Discuss Thermecon s90/120 lockout fault in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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Oddbod

Hi,

I'm not a heating engineer and I have no intention of touching our boiler, but I really could do with some friendly advice regarding a weird fault.

The boiler is an 8-year old ThermeconS90/120. Burner is an Ecoflam Minor 4. Nozzle is a 1.10/60 Location is a dry outhouse.

When cold the boiler will fire with a flame established, but almost immediately locks out. Press the lockout button and the boiler fires and behaves normally. The fault only seems to occur when firing from cold. Any residual heat and things work fine.

What follows is the history. I'm not being critical of any of the engineers actions – the detail is just there 'cos I don't know what matters and what doesn’t.

The boiler was working perfectly until it was serviced. The nozzle was replaced however the port normally used for the air supply probe could not be used as something was “spinning around” (I assume the plug screw or connector thread stripped?). The engineer drilled a hole in the flue but then found he didn't have the right sensor equipment so didn't set up the air supply. There was no black smoke from the flue so it was deemed OK. He didn’t seal the hole in the flue.
Following the service there was a tiny continual oil leak from a connection - a drip an hour kind of thing.

After a week the fault started to occur and the engineer came back, cleaned the nozzle (it being sooted up) and set the combustion mixture using the hole in the flue for the sensor. It took a long time and the air setting ended up much higher than the manufacturers suggested range (and much higher from what it was when the boiler was working before the service)

It worked fine for a week and then the fault started to reoccur. The engineer stopped taking my calls.

I found a second engineer – really nice bloke, well recommended and clearly knew oil boilers.

The second engineer performed another service. Fixed the oil drip, cleaned out the baffles which were full of red powder and set up the combustion. Didn't change the nozzle.

A week later the fault reoccurred.

The engineer returned and replaced the nozzle. (On the grounds that the first one may have been faulty since it was the only thing replaced since the boiler had worked). Set up the combustion again, ending up with the air setting much nearer to the recommended value this time.

This morning the fault reoccured.

Before I ring him again I'm just wondering if anyone has any great ideas we could check out. This has all the makings of a “just throw bits at it 'till it works” saga. Which is fine if that's all we can do, but I'd feel daft if I hadn't at least asked if this problem rings a bell with someone.

Following are some additional points.They may or may not be correct.

The boiler was working fine until the service, so something happened at that point. The first engineer inadvertently damaged or changed something or otherwise provoked the fault – photocell, wire, control board? (I'm not having a pop here, I know that coincidence happens and that the slightest disturbance can exacerbate an existing fault. That said I do now wonder how experienced the first engineer actually was.)

According to the second engineer the photocell is clean and seems to be in the right place.

The oil tank is pretty full. It was not topped up, the supplier was not changed etc. The oil pressure and filter seem fine.

The solenoid seems to be OK (it seems they usually fail when hot not cold).

(See, I now know far more about oil boilers than I ever thought I would!)

So I have two questions. Is anyone thinking “Oh yeah, that's obviously.......”? Secondly would it be worth replacing the whole Ecoflam burner. I believe it's a couple of hundred pounds and, provided the fault is somewhere in the existing burner, it wouldn't take too many more visits for that to become the cheapest option – let alone the most convenient one!

Thanks for any advice.

Oddbod
 
You say the filters seem fine, are they? is it gravity fed? Is there plenty of flow flowing to the burner on it's own accord?
 
Hi Croppie,

Whenever it has been off for 7 or 8 hours. So mornings and evenings both. Its Ok if it's only been 2 or three hours.
 
Hi MarkOil,

As far as we can tell. The boiler has a pump but the tank is higher than the boiler and when it runs out (ahem first winter - 3 years ago) it self primes fine.

You thinking that the pump might be "lazy" and needs a couple of goes? The odd thing is that the flame establishes but then the lock out occurs. It doesn't seem like oil starvation.
 
If cold start ONLY it fails after flame ignited, then it is your engineers fault, - simple as that. Get an engineer to make sure burner is set correct. Did you get the air adjustment that was broken fixed?
How can you be sure it is now occasionally failing only on cold start? It could go to lock out previous night unknown to you.
 
Sorry chaps, still on pre-mod - so replies need to await approval. (And thanks to the mods for taking time out to do so.)
 
Hi Best,

We've set the burner a total of three times, by two different engineers. It runs fine for a few days and then the fault re-occurs. No re the adjustment, neither engineer seems to think it matters and they both used the hole drilled in the flue. Whats broken is whatever the engineer would normally remove to stick the probe in.

Once started it seems to run fine until the time clock shuts it off. I can hear it fairly well. It never seems to lock out during an "on" period. That said I will check tonight & make sure. Fair point.
 
Likely this is the problem, - burner is Over aired,
-engineers are Under experienced.
 
^^^^ I concur.

If they left a print out of your flue readings can you tell us what the O2, CO2, CO and flue temps are?
 
Smoke pump used first & properly would sort it, if oil pressure etc all set.
I don't like 60 degree nozzles also.
 
Agree with all that has been said
also could be filter and after it is primed after first lockout will carry on all day. Just done one today same problem
 
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Thanks for all the advice.

Hi Best, I confirmed that it locks out on start not the evening before. 60degree is the recommendation in the manual, but we don't know what the first, working nozzle was. Stupidly I threw it away. What would you try?

Hi Croppie, No I don't have a print out. Are you saying I should have had one? If so I will ask next time

Hi SimonG, seemed to be up to temp. The boiler thermostat was on max and it had been burning constantly for a good 10 mins by the end of the setup.

The consensus here it that it is over-aired. So on the basis that a consensus is a consensus for a good reason that sounds like the place to look.

What puzzles me is how two engineers could set it up wrong three times. It's not like it's an unusual procedure. Could something be drifting or moving? An air leak somewhere? The sensor is being placed in the flue rather than close to the burner. Could that throw the figures out?

Kimbo, we might as well try replacing the filter too this time. It can't do any harm.

Guys, I really do appreciate the help!

Oddbod
 
Filters are checked as part of a service, so is analysis of the flue gases to give you flue temp, xs air, o2, Co ppm, CO2, efficiency etc, of which all would be filled out on a cd/11 form:

[DLMURL]http://www.ossw.co.uk/wp-content/uploads/2011/10/Commissioning_form_CD11_web1.jpg[/DLMURL]

From this they would probably diagnose the problem straight away (if they understand the readings)
From their analyser they should also be able to print a hard copy of the readings from your boiler for them and you to keep.
If they haven't done these then they haven't serviced your boiler or correctly or looked into the fault properly in my eyes, or OFTEC or other engineers I wouldn't of thought.

Maybe get 50% off all that you have paid so far for half a job done?? Just a thought.
 
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Thanks MarkOil. He definitely used the gas analyser but didn't leave me with a printout. I'm an engineer myself - albeit an R&D one - so we were chatting about what he was doing and about the mechanics of boilers as he was setting it up. He was focused on juggling the CO and C02 - it was very sensitive. If he was faking it was a good act!

More worryingly I can't find either the engineer or firm on the Oftec registered list, despite the Oftec logo being on the website. At least he's not on the list of the 4(!) engineers who have had their membership revoked. Think I'll give Oftec a ring - make sure I'm not misreading their membership list or something. If He's legit we'll have another go. If not I'll do what I should have done in the first place and find someone who is on the Oftec list. Live and learn I guess.

Thanks
 
1st engineer sounds a real cowboy, didnt clean baffles, cleaned a nozzle (!), got FGA wrong.

Drilling the flue is fine if the test point is seized or unserviceable but should stick a bolt in it afterwards.

As above, over aired can knock the flame off but also worth checking the ht leads arn't obscuring the photocell, that can create intermittent faults as can worn ht leads, maybe the cold mornings are a red herring.
 
Thermecon 90/120s are temperamental beasts at the best of times. To get any decent figures, stick in an 80° EH nozzle at minimum rating. It is very hard, if not impossible to get good figures with a 60° nozzle as the flame hits the back of the combustion chamber.

Is the flue conventional or balanced? A long balanced flue on these can cause problems.

Other possible causes for this type of intermittent failure are the motor capacitor (but this will have been tested during the service) the motor itself, or a tight point on the oil pump.
 
Ignore the nozzle recommended in the manaul, give Thermecon a call and ask them what they're service engineer would fit, its probably what you threw away.
 
Have had same sporadic lockout problem with our Thermecon 90/120 for 9 years !!! No-one has resolved it. Thermecon tech man today suggested get our engineer to check vacuum in flue more carefully. If more than 1-4mm on water gauge may pull jet away from spark and doesn't light. We are going to check.
 
If that's the case then the electrodes have been positioned wrong. Or turn the burner upside down. Done that on a couple of old units.
 
Bit of a thread resurrection!

Well we had one more go and couldn't find the fault so in the end I build an auto-lockout-reset gadget out of a linear actuator and a little micro-controller. It tries three resets before giving up.

It does look a little bit like the sort of thing you'd find in one of those shops in Soho, but hey it works.

The bad (good?) news is that the boiler has gradually started to lockout more often - to the point where it now does it regularly. I'm hoping this means that we have a better chance of finding the problem.

So any oil boiler engineer out there in the Reading/Newbury/Basingstoke fancy a challenge? (Or a laugh at a slow moving electric ***** - no, not me, the reset mechanism!). Full fee and as much tea/coffee/biscuits as you want. Located Tadley.
 
My breath has never been so baited, how did this lock out problem work out?
 
e0dcf22f040c06bec3944b73f716372f.jpg

James did tell me, think it was a blocked filter. This is the device :)
 
Wow, that's a great invention. Better get a patent on that quick smart :aureola:
 
Yep, James is still on the case! A new motor to be fitted and all sorts of oil unions to be tightened.

It's not yet 100% reliable and the auto reset device still kicks in from time to time, but it is soooo much better.

If we can get another year or two from it we'll ask James to fit something decent.

I'll post a picture of the other end of the reset device, with the electronics, tonight.

Thanks all
 
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Here is photo of the other end
Therm reset.jpg

I had the bits lying around, but it would probably cost about £80 if I had to buy it all. It took about3 hours to make. The reset arm is a linear actuator from a lawnmower cutting deck height adjuster. It gets connected to 12v DC by the electronics. It moves forwards or backwards depending on the polarity.


The electronic gubbins is based on an Arduino micro controller. The black tube contains a neon indicator connected in parallel to the lock out light. (It’s 240v but very low current so not dangerous). The other end of the tube contains a5v light sensor that tells the micro controller if the lockout is on or off. The blue relays are connected as an H-bridge (basically a polarity flipper) and allow the micro controller to drive the actuator in either director. The little display just reports what the thing is up to – number of retrys, time before the next attempt etc etc. Finally the whole thing is driven by an old laptop power supply. The actuator needs about 1A at 12v.


When the software detects a lockout it waits 60 seconds and pushes the reset button. It tries this three times and then waits for an hour before trying another three times.It’ll do this forever if the reset light stays on. If it fails to start from cold three goes are usually enough. If it fails when hot an hour is usually enough to let it cool down to the point where it will restart.


I know it’s something Heath Robinson would be proud of, and I’m sure Thermecon would be having kittens if they knew about it, but until Bunker recommended James it was this or freeze!


Hopefully I’ll never have to make aMkII.


In the unlikely event that anyone is daft enough to want to know any more, ask away.
 

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Here is photo of the other end
View attachment 21231

I had the bits lying around, but it would probably cost about £80 if I had to buy it all. It took about3 hours to make. The reset arm is a linear actuator from a lawnmower cutting deck height adjuster. It gets connected to 12v DC by the electronics. It moves forwards or backwards depending on the polarity.


The electronic gubbins is based on an Arduino micro controller. The black tube contains a neon indicator connected in parallel to the lock out light. (It’s 240v but very low current so not dangerous). The other end of the tube contains a5v light sensor that tells the micro controller if the lockout is on or off. The blue relays are connected as an H-bridge (basically a polarity flipper) and allow the micro controller to drive the actuator in either director. The little display just reports what the thing is up to – number of retrys, time before the next attempt etc etc. Finally the whole thing is driven by an old laptop power supply. The actuator needs about 1A at 12v.


When the software detects a lockout it waits 60 seconds and pushes the reset button. It tries this three times and then waits for an hour before trying another three times.It’ll do this forever if the reset light stays on. If it fails to start from cold three goes are usually enough. If it fails when hot an hour is usually enough to let it cool down to the point where it will restart.


I know it’s something Heath Robinson would be proud of, and I’m sure Thermecon would be having kittens if they knew about it, but until Bunker recommended James it was this or freeze!


Hopefully I’ll never have to make aMkII.


In the unlikely event that anyone is daft enough to want to know any more, ask away.

Would it not of been better to spend the 3 hours finding and repairing the fault? I'm kind of guessing that is also at your home and not in someone's utility for them to trip over lol.
 
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