Coventional boiler won't fire up - pilot ok.

MiserlyMartin · 4 December 2006 at 1:22AM

I have a Potterton Flamingo 50 boiler. Today it just stopped firing up, the pilot is fine. I reset it. The thermocouple for the pilot I replaced only a month ago so thats ok. It doesn't matter where I set the thermostat, which clicks as normal.

This is where my knowledge is patchy, but I presume that theres another thermocouple connected to the boiler 'tank' body which senses when the gas valve should switch off. Question is - is this crucial for the valve to switch ON? Are these thermocouples a common fault in the same way they are for a pilot not lighting?

What I am basically asking is should I replace the thermocouple for the valve before looking at a new valve, or am I totally off track here?

Any help appreciated - its bloody cold in here!

BTW: pump, timer control unit and room thermostats are ok, plus no hot water obviously

david29dpo · 4 December 2006 at 8:43AM

when you turn the boiler on, can you hear the main burner valve click? if so, the valve could be sticking shut. if not, its not getting power to open it. the "thermocouple" on the tank body is the thermostat sensor which turns the main gas valve on and off when the water temp as been reached.

espresso · 4 December 2006 at 8:06PM

You could eliminate the boiler thermostat by temporarily removing the two wires from the rear and connecting them together. The thermostat is in series with the live feed to the gas control valve.

Just because you replaced the thermocouple last month doesn't not mean that this is not faulty, can you measure any output voltage from it? Has the nut loosened?

advent1122 · 4 December 2006 at 8:21PM

Gas + Electricity = Get a man in.

I wouldn't "tinker" if you do not know what you are doing.

MiserlyMartin · 5 December 2006 at 7:49AM

Thanks for your replies. When I replaced the thermocouple last month the pilot didn't light. I replaced the thermocouple and pilot was fine, boiler ran fine until now. This is a new problem as the pilot is on ok. No I can't hear the loud click that you get when the boiler normally fires up, I presume from the valve.

I will try eliminating the thermostat.

david29dpo · 5 December 2006 at 7:52AM

yes, try that. but if it works get a new stat quick!

MiserlyMartin · 5 December 2006 at 7:56PM

I have some good news! Boiler is fixed! Life is a learning experience and I hope my tale may help anyone else here with Boiler problems.

I removed the mains cover on the gas valve to first check the input voltage, ie to see if the thermostat was switching ok. Before i could even do that, lo and behold I saw that the Neutral wire had broken its crimp connector in half and was hanging there. Having no suitable crimp connectors or crimp tool in the house, plus the fact the screw on the terminal was seized, I decided to strip the wire bare and solder the wire to the terminal.

Covers all back on and valve obviously now turning on gas fine now it has mains from the thermostat back.

So this is the 3rd time I've saved a gas man coming out.

First time I had no heating the water pump went, so I replaced that myself. I even had to drain the whole system because the isolating valves wouldn't shut off - big job.

Second time last month the pilot went out and would not light, I replaced the thermocouple.

And this time a dodgy wire to the gas valve! How could this have happened? I wonder sometimes if boiler servicing men do things like this to generate themselves more income years down the line.

I must have saved a bob or two. So moneysavers don't be put off having a go yourself, ignore those posters who say 'oooh get a man in'. It could be a very obvious or simple problem. I should add that I am an electronics engineer so I do know a bit about fixing things, but not boilers.

But please be safe and isolate the mains first and don't play with the gas bits. Electrical parts ok to replace yourself.

Incidentally, had the valve been faulty would I be allowed to replace it or is that a CORGI mans job?

david29dpo · 5 December 2006 at 8:14PM

good for you! i am also !!!!ed off with people who call a man in to change a fuse and tell others to do the same. IQs seem to be dropping by the day! not sure about the valve being a corgi man job, but i will find out.

espresso · 5 December 2006 at 8:34PM

Well done for doing it yourself and thanks for reporting back.

MiserlyMartin wrote:

I must have saved a bob or two. So moneysavers don't be put off having a go yourself, ignore those posters who say 'oooh get a man in'. It could be a very obvious or simple problem. I should add that I am an electronics engineer so I do know a bit about fixing things, but not boilers.

I totally agree, those posters should not assume that everyone is as incapable as they are.

:rolleyes:

the_gasman_2 · 9 December 2006 at 6:41PM

MiserlyMartin wrote:

Incidentally, had the valve been faulty would I be allowed to replace it or is that a CORGI mans job?

Congratulations on your simple repair.
If only everyone was able to diagnose simple faults like this it would mean i finished work at a reasonable time to see my family.

In response to your above post about changing the valve?
Yes you would have to have someone corgi registered to change the gas valve...
I don't make the rules just adhere to them and not all of us in this industry are crooks out to rip you off.
The reason they have to be registered is because you have to break into the gas supply to change the valve.
I am not here to tell you you are incapable as i know lots of people work in engineering or have a high standard of diy knowledge. Its purely a safety factor and the correct procedure of working with the gas supply. I wouldn't try to redesign windows xp cause i have a little knowledge of computers. We all have our niche markets thats how we earn a living.
I have to say though, "A little knowledge can be dangerous". Thats from experience of visiting people who have tried to repair a boiler themself...
I do think we gas men get a lot of bad press which is caused by these so callled cowboys who rip people off. Sadly as corgi engineers we cannot report these scamsters. Its upto the public. (YOU OUT THERE) Corgi say it looks like we are trying to poach customers by complaining. Trust me, i would love to shop some local plumbers/ handymen. I work for a reputable company who is fair and doesn't rip people off. The downside to this is we have to turn people away as we are always very busy.
I do hope you can all find a local heating engineer who is fair honest and reasonably priced.
Failing that ring rogue traders for advice and shop these criminals.

good luck

david29dpo · 10 December 2006 at 7:55AM

well said. i have found an excellent corgi guy when i needed i gas hob connected. prices ranged from £40- £150! if any one needs him in the DY area, let me know.

Coventional boiler won't fire up - pilot ok.

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