Boiler Firing Every 10-15 Seconds

[scotzman]

Hi Folks

A few months ago, my boiler began firing for about 3-5 seconds then recycling, and doing the same continuously. Ultimately, the fan packed in and was replaced with a new one and the system was actually operating a lot better and warmer than previously.

5 days ago, the boiler pretty much refused to fire up. I would light for about 20 seconds and then go off, and could only be forced back on by switching off the system and then turning back on.

It was diagnosed as being the pump at fault and the hot water has reached temp and was turning off the boiler. As per the FAQ's on here, I attempted to try and force the heating on over the weekend whilst awaiting a new pump by turning the hot water on to about 70-80 on the hot water tank, turn down the temp knob on the boiler to one, and put the mid position valve onto manual. This means the boiler tries to heat the water, but never can reach temp due to the boiler temp, and this gives the system time to bring the heating temp up.

This indeed worked and reinforced the suggestion that the pump was at fault.

Ordered a new pump, drained the system yesterday and applied x400 and ran overnight, water was black/murky but no signs of sludge. Drained the system again today, and fitted a Wilo Yonos Pico, added x100 and refilled the system and bled/balance.

Unfortunately it has solved the previous problem, but created a new one.

The boiler (Ideal Classic FF240) is now cycling every 8-10 seconds. There are a couple of the radiators really hot, and some stone cold. There is no pattern, upstairs a couple hot and a couple cold, same downstairs.

All have been bled, and there is no air.

I can get the system to run continually, but it means dumping all the hot water out of the tank and repeating the forced heating measures mentioned above.

Has anyone got any ideas what the problem could be?

One of the things I noticed is that on the controller panel, when I turn on hot water, the controller panel hot water light comes on, the boiler kicks in and a little light appears in the controls pod (underneath the flap at the bottom of the boiler). However, if I turn this off and then turn on the heating, nothing at all happens other than the light appears on the controller panel to say heating has been selected.

Any help, idea's or suggestions would be appreciated.

Regards

Doug

 

[Terrywookfit]

Check the 3 port valve for correct operation.

 

[scotzman]

Hi Terry

Thanks for the reply.

How would I check for correct operation?

I still had it locked on Manual, but just let it out....but the push button on the side has fallen out, so I have no indicator telling me if it is in W, M, H?

Switched system off for 5 minutes, restarted, boiler is now cycling very sporadically, between 3 and 20 seconds, no pattern, so would suggest releasing the 3 port valve has altered something.

Dougie



Thanks

Doug

Untitled

• scotzman
• 8 Jan 2015
• 1

 

[scotzman]

Ok, so shut down the system, ran the hot water away and took the cover off the 3 port valve.

Switched the system back on and selected hot water on the controller....the valve did not move at all..it might have already been on W...no way of telling.

Left it 30 seconds and then selected heating on the controller...the valve still did not move at all.

Its a Drayton mid position valve.

Boiler is still firing randomly between three and twenty seconds.

Dougie

 

[Terrywookfit]

If you leave it set for H/w only, does the boiler fire normally until satisfied?

 

[scotzman]

no, it seems stuck on this cycle of short firing..

 

[Terrywookfit]

But you wrote .....
"I can get the system to run continually, but it means dumping all the hot water out of the tank and repeating the forced heating measures mentioned above".

 

[Terrywookfit]

Do you have mains voltage on the white and orange wires (To neutral not across them) and measured with a meter not a neon or volt stick.

 

[scotzman]

I will get my meter out and check it.

The only way I can get it to fire normally is by turning the temp down on the boiler, and the water temp up on the hot water tank, and putting the 3 port valve into manual mid.

Or, that's how it was working at the weekend. I haven't tried it since I put the new pump on.

 

[scotzman]

Hi

I have mains voltage going into the circuit board on both orange and white, however there is nothing coming off the board to the orange wires feeding the motor.

The orange to the board only read 240v when hot water was selected at the controller so it seems that is working ok.

I switched off hot water and orange went dead and grey was powering up

When hot water was selected I checked all three orange points, two spades on the board and the feed to the motor...nothing reading on those.

Untitled

• scotzman
• 8 Jan 2015
• 1

Untitled

• scotzman
• 8 Jan 2015
• 1

The system is now running with just heating selected, but still cycling firing every 6-10 seconds.

 

[Terrywookfit]

The actuator is fooked!

 

[scotzman]

Thanks Terry, thought that might have been the diagnosis.

Would this be responsible for the short firing in the boiler?

Cheers

Doug

 

[Terrywookfit]

The orange wire in the actuator lead applies voltage to the boiler, which is energised when the white wire opens the valve to heating.
Using the manual lever will not operate the microswitches.
When H/W on is selected, the boiler is energised by the cyl stat.

This is why the boiler works until the cylinder is up to temperature.