Grant External combi oil 21e burner lockout.

You have two separate and unconnected problems to consider:
1. Do you have a pressure problem? If so, is it in the boiler or the system? Pressure up your system cold to 1.25 bar. Make sure it has stabilised, then turn the isolating valves on the boiler. Leave for an hour or so and check the gauge. If it has fallen, you have a boiler problem. Open up the isolating valves and see what happens to the gauge. If it falls, you have a leak in the heating circuit. If before opening the valves you have lost pressure, and your system is sound, you should notice the pressure gauge rise.
2. Burner lockout is indicative of flame failure and is caused by lack of fuel, faulty flame sensing with a faulty cell or obstructed view, or a faulty control unit.

Treat each problem separately. Trying to correct them together will be distracting.
 
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It was leaking out via the PRV when the failed expansion vessel was still fitted. I asked for the PRV to be replaced at the same time as the new vessel just to be sure. It was neant to be a a good thing, bit of belt and braces just to make sure the boiler was 100%! The burner led flash thing has only started since.

PCB as you said is the next thing we'll try our luck with.
 
Hi Oilhead, thanks for the suggestions. We did have a pressure problem, that's what kicked off this whole saga! Happily that now appears ok, after the replacement of the PRV and vessel. Since then we've been chasing what I believe is only a burner issue, which currently seems to be up with the control panel.

The Riello itself is running seemingly fine, no more lockouts and firing up perfectly. From 4an until 10an this moring it was heating fine, then as I noticed the radiators cooling I went back outside and sure enough the burner led light was flashing. I have just stood outside and while watch it, turned the thermostat on/off about 20 times with varying lengths of time between each switch. It worked fine each time and the radiators are still toasty warm now.

I would stay out and just sit in front of it and watch (so I can see at which point it is doing it) but the rain is torrential at the moment and I don't have an umbrella!

I am not sure quite what to call the issue, a burner lockout is to me when the burners own controller has locked it out. The issue right now seems to be with the Grant (PCB temperature?) controller.
 
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WBRacing,
Let me know if you ever work out what the problem with your boiler lockout is please.

I have exactly the same issue, our outside wall hanging grant boiler keeps intermittently locking out at start up but fires up normally. I have had various parts changed all of which make it work for at most 3 months.

The boiler was fitted in June 2013 and worked perfectly fine for the first two years only so of course it's out of warranty. It started playing up in October 2015 and hasn't been right since.

Grant actually came and fitted a whole new burner for me at the end of November and today we have another lockout so it lasted just over 2 months this time.

They checked the oil line fully too with a pressure guage and also the oil filter.

I am at my wits end now and fed up of having to wake up and listen out for boiler then go outside (in whatever weather) and reset the thing.

Anyway rant over but do keep me posted.
 
Oilbiffin, I am not sure if you are aiming your question at me or the OP. Wouldn't want to highjack his post...
 
I had a prob with boiler intermitatly locking out so I checked everything I could I suspected fuel so I left my oil gauge on and I found that the stem valve was sticking every so often not always but very inermitantly so I changed the oil pump no more lockouts.Bob
 
Thanks oilboffin, hope this is the answer for wbracing.

Alas not for me as oil pump was changed as part of the whole new burner.
 
SOLVED.

Ashtara - I really hope that this is of help to you but I fear it won't be.

At the weekend despite the weather I camped out in front of the boiler and watched it. Exciting stuff...

As the property neared the set temperature (I think I mentioned it has a smart thermostat) the burner shut off in anticipation of reaching the set temp. A few minutes later the boiler went a bit crazy, turning on, off, on, off etc.. repeatedly and erratically every few seconds. As the burner motor spun up and down, it sounded the same as when you sit in a car randomly blipping the throttle. Eventually, the boiler simply locked itself out.

It was clear to me from this that it was receiving an irregular demand signal, I could hear the boilers relay clicking away in time with the demand signal post purge so figured that it could only be the thermostat doing this, basically being indecisive as to whether or not it should be turning the heating on.

I replaced the Netatmo smart thermostat with a £16 Drayton mechanical model from Screwfix and since then all has been running perfectly, even if not so efficiently.

My sincere thanks to you Andy, Oilhead and Bob for taking the time to try and help. Hugely appreciated.

Good luck with yours Ashtara, the best advice I can give based on this experience is to sit down and simply watch the boiler and see/hear exactly what it was doing.
 
Hi Ashtara,
Did you solve your problem with burner lockout on the 21e.?
I have this problem and I am at my wits end wondering what to check next (Respect to WBRacing, Andy, Oilhead & Bob)
 
What have you checked so far?
Does the boiler run for a while then lock out? If so, for how long?
Does it lock out immediately all the time or is it intermittent?
 
Hi Oilhead,
Thanks for getting back to me after such a long gap.

The boiler is just over two years old and in the last few months has been erratic with its lockouts.
Last three weeks its been working fine, but this week, nothing but lockouts. This has been the pattern over the last few months.
The boiler runs for about 6 mins then locks out. I reset it from the reset button on the burner which show red.
At the start of all of this I had the boiler serviced to a good standard and got all of the certs and readings. It was fine for a time and then lockouts.
There is no air in the system, the PRV works, runs at 1.5 bar and the lockouts are not thermal (I think)
Today I changed the PCB thinking that its erraticism may be down to electronics. I also blead the oil line(took off 5 litres), cleaned out the oil filter(was clean), blead the oil from entry point into the burner. Currently appears to be ok ... but i am watching it.
 
Burner lockouts are down entirely to flame sensing. This can be a faulty photocell, (or dirty one), a faulty control box, a faulty ignition transformer, which may be part of the control box, incorrectly set or broken electrodes, a faulty nozzle, Lack of fuel, or airlocked fuel line or blocked filters.
How long is it since the service?
 
Thanks for the 'heads up'
The boiler was well serviced by a trusted, meticulous boilerman 21Aug2020 when it was working consistently.
He was very through. Even pointed out that the condense pipe was not run in inch and a half!
I feel confident that we would have picked up faults with the photocell, control box and electrodes.

My attention was/is drawn to the fuel delivery - as you pointed out.
Yesterday I robustly bled the fuel supply and was attentive to all things fuel.
One of my discoveries was a shard of copper passing through the considerable amount of oil that I was drawing off.
The shard may have been the result of me, some months ago, re-jointing the union with the tank and de-burring the inner part of the pipe.

This may be the solution to my problem - the shard restricting the flow of oil - as,
- I did this work several months ago when I think my 21e problems first started. (Difficult to tell as the demand for boiler was less in the summer)
- Could account for the erratic nature of the lockouts - periods of working/periods of not working
- The patterns of lockouts - 5/6 minutes of firing then lockout, then able to fire again after a rest (empty fuel line/then full fuel line??)

The current status now after clearing out the fuel delivery system is that the 21e appears to be workings as it should and firing normally.
HOWEVER the cover is still off and I am never far away - constantly checking and observing with everything crossed .
Will keep you informed (and everyone else if following) on progress. Thank you for sharing your thoughts.
 
D

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