Ideal Mini HE C28 boiler banging and not working properly

[a904lea]

The boiler was already in the house when I bought it last year, but it's been there since the property was built in 2003. After about 30 mins of use, the boiler makes an alarming clanking and banging noise, and then settles down - only to repeat the cycle again 15 mins later. Also, when the DHW is on without CH, I find I can have a shower without a problem, but once I turn off the flow of hot water, the boiler will not reignite automatically if I run the shower (or a hot tap) again. The boiler makes a low humming noise at this time. I have found, by trial and error, that if I switch the central heating on, the boiler will reignite and I can restore the DHW.

I've taken the outer casing off the boiler and can see that someone has wrapped red tape around the part of the boiler that is banging (on the left hand side). I am a bit worried in case it's some sort of 'pop off' safety valve that's being held closed. I've posted a photo in the album 'Ideal Mini'

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• a904lea
• 8 Feb 2011
• 1

Boiler pressure is constant at 0.7bar, which the manual says is correct.

Can anyone tell what the problem and whether it's a DIY repair? Is the red tape a safety hazard? Any help would be gratefully received.

 

[Agile]

It looks to me as if its been bodged and that may well mean dangerous, either for you or for the boiler.

Can you post a close up of the part of the boiler on the left with proper lighting.

Tony

 

[plummerman]

Looking at that picture someones either lost the retaining pin from pump proving switch or broke the bottom of the micro switch housing to try and bring the mircoswitch closer to the proving pin. You really need to get someone to come and check the boiler, banging is more often than not due to temp/flow issues and possibly the reason the pump proving switch is mackled like that cause pump is running slow

 

[a904lea]

Can you post a close up of the part of the boiler on the left with proper lighting.

My daughter is living in the house at the moment. I've asked her to take some photos, which I'll post here as soon as I get them.

 

[a904lea]

Hope these photos help: -

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• a904lea
• 10 Feb 2011
• 1

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• a904lea
• 10 Feb 2011
• 1

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• a904lea
• 10 Feb 2011
• 1

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• a904lea
• 10 Feb 2011
• 1

I've also uploaded a short video clip here http://www.twosoups.com/Ideal_Mini_HE_C28_boiler.mpg

My daughter also says that although the radiators warm up, the house doesn't get very warm because the boiler seems to cut out too quickly and then takes a while to restart, even when the room thermostat is turned up high. She also added that the bathroom radiator is cold at the top, but even though she's bled it several times, it always stops 'hissing' air before any water appears at the bleed nipple.

During my trawling of the internet, I have found many instances of these boilers running at 1 to 1.5 bar. Is the 0.7 bar it is currently set at too low, even though that is what the manual suggests? Would it do any harm to increase the pressure?

Would it be worth changing the main flow control valve diaphragm and switch as a starting point as it looks like it's been bodged in the past and is the part that moves around when the boiler is banging? What about changing the DHW flow control valve at the same time as a precaution?

 

[Agile]

0.7 Bar is insufficient to force water to the top of the system. It should be set to 1.5 Bar cold.

The switch needs to be fitted with the correct clip. That will probably then display the other symptoms or not work at all.

The system is probably very dirty and the boiler partially blocked.

Tony

 

[a904lea]

I will be visiting my daughter at the weekend, so will increase the system pressure when I am there. I am pretty sure the filling loop is below the sink, but I've never looked, so I'll keep my fingers crossed.

Do you think it makes sense to replace the CH flow switch and diaphragm, or just the switch while I am there? I can order the parts today and get them delivered tomorrow.

If the system is dirty and the boiler partly blocked as you suggest, would flushing cure the problem or would parts need to be replaced? Is flushing something that I can do myself, or will it require a professional?

I realise that remote fault diganosis isn't an exact science, but your help is very much appreciated.

 

[Agile]

All you seem to need is the clip!

But the switch box might be broken.

I dont recommend replacing anything unless there is a clear requirement to do it. I go to quite a few failed DIY attempts where all they have done is fit expensive parts which were not required and add faults in the process.

Its not possible to correctly diagnose boiler faults without testing and inspecting.

Anyone who tried to tell you otherwise is as much use as a fortune teller!

Tony

 

[a904lea]

Thanks for the advice!

I'll increase the pressure and maybe remove the tape to see why it's there. I can always tape it back up again afterwards.

My next question is, what's the best way of finding a 'good' boiler specialist in Swansea?

 

[a904lea]

Are there any air bleed points on the boiler or do I just need to make sure that every radiator is bled?

 

[Agile]

The boiler has an auto bleed valve behind the pump.

You can loosen the air cap and then close it until it JUST becomes tight.

Unless there is a problem my advice is dont fix it. Faults caused after bleeding rads makes up about 5% of calls I receive.

Your wish to touch/change everything makes me think you are just going to add to your problems.

Diagnose first, fix afterwards!

Of course you could always emulate some cowboy plumbers and start by changing the PCB and charging your daughter twice the cost !

Tony

 

[a904lea]

I shall touch nothing - except topping up the system pressure!

 

[a904lea]

I shall touch nothing - except topping up the system pressure!

Just a follow up to say that topping up the pressure and bleeding the radiators has cured the boiler banging and clanking. The DHW flow switch is still temperamental, so I may consider replacing it at some point in the future. My daughter is chuffed to bits as her house now gets warm when the central heating is on

Thanks for the replies - and the sound advice not to blindly replace parts!