boiler / central heating problem - main burner weak and cuts out
Im in need of some help in trying to figure out a boiler problem.
Do the following facts and observations point to anything to anyone here. - 3 days ago the boiler (an old fashioned gas fired standard boiler - Stelard Ideal Mexico Super Model CF65 - about 13 years old), pilot light shut off automatically. I relit it, it stayed on, main burner came on. Then after 1 hour the pilot again shut off automatically. I adjusted the pilot screw to increase pilot flame size, and boiler has worked normally for 3 days. - 3 days later, pilot shuts off, I relight it, pilot stays on, main burner comes on, after 1 minute, Main burners AND pilot both go out. If I relight the pilot, it stays lit. NOTE it only goes out 1 minute AFTER main burners come on. Also Note that the main burner flames look fairly weak and the second of the 2 main burners comes on say 20 seconds after the 1st main burner. - I now replace the thermocouple. Makes no difference. Anyhow, the pilot still stays lit as long as main burners dont come on so surely its not the thermocouple. The voltage at the gas valve terminals is 240v ALL the time including when the burners and pilot cut out, so I am assuming there is no problem with the controller or thermostats. I also assume there is no problem with the gas valve as the main burners come on for 1 minute. Note I hear a click from the gas valve when the main burners and pilot shut off automatically after 60 seconds. (Everything is still cold at this point) - I now clean out the 2 main burner jets and pin prick flame holes (There is no dirt I can see) I DIDNT clean the pilot. - Still same problem. - I now notice that when the main burners come on the pilot flame seems to go out and is therefore not covering the thermocouple tip as it does when the main burners are NOT on. - I now adjust the pilot screw again to increase the pilot flame even more. Now when the main burners come on, I can see a pilot flame which does touch the thermocouple tip. Also the main burners and pilot now STAY ON. GREAT - BUT the radiators arent getting hot - only slightly warm, and the pipes coming out of the boiler that should be hot are only warm, even though both main burners are now on and running for 30 minutes. NOTE I can hear and feel that the pump is on and humming. Also NOTE - the main burner flames still look fairly weak to me but Im not too sure what they usually look like. -Bit stumped at this point. Think it could be restricted incoming flue/airways I blow into the main burners from below. The second burner actually goes out now, but I can see a small flame at the bottom of the second burner- below the pin prick flame holes. -Both main burners are now working again last time I looked - but pipes and rads are just luke-warm -Last resort - SOS message on uk-d-i-y Any ideas greatly appreciated (The one comforting thought is the weather forecast over the next few days) SledgeHammerSteve |
boiler / central heating problem - main burner weak and cuts out
Ive just spoke with a rather unhelpful chap on the Caradon Stelrad
Ideal Boilers helpline. But just before he sussed I wasnt a qualified heating engineer and bottled up, he said "Have you checked the burner pressure?" I asked if he meant the gas pressure going into the gas valve, and he said no. Does anyone hear know how and where to check the burner pressure and tell whether its too weak. And if it is what might be the cause. Im now starting to thing this is a weak burner pressure problem. The gas hob appears a bit weak as well. Is this a problem I can get British Gas to check and fix no-charge. Could it be their Gas meter and is testing it and fixing it included in our gas bills. Steve |
boiler / central heating problem - main burner weak and cuts out
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boiler / central heating problem - main burner weak and cuts out
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boiler / central heating problem - main burner weak and cuts out
Thank you very much for that advice Andy.
I will get in touch with Transco asap. Thanks again Steve (I now fully appreciate theres a lot more to fixing boilers than replacing the thermocouple) |
boiler / central heating problem - main burner weak and cuts out
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boiler / central heating problem - main burner weak and cuts out
"Andy Hall" wrote in message ... On 15 Mar 2004 11:33:21 -0800, (SledgehammerSteve) wrote: Thank you very much for that advice Andy. I will get in touch with Transco asap. Thanks again Steve (I now fully appreciate theres a lot more to fixing boilers than replacing the thermocouple) You're welcome. It's not particularly high-tech with boilers like this, but not necessarily obvious either. If this is a "new" problem there is a chance that the gas valve has an inlet filter choked with fine dirt from the pipework. The burner opens up the main gas section which causes a significant pressure loss across the choked filter and limits the amount of gas passing to both main and pilot flames thus the reduced pilot flame is no longer enveloping the thermocouple sufficiently and it cools down then releases the gas valve. Unfortunately the OP doesn't sound sufficiently "competent" to fix the problem and should get a pro in |
boiler / central heating problem - main burner weak and cuts out
On Mon, 15 Mar 2004 21:40:25 +0000 (UTC), "John"
wrote: "Andy Hall" wrote in message .. . On 15 Mar 2004 11:33:21 -0800, (SledgehammerSteve) wrote: Thank you very much for that advice Andy. I will get in touch with Transco asap. Thanks again Steve (I now fully appreciate theres a lot more to fixing boilers than replacing the thermocouple) You're welcome. It's not particularly high-tech with boilers like this, but not necessarily obvious either. If this is a "new" problem there is a chance that the gas valve has an inlet filter choked with fine dirt from the pipework. Possible, but he says that the hob is a bit poor as well, which tends to point more to something on the supply side. The burner opens up the main gas section which causes a significant pressure loss across the choked filter and limits the amount of gas passing to both main and pilot flames thus the reduced pilot flame is no longer enveloping the thermocouple sufficiently and it cools down then releases the gas valve. Unfortunately the OP doesn't sound sufficiently "competent" to fix the problem and should get a pro in ..andy To email, substitute .nospam with .gl |
boiler / central heating problem - main burner weak and cuts out
5 minutes after reading Andy's first message, I rank Transco (9.00pm).
2 hours later one of their guys was round checking the gas pressure at the meter - It turned out to be 12mb (should have been 20mb) so youre dead right- there is a supply side problem. 1 hour later there were 3 guys digging up the supply pipe in the front garden. (past midnight now). When they cut through the supply pipe there was virtually no hiss coming out at all. They then stuck a flexible rod down the supply pipe towards the road. It hit a blockage where it joins in the main supply that runs under the pavement. Now its 1:00am in morning - said they'd be back next morning to dig up the pavement. End of story. Thanks very much for everyones help, advice and suggestions. -I must remember to think of the system as a whole, and not concentrate on most obviously affected part. And the real cause of a problem your looking at can be miles away. (priceless lesson) Thanks again - (hope someone finds this thread useful in future and saves themselves a sunday taking the boiler burner to bits) Steve |
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