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Tim JA
Tim JA, Customer Service
Category: Appliance
Satisfied Customers: 2331
Experience:  Owner at Self-employed
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My w- heatslave 18/25 shows lockout light after 5-10 minutes

Customer Question

JA: Hi. How can I help?
Customer: My w-B heatslave 18/25 shows lockout light after 5-10 minutes of operation.
JA: What's the brand and model of your lighting? How old is it?
Customer: Green star Heatslave 18/25
JA: How long has this been going on with your lighting? What have you tried so far?
Customer: 10+ years old
JA: Anything else we should know to help you best?
Customer: 1. Burner halts after 5-10 minutes from cold. Less time from warm/hot. 2. disabling DHW, THEN CH From external programmer produces same results 3. water pressure good 1 o 2.5 bars
Submitted: 1 year ago.
Category: Appliance
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call.
Customer: replied 1 year ago.
Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 year ago.
Based on auto-response, (lighting?), I need to make it clear that this is a Worcester-Bosch Greenstar Heatslave 18/25 Oil fired central heating and water Boiler. Need an expert W-B qualified engineer. Thanks!
Customer: replied 1 year ago.
Unit was second-hand, bought 2 years ago and in need of repair. I replaced the controller and wired up an external (Drayton) programmer. Plumber fixed the water valve. It has worked fine until this week. The lock-out light comes on after 5-10 minutes from cold and shorter periods thereafter. Suspected a Thermostat as I switched off the DHW & CH from the Drayton in turn and still had the problem, suggesting the issue is not those thermostats. Reached the end of my limited knowledge of the unit. Help! ��
Customer: replied 1 year ago.
I can called on my landline if you can’t get me on the mobile: 01978 790 386
Expert:  Virtual-mod replied 1 year ago.

I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you!
Customer: replied 1 year ago.
As it’s the weekend, I don’t really expect an early reply, so keep on trying!
Expert:  Tim JA replied 1 year ago.

Good morning

I don't claim to be a W-B Heatslave expert, but I'm a heating engineer and have worked on oil boilers so rather than leave your question unanswered I'll offer what thoughts I have.

With intermittent lockout I would check the basics:

1. Fuel starvation;
2. Dirty or failing optical sensor;
3. Earth terminals loose or corroded.

The third of those is the quickest and cleanest task, so I would start with that.

The optical sensor is pretty easy to clean and/or swap out, if you haven't done that yet.

With the fuel line, I would check and clear any external filter (between tank and boiler), and blow air back all the way from the fire check valve so that it's bubbling into the tank. If necessary, rig up an adapter made from duct tape and use a bicycle pump to blow back - anything will do.

Customer: replied 1 year ago.
Thanks, Tim.
I have the Instruction manual for the Heatslave 18/25 and, although I'm not a plumber, I was, before retiring, an electronics reseach engineer then lecturer. (I only mention that to prove that I can read circuit diagrams and generally fix stuff, but I follow the rule that when in doubt, ask a real expert !)So I've considered the three items you've kindly provided and:
1. The lock-out consistantly comes into play about 4-6 minutes from cold down to 30 seconds when fully warmed up. So I suspect a thermostat.
2. If it was a dirty photcell, my guess is that it wouldn't shut off in relation to the heat. But I'm only guessing.3. If the earth terminals were loose or corroded, I suspect the problem would again not relate to the heat in a consistant manner, but I could be wrong.
I appreciate you coming back to me on this. If you had particular experience of the W-B 18/25, I'd appreciate a pointer to in the direction of the thermostats. As mentioned in my original text, I tried programmatically to close off the DHW and CH thermostats individually and the problem continued, so it might one of the other two, but then it might be the burner itself [back to the photocell?] I'll check.
Appreciate your support.
with regards,
Expert:  Tim JA replied 1 year ago.

My background is also in electronics, but this isn't a competition of academic qualifications.

If there's a heating demand then the boiler will go into the ignition sequence. Lockout results from a big range of possible causes, mostly related to fuel or electrode problems that lead to flame failure (or detection thereof).

You're tending to dismiss my recommended checks on the basis that you can eliminate those possible causes by hypothesis; I think that's fallacious. I feel that you want the fault to be in one of the thermostats, but I don't concur with your analysis. If you're wrong about the earthing, then all bets are off, hence that aspect needs to be physically checked. If you're not prepared to check the basics that I would be checking if called out, then I can't help you.

Customer: replied 1 year ago.
Apologise if I seemed to be comparing qualifications... not what I wanted to imply... Just that I can do a bit of investigation . You're right, of course, I am dismissing the possibilities, so I'll check thoose first.
thanks, Tim.
... and you are right too about my bias towards the thermostats! ... I'll do proper checks first :)
Expert:  oleksandrav-mod replied 1 year ago.
It seems the professional has left this conversation. This happens occasionally, and it's usually because the professional thinks that someone else might be a better match for your question. I've been working hard to find a new professional to assist you with your question, but sometimes finding the right professional can take a little longer than expected.
I wonder whether you're OK with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.
Thank you!
Customer: replied 1 year ago.
Please close this question. Whilst your service is a good model, the person who first responded wasn't a good fit as I needed a Worcester-Bosch certified professional. This person who responded merely repeated a small section of the trouble shooting manual for the Boiler, (which I'd already read). I decided to contact W-B and they pointed me at a local certified installer who fixed the problem in about 10 minutes.
Expert:  Tim JA replied 1 year ago.

... as indeed I probably would have done if visiting.