again (cycle repeats for as long as the heating is on). I'm assuming this isn't how the boiler should operate? Happens when the hot water is on and the central heating is off as well.

Whatever I set the thermostat to doesn't seem to really change anything; tried it at 15 and 22, no difference. Radiators get quite hot but seem to be a bit cooler at the bottom (sludge build up?).

The boiler was serviced in November before I purchased and was passed by a gas safe engineer with no problems. Is this something that would be noticeable during a service and should it have been picked up on? Or is it likely to have just started recently?

Obviously if this is something serious, I'll just get someone in to take a look as I'm not confident/competent enough to prod around with a boiler. But if you have any ideas what it might be or anything to try/test, I'd appreciate your thoughts!

Photo attached of the boiler controls, thanks in advance.

 

[McCombi]

Hi, I would get someone in and before they come explain what is happening, and ask if they know what could be.

If doesn’t happen when first fired up, could have easily been missed by service guy. I don’t personally have boilers running for that long on a service visit but some may.

 

[oldbutnotdead]

Is it zoned or is it off, hot water, hot water plus heat?
Have you tried turning the boiler temperature (rather than the room stat) up. Is the pump actually running? Have you bled the system recently?

 

[shambolic]

Normal operation when up to temperature

 

[Joco]

Hi, I would get someone in and before they come explain what is happening, and ask if they know what could be.

If doesn’t happen when first fired up, could have easily been missed by service guy. I don’t personally have boilers running for that long on a service visit but some may.

Good to know. I didn't want to call up and suggest the bloke might have missed something if a routine service wouldn't have actually taken long enough to notice it. Cheers for the suggestion!

Is it zoned or is it off, hot water, hot water plus heat?
Have you tried turning the boiler temperature (rather than the room stat) up. Is the pump actually running? Have you bled the system recently?

Definitely not zoned, just hot water plus heat as far as I know!
Tried turning it up to 4 or 5 and it stays on longer before cutting in/out, probably around 25 minutes instead of 15 and the radiators get to a higher temperature.
Pump is running, but does seem like it's "ticking" pretty fast?
Bled the radiators I could as a couple are stuck solid and had no air come out any of them so tightened them back up when a few drips of water came out.

Normal operation when up to temperature

That's reassuring to hear! Is there anything in the manual about its operation? I've had a quick skim through but might have missed it. Also, after it's fully heated up and doing it's cycling of turning on and off, if I drop the thermostat down to 16 from 20, shouldn't it stay off until the house naturally cools?

When I previously tried this, it still continued cycling on/off so I'm not convinced the temperature is being controlled accurately – would that point to a fault elsewhere?

Thanks again for the help and replies everyone, much appreciated!

 

[oldbutnotdead]

Sounds like poor flow to me. Pumps don't normally tick, seized bleed valves could indicate corrosion and sludge issues.
Room stat- does the boiler shut down if you turn it all the way down (mine goes to zero).
Are the rooms getting comfortably warm (19 to 21 Deg C)?
Some cycling is normal but every 90 seconds isn't

 

[Joco]

Sounds like poor flow to me. Pumps don't normally tick, seized bleed valves could indicate corrosion and sludge issues.
Room stat- does the boiler shut down if you turn it all the way down (mine goes to zero).
Are the rooms getting comfortably warm (19 to 21 Deg C)?
Some cycling is normal but every 90 seconds isn't

Not sure if the bleed valves are seized up due to the previous owners painting over literally everything or if there's internal corrosion. Tried turning the thermostat all the way to zero when the rads were hot and the boiler was on, didn't do anything, boiler continued to cycle. Also left it at zero and the boiler came on when it was timed to – so it doesn't seem to have any control over temperature!

The rooms seem quite warm, but I'm fairly confident they're not reaching 20, probably somewhere between 16-18°C. Is it worth turning the boiler up to 6 (max?).

 

[oldbutnotdead]

Sounds like the vendors have bodged system to avoid spend before the sale to you.

Get the bleed valves open. You can get spares easily enough if you rag a couple.

Thermostat is either goosed or has been bypassed for some reason. Electrically the room stat sits between the time clock and the boiler and pump.

Running boiler at 6 will delay the cycling but probably not cure your word.

If you're lucky there's a big airlock somewhere causing the flow restriction.

If the pump is mounted with isolating valves it may be worth closing them and dropping the pump out so you can check it properly for function and sludge.

 

[McCombi]

If all hot and you turn boiler stat down to lowest setting and it doesn’t cut out, sounds like faulty thermostat but I would have thought this would make boiler run continuously until separate overheat thermostat kicked in, which would require a manual reset of pushing button on underside of boiler.