IDEAL ICOS HE24 intermittent LF code

[NotBuyingIdeal]

Hi All

I know I know ... another HE24 LF code problem. Fix is replace boiler ;-)
My problem is slightly different to other posts I've been reading in that the boiler works fine for 95% of the time. It will often go a few days then we get the LF code. We hit reset and it always always re-lights. It will LF at all times of the day or night ( when running ;-) . No real pattern to it.

My plumber has replaced most of the bits on the boiler and every time we think it's sorted but it then returns.

We've even setup a CCTV camera to film the bolier which is in the attic ! That way we can easily check if it's LF'ing.
We can also play back the point when the problem occurs. This is the sequence of events
'0' when no demand.
'c' and solid white LED - heating on/water heating.
then it will go wrong........
'c' and flashing white LED for a few minutes
'LF' and flashing white LED for a few minutes
'LF' and no LED until reset where boiler will relight and run fine.

Happy to post it happening on youtube if that will help. There's no sound but it DOESN'T appear to be trying to relight 3 times etc.

it's a heat only boiler, its on the attic level and heats that floor and the floor below ( 6 rads / 3 towel rails in total ) and 2 x 120L hot water tanks. Open vented system. External pump.

So what's been replaced / checked?
Condensate trap is clear
Condensate pipework is clear ( we actually ran boiler into a bucket for a few days )
Flame sensor
Flame sensor cable ( insulation had broken down - we through this was the smoking gun )
Spark generator and spark electrode
Fan
Insulation in combustion chamber ( was in a bad way )
Earth pins in combustion chamber
External pump ( this seemed to be working fine anyway ) - Circulation seems good.
Sump cleaned multiple times
New PCB multiple times
Gasket set
We've had it power flushed. We had a long period after the flush/drain/refill where the system was stable. System treated with X100/200.
The flush/drain/refill also cured it of a moaning noise it use to make.

Which areas haven't we looked at ?
Gas Pressure - we actually have another boiler downstairs in the basement. For a while we suspected the other boiler was robbing the ideal of gas pressure but after changing the timing controls to make sure they weren't trying to fire up at the same time. LF problem doesn't seem to co-inside with the use of other gas appliances in the house.

We also had alot of new houses built near by. Could the pressure to our house be an issue ?

Gas Valve - Plumber happy to swap this but he's saying probably isn't the problem as it's working most of the time.

Are there any other ideas out there that we could consider ? or is it simply that the boiler just flames-out now and again because it's just sh*t ?

Thanks in advance.

 

[Deleted member 120897]

Is L-F, or L-F. ? I believe the dot has significance to a specific fault, however it may be cheaper to either replace the boiler, or get a fixed price repair from Ideal?

 

[NotBuyingIdeal]

Hi. don't think there's a dot ( or comma etc ) after the F

I did read about that fixed price repair from ideal and tried to find out about it on their web site. I'm not sure they still doing it. We think Boiler was installed in 2006 by previous owners so also maybe too old.

 

[NotBuyingIdeal]

Hi. don't think there's a dot ( or comma etc ) after the F

Not seeing anything in the ideal docs about 2 types of LF code. Tell me more !

I did read about that fixed price repair from ideal and tried to find out about it on their web site. I'm not sure they still doing it? We think Boiler was installed in 2006 by previous owners so also maybe too old.

 

[ShaunCorbs]

New boiler ?

 

[exedon2]

As above why are you throwing money at a 16 year old boiler?
Replace.

 

[NotBuyingIdeal]

Hi Shaun
I know- said at the start ... Fix is replace boiler ;-)
Frustrating that it works 95% of the time and always re-lights on reset. It's on right now - everything's toastie.

Something else I found in the manual is the requirement for an auto bypass valve. We don't have one and everything has TRVs. Could this cause an LF ?

Saying that the system is a bit unconventional.
looking at the boiler flow, before we get to the 2 port value for the rads circuit we have;
a 28mm loop which runs to the hot water tanks. Each tank has it's own 2 port valve
a 22mm circuit which runs to 2 towel rails downstairs ( with TRVs )

so if the water and/or heating are calling for heat there's quite alot of pipework which is always open. Maybe that's the reason we don't have an auto bypass ? Could lack of one cause LF ? Certainly overheat or pump burnout but LF. I'm not seeing it.

As an experiment i've removed TRV heads from the towel rails. They will stay fully open. See what happens.

 

[NotBuyingIdeal]

As above why are you throwing money at a 16 year old boiler?
Replace.

Not as straight forward as cost is very high. Had a quote to do it. >5k. Boiler is in the attic so they want to raise a scaffold outside. Also head height is very limited so would be a very tricky install. They want to install a new gas supply in at least 28mm pipe as they reckon the 22mm isn't big enough. This would be from the meter in the basement up 4 floors up through wall papered rooms etc. Would cause a total mess. ( thinking another 1.5k for making good ) The 22mm main has worked fine for 16 ( well 14 ) years ! Not sure if that is actually part of the problem. Back to getting the gas pressure tested ;-)

like I say - it works fine 95% of the time. We just have to watch CCTV and hit reset every couple of days to fix it. IMHO we're not quite at the replace the boiler stage.

 

[ShaunCorbs]

Tbh I would get other quotes also depending on boiler type you might not need to upgrade the gas but this can be tested on the old boiler

 

[Mikesin]

Hi,did you fix intermitent L-F ? I have same. Having watched behaviour I am thinking of replacing overheat thermostat..