No hot water. Boiler faults, banging the lot! Idel Icos HE15

Hi there,

We have had plumbing problems of various sorts for a few years.

We have had various people in, and more recently I've had by brother in who is Corgi registered and quite a well regarded plumber locally, but none of them seem to be able to fix things.

Boiler is an Ideal Icos HE15

Anyway, here is what is happening, I think there may be 2 faults, no idea if they are related- they don't seem to be.

First Fault
Firstly, with just the heating on, everything runs pretty well for 20-40 mins. Then the boiler switches off showing an LF code. Resetting it then causes LF again and again. Sometimes if you switch the system off for a while it will light again.
My brother cleaned the condense trap and pipe but it didn't fix the fault. I believe his next move is the gas valve when he gets time. Is there anything else he should be looking at before this or while doing the job?

Second fault
The second fault (which as I say may or may not be related to the first) occurs when the hot water is on.

With just the HW on, the boiler lights, heats water for maybe 20-30 seconds, then there is banging noises from the boiler and it shuts down. When I say shuts down, I mean that it stays on, the "C" remains on the display which I think indicates it is still getting a call from the heating, but the light starts flashing (it's solid when lit).

Additionally, if I listen to the pump when the HW is on, it sounds a little louder, as if under strain. Also, there is a bleed valve near the pump and cylinder (pipe from pump goes up into the electric valve, the valve is at the top of the pipe that comes out of the valve on the HW side, a few inches above where it enters the cylinder.) Anyway, I can keep bleeding air off here all day, it just keep filling. Sometimes, I bleed the air off and water comes out, sometimes the air just runs out (water head too low??)

With the heating and water on, the rads fill up with air while the boiler is running. That is, I can walk around bleeding the rads, by the time I have done the last one, the first one needs bleeding again.
THIS ONLY HAPPENS WHEN THE HOT WATER IS ON. Rads stay 100% full when just the heating is running.

Anyone any ideas? I'm at the end of my rag, my brother can only get down every week or so, he does things which seem to fix the problem but then a few hours after he has gone they will start again.

Cheers,
Dave

PIPEWORK SIZE ?

the ideal icos and Evo boilers require 28mm pipework on all boilers over 60.000 btu but i have found the 15's also like it if the pipework isn't straight for about 1 metre from boiler

There is something which is not right about what you are saying!

With a pressurised system it cannot just be full of air or even allow air to enter.

You cannot go round bleeding rads unless you keep on increasing the pressure! What pressure are you running it at?

I am sorry but it seems as if your brother has no experience of LF fault finding on these boilers! Its unlikely the gas valve is the cause and there are a lot of things to be checked first.

You say that so many people have been round but it seems to me that none of them have been in any way investigated any of the possible causes.

The obvious solution is to call Ideal as their engineers have lots of spares to throw at it and can connect their laptop and see the fault record history.

Tony

Thanks for the answers. Pipework size is 22mm

My brother also said on the phone yesterday that it was not possible that they keep filling with air, but that is what is happening! Works fine with just CH on, but as soon HW is put on, it as if something is forcing loads of air into the system.

I'm not a plumber, so sorry what I'm saying might not make sense, but the pump sounded as though it was pumping air with the water, kind of like the noise a fish tank pump makes when it's bubbling air into the water. Only makes this noise when both CH and HW are on.

My brother doesn't have much experience with this LF fault by his own admission. He does have a spare one of these boilers though which was working when he took it out of his house so he has plenty of spares. I was hoping someone could suggest what the next move would be (if not gas valve). Bearing in mind it is able to light, but after a while it goes off and then won't relight.

My worry with calling Ideal was that they would charge a fortune and that it might not be a fault in the boiler but an external thing. I guess that might be what I have to do ultimately though.

Sorry, not sure what pressure it's at. My brother is going to have another look today so if I remember I'll ask him what pressure.

Agile said:

With a pressurised system it cannot just be full of air or even allow air to enter.

Click to expand...

Forgive me if I'm wrong, but I didn't see the OP mention anything about it being a sealed system.

DaveSk, do you have a small header tank for the heating, or do you have a pressure gauge and braided filling loop?

Thats a very good point and one that I had overlooked as I so rarely ever see a condensing boiler on an open vented system.

It could also explain the fault too.

The LF fault can also be as a result of an overheat which disconnects the gas supply and creates a flame failure LF code. Thats probably whats happening.

The air in the system will either be an unfilled F&E tank or a pipework layout fault or a blocked feed pipe.

Explain to your brother that its been suggested that its an open vented system and that air is getting into the system and causing an overheat problem.

Those clues will probably enable him to solve your problem as it does not need specific knowledge of your boiler model.

Dont forget to tell us what is the outcome.

Tony

mogget said:

DaveSk, do you have a small header tank for the heating, or do you have a pressure gauge and braided filling loop?

Click to expand...

To be honest, I'm not 100% on that! I have never seen a pressure gauge or anything braided, although there is no header tank in the loft - I think it's part of the cylinder.

Just looked it the cylinder and it says "Vented cylinder/combination tank"

So I assume that it's not pressurised?

Overheat usually results in L:A or H:9

L:F is the evergreen ignition failure. Get him to remove the condensate trap and sump, cleaning both thoroughly as a starting point.

Often it will be the same fault with the boiler, but 'appears't o be different on HW and CH.

Basics first. Out of all the faults I've had on Ideals and there have been loads, the gas valve is one of the rarest

Thanks gas4you, he's already cleaned the trap (is the sump part of this?)

It was full of crap and everything came on so he went off thinking the fault was fixed. A few hours later it was back to its old tricks.

One of the problems is that when he comes round, everything is working, or it's not behaving in the way it was a few hours ago, so it's hard to diagnose the fault.

This morning it has been off for about 3 hours now and I can't get it to light on HW or CH....

I'll see what he says when he comes round and report back, hopefully telling you all that it is fixed, but more likely that it's still up the pole....

The sump plate is the plate held on with 3 screws at the bottom of the HE.

This can get very clogged with the aluminimum of your HE that the condensate has eaten away through normal use. It needs to be especially clean on the right hand side, where the flue is connected.

You also need the ignition and flame detection electrodes checked.

If I come across an awkward one of these that is clean and appears otherwise ok, I have found, more often than not, the flame detection electrode has been faulty and it all works ok after replacement.

But then I am fortunate to carry these as spares all the time

Thanks! At least I now have a few things for him to check when he comes round.

I'll update when he's been.

All Icos he boilers can be fitted to an open system as seems the case on here. It does sound like a circulation problem. Get your brother to check flow and return temps at the boiler on hw only and on ch. If these are too high (over 20) then you have a circulation problem.
As for the LF code this can be on overheat as if the boiler overheats 3 times on the same on period it will kill power to gas valve. So next on period no gas then LF.
Also get him to remove sump as suggested then pour water down this which should clear instantly if not and it backs up you could have a partially choked condense pipe further down, or an airlocked condense which would require an airbreak to be fitted. Have seen this loads, The installer checks condense is clear by blowing down it connects back up and thinks its ok after an hour or two the boiler has backed up again as its airlocked not blocked.

shambolic said:

As for the LF code this can be on overheat as if the boiler overheats 3 times on the same on period it will kill power to gas valve. So next on period no gas then LF.

Click to expand...

Thanks for that, you learn something new every day.

The problem as I can see it for us mortals is that without the software on our laptops as you have, shambo, how are we to know the L:F has been caused by these 3 overheats

L:F seems to cover so many faults it is (almost) meaningless sometimes

Just an update for anyone interested.

My brother came over but didn't have long sadly. We cleaned the sump, it did have deposits in it, although they were not enough to cause the sump to fill. I hadn't read this so we didn't try topping up with water to see how well it ran away, although the sump was pretty dry inside and didn't look like it had been backed up. Will review this again if we need to though.

He found a couple of problems with the cylinder. The ball cock was either the wrong type, or the arm had been bent. This is causing the water level to not get high enough. I might have this next bit wrong, but I think he said that this was where the air was getting into the system. I think he said that water was boiling in the boiler and steam coming up the pipe and out in to the top part of the cylinder. As the water level is below the fill pipe it's not automatically filling. As I say I might have got that bit wrong!

Additionally he suspects an airlock on the HW side (in the coil in the cylinder) and is coming back tomorrow to get the airlock out.

All that sounded right to me. The only thing that is troubling me now is that after he had gone I managed to get the heating running for half an hour or so but eventually it went to LF. I'd assumed that because the fault was on the HW side I could run the heating with no problem. Ah, well I guess we'll see tomorrow what's going on with it.

Thanks again for the replies. I'll let you know what happens.