problem with Ideal mini HE boiler... please help

I was hoping someone might be able to advise on a problem we are having with our boiler.
We have an Ideal mini HE boiler fitted a couple of months ago, which was meant o be an end to our heating problems, but no such luck!

Hot water is fine and sometimes the heating works, but often when we switch the heating on the boiler makes all the right sounds like it is firing up, but it doesn’t appear to ignite, (I don’t see a flame through the viewing hole, which I do see if I turn a hot tap on). Sometimes it does come on, but then it switches itself off again after about 10 seconds.

We have radiator thermostats, which I have made sure are all open, and we have a control box on the wall next to the boiler which has on/once/twice/off – and this is ‘on’.

We have had the plumber that fitted the boiler come back, he couldn’t find the fault (because of course it was fine when he was here), but I think he replaced the thermostat in case it was that – but later we had the same problems of no heat in the radiators at all, so we had an engineer come from Ideal. He wasn’t sure what was wrong, but he tightened a loose washer on the gas outlet in case it was that (as he said the flame was starting high above the outlet, which may have made the safety sensor switch the boiler off??)

That seemed ok for a day or so, but we’re still without heat coming out our radiators on a reliable basis. This is very confusing as it does sometimes work fine…but other times I’m sat in the cold with a noisy boiler, but no heat! Any advise would be great, as it seems no-one we’ve called out knows what is wrong…

thank you

if ideals own engineer can't fix it whilst stood in front of it, I doubt we'll have much luck from behind a keyboard. There is however a scottish chap who sometimes comes on here who happens to be a lead engineer for Ideals, so if he sees your post he may be able to get something sorted for you and give Ideals some desperately needed good PR in the process!

btw as a guess I would say the CH min modulation rate was too low, but I would have expected the Ideal engineer to have checked that.

dhw flow switch made (possibly with crud in dhw shuttle?)

do these ones have the red light on the flow switch?

if red light is on with no dhw demand, boiler will fire and heat plate heat ex, and sit quite contently firing on/off

thank you both for very quick replies.
I should have said there are no red lights; there are 3 green lights, 2 of which flash (as the manual says they should) when the heating is 'on' even when it is not actually working...

BTW - I have no knowledge of boilers so I was hoping that by consulting such a large knowledge base that someone could suggest things for an engineer to look at if we call another one out. i know it might annoy an expert if i say 'have you looked at x/y/z?'. but after the last guy didnt seem to know how to fix it i figured it cant do any harm to have things to suggest!

thanks

agile may be able to help on this as it is the same boiler as his beloved biasi

it is a fairly reasonable boiler usually the biggest problem is having a numpty attend the last call, get them back and back again until it is sorted.

hopefully you will get it sorted eventually. although i hate Ideal with a passion, their engineers (the ones i have met) have been very knowledgeable about the boilers.

as a further update which might help with any more suggestions people might have, I have been watching it for the last hour or so (when the heating is emant to be on) and the heating DID come on for about 10 minutes, but then it went off suddenly and i noticed that the temperature guage was high (80). After running the hot water tap for a while the temp went back down to about 60, and when i turned the tap off the burner stayed on but temp crept back up to 80 and it switched off again... apologies if this is blindingly obvious to everyone else, but does that mean it shutting off as its overheating? if so ...why is it overheating after 10 minutes of heat?
thanks

coldhands said:

I have been watching it for the last hour or so

Click to expand...

probably nearly as good as the telly!! PMSL

poor circulation is the most likely cause.

- yes i suppose that did sound very sad didnt it!
I work from home, so not having central heating when i need it turns me into the kind of person who watches boilers rather than tv!

when you say bad circulation, does that mean we need to have the system flushed? when the old boiler was breaking down all the time we were told we needed a powerflush, but our landlord decided it wasnt necessary...

Sounds like boiler is getting to temp and cutting off due to no circulation in the flow and return to rads.
If the pump or main heat exchanger was faulty then it would be failing on water too, so we can discount that.
Next I would be looking at changing the diverter valve cartridge in case its sticking(after putting heating on while manually pushing spindle) as it could be firing heat round the internal bypass if faulty.

I would also check isolating valves are fully open.

And a last resort (i did this last week on a mini with the same fault although this was 3 years old and fault developed I suspected a zone valve left in system that had failed) I cut the flow ansd return to the boiler under floor and fitted a 3 meter loop of 22mm and made sure it heated ok and my temperature difference at flow and return was 15deg.

Try from cold put boiler on and see how hot the left hand pipe is compared to the right hand (both 22mm) If you have thermometers then fine shouldnt really be anymore than 20deg at most.
if there is a massive differential then defo blockage on pipeework to rads.
Hope this helps
And puts us in a better light.
Where are you in the country?

Also make sure you have 1 radiator without a TRV on it as well.

I will assume that this is the latest boiler known as Mk II in the Biasi version with a plastic LH block with bits unseen previously.

The diverter valve is obviously not moving as expected.

The first thing is to see what the boiler THINKS its doing. The front lights:-


Flashes together for heating ???

OR

Flashes alternately for hot water ???

IF its flashing together and not heating the rads then the diverter valve is not moving correctly, either its not told to or is not doing what its told!

The pin is PRESSED for hot WATER on this model!

So the obvious thing is to remove the motor and ensure the pin comes out and then expect to see the rads getting hot.

Another potential problem is that the PCB had several operational modes which have to be set in software pushes on the boiler controls. One fault mode enables the diverter valve to move to the opposite position than expected.

They are easy you fix for someone who is prepared to understand how boilers work.

Tony

see i told you agile would probably know!!

Well I dont actually know whats wrong in this particular case, I only know what MIGHT be wrong.

To take the diagnosis further we need further information and the results of simple tests.

Tony