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Michael, Customer Service
Category: Appliance
Satisfied Customers: 9568
Experience:  I have been an appliance repair tech for over 30 years and will help you solve your problems.
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We have a Worcester Bosch Greenstar 24i Condensing Boiler (not

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We have a Worcester Bosch Greenstar 24i Condensing Boiler (not combi). Nothing is switched on but the boiler keeps firing up for a few minutes.
Hi, I am Tech Michael an expert in this field and I will be assisting you today. I am a Master Technician that's dedicated to giving you the best Answer possible.If you are new to the site, this is briefly how it works:1. We may need some back and forth to exchange information (if needed) and there is no extra cost for replying.2. I will give you the best possible Answer for your problem without the ability of actually being present with you.The better you describe the problem, the quicker I can help ;-)3. Remember to leave a Positive Rating ,it doesn't cost anything additional to rate kindly;-)I am only credited for my time and expertise if you rate kindly.How old is your Greenstar 24i ?Also do you use this for hot awter as well as heat?Thank youTech Michael
Customer: replied 2 years ago.
The boiler is just less than 5 years old. Yes, we do use it for hot water as well as heating.
Hi thanks for that I was out due to an emergency. Sorry for the delay ;-)Does it come on as if its just re heating the water and then cuts off by itself? And, does it seem to be working well in all other respects, hot water and heat?That's all I will need to knwo and I will have an answer for you , just need to be sure ;-)Thank youTech Michael
Customer: replied 2 years ago.
Yes to both of those questions. It's almost as if the frost stat has gone mad - and it thinks it's really cold!
Hi yes, the most likely cause of the problem is a bad thermostat.What you need to do to be sure, is to disconnect the t-Stat and let me know if it still keeps coming on like it is? It will fire normally to keep the water in the boiler hot, but if it seems to be turning on more than normal let me know.Thermostats aren't very expensive, I woudl simply replace the one you have its easy and I will help. You can find one at your local hardware store or plumbing supply company.Or if you need I can supply a site online for that, please let me know, also I will help you replace the t-stat its really easy;-)In any case, I will stick with you until this is complete.Please rate my service thus far.Also it is the only way I am credited for my time and expertise with you.Once you rate, I will be notified and will add your question to my priority list so you can reach me anytime until this problem is solved.Then you can reach me by simply replying to this message anytime.Thank you and have a great day!Tech Michael
Customer: replied 2 years ago.
Not completely sure I understand. If nothing is switched on, why should the boiler be trying to keep anything hot? Normally it only fires up when heating and/or water are switched on and it is keeping things at the set temperature. This I completely understand. But this is happening when NOTHING is switched on, i.e. there is no reason for the boiler to be firing up at all.
Hi, if you mean no power is applied to the system then no the boiler would not fire. But if there is power the boiler will fire every-time it reads the temp dropping below a certain preset value usually 140 deg F.It does this so the water will be hot on demand;-)Please remember to rate kindly I will still be here to assist you further if you have any further questions on this;-)Thank youSincerelyTech Michael
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Customer: replied 2 years ago.
Okay thank you. It is now 3 am and the boiler has just fired up again!! In the morning I will attempt to disconnect the thermostat and see what happens. Can you tell me how to do this please - I don't know where to begin.
Hi, sure,When you remove the Tstat from the wall, you can remove the wires from the Tstat, but make a note where the wires went maybe take a pic or two before disconnecting anything;-)But, I dont think this is being caused by the T stat.It could be, under rare circumstances but I dont think its the reason for your issue.Thanks Tech Mike,please keep me informed.
Customer: replied 2 years ago.
I contacted Worcester Bosch today just to check whether or not the boiler was still in warranty. Unfortunately, it isn't - however, they were certain that it would not be the boiler that is causing the problem but the programming device, as they say it is this that controls when the boiler fires up. I have established that when the heating is on because it is programmed to be on, the room thermostat works perfectly well - it is only when the programmer is off that the boiler fires up periodically, regardless of what the room thermostat is set to.
Customer: replied 2 years ago.
Sorry to say your answer wasn't helpful - we have established it isn't the thermostat - as I told you on 24th March - but you haven't come back to us since. We have a plumber coming in tomorrow.