Worcester 350 locks out in morning only?

Follow up in 2008! We have had the meter checked and eventually got a quote from BG to put a new boiler in. During the survey we found that the gas feed pipe would be far too small for a modern boiler and, at 15mm for a considerable length, may be too small for the 35 KW Worcester. It is possible that there just isn't enough gas flow first thing in the morning. I was told that modern boilers can tolerate only a very small pressure drop and for the length of gas pipe we have would need a 28mm diameter supply pipe.
We are still living with the Worcester as the quote for a new boiler was quite surprising to say the least.

Tony Bardwell
February 2008

Hi, follow up from earlier comments:- The boiler got to the stage where you could find it "locked up" , go through a re-set (switch power off and on) and then only half of the burner would light. This could be done several times before the burner started to light right across.
I had a good look at the burner assembly (switched everything of first of course) and found that there are some small wire mesh pieces about two thirds of the way along and on top of each burner. I would suspect that these are put there specifically to promote the flames on the first lit burner to spread to the next one. It would appear that with the fan assembly drawing air up between each burner pair that each flow of gas from a burner is effectively isolated from the next one. The small pieces of mesh act as turbulence generators or maybe just spread the gas/ flame a little so that the next burner ignites.
Any way I used a stiff paint brush and vacuum cleaner to get as much dirt and carbon out of the meshes and the tops of the burners expecially the area under each small mesh.
This has made a marked improvement with only one early morning lighting failure in two weeks (it still runs all day on CH and HW OK once it starts in the morning). The next step would probably be a new burner assembly if I get fed up with having to re-set every so often but these are well over ninety quid to buy.
Anyone else seen this problem?

Tony Bardwell
May 2007

Hi, follow up from previous:- The boiler has worked fine for about a week then did not start one morning. Sure enough it had been "locked out" for about 30 minutes. I went to the kitchen and turned on the gas stove and there was plenty of gas.
I went back to the boiler and pulled the front cover off and then switched the power off and back on. The boiler went through it's start up, the burner lit but only half of it had flames. It shut down pretty quickly (only a few seconds) presumably because the flame sensor was not being heated. I turned the power off and on twice more to observe that the burner only lit on the half with the spark igniter. After that the burner lit right across every time. The boiler has started every morning since.
I am going to have a look at the burner and see if there is anything physical or obvious that could cause this. However I did see one other "posting " that mentioned that the burner could fail to light right across.
It may be that the electronics are not allowing enough time for the burner to light completely and effectively shutting down too early. Any ideas?

Thanks Tony

Tony Bardwell
April 2007

Hi Paul thanks for reminding me that a fault can lie outside of the boiler itself! (you do tend to get focused on the machine itself).
I looked at the regulator and it looks fairly new so may or may not be a problem. If it "locks out" again I will try the gas cooker to see if the gas is flowing or not.
However I have found this week (by accident) that when the boiler was not lit (locked out) that I can make it work by turning on the hot water tap thus demanding hot water. The boiler will light up for HW and then run the CH side fine.
It therefore seems to be not a "lock out" as described in the manual but something else that happens now and again. As I said I have checked out all of the obvious things that supply the logic input to the starting routine. Any clues gratefully received!.
Tony

Tony Bardwell
April 2007

sometimes early morning lockouts are nothing to do with the boiler at all. If you have a very old govenor on you gas meter they can stick shut overnight. have a look and if it looks ancient ask transo to change it for you

Paul the gas man
March 2007