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Posted by HeatPro on August 14, 2006 at 10:23:00:
In Reply to: ideal classic wont light posted by bongobaz on August 14, 2006 at 08:50:50:
Thermocouples get old, replace it.
One important point with a thermocouple is to thread the round button end of the thermocouple into the gas valve with the fingers. If it isn't going into the hole the old one went into easily, then you are trying to fight the threads at an odd angle. Once you get the end to seat with the fingers and gently snug the end with a wrench, tighten it further 1/8th to 1/4 turn. You are just trying to make an electrical connection there; not tighten a pipe. More, and the end can distort and posssibly break the gas valve. The stuff before that is pretty much replacing the thermocouple just as you see the old one that is on it now.
There are two tests to be made. The thermocouple must be tested to assure that when the pilot flame is applied, the thermocouple creates the required millivolts to hold the pilot gas open. This requires a millivolt tester while the flame is applied. There are tools available to do this test from Honeywell at the local supplier.
Once the thermocouple is tested and found to be OK. then the thermocouple is applied to the gas valve. The connection at the gas valve can be tested for continuity to see if it is broken or not using an ohmmeter. If there is continuity, the gas valve should hold open from the thermocouple current.
I would be surprised if thermocouples and gas valves would have problems from the factory. Most suppliers will not accept electrical control parts back, as it is the contractor's responsibility to test that they are receiving good parts. A supplier can not run a business with the expectation that electrical parts will be used as test devices by inexperienced novices until they are successful at performing the most basic of technical repairs.
it may or may not be the thermocouple below is just some of what it could be.
1)Pilot flame
first you need to check that the pilot is on(lit)has it a correct size and flame pattern and is playing the thermocouple in the right place there is a hot and a cold spot on a thermocouple and it will not work if the cold spot is heated or the hot spot cold
2)Thermocouple may not be given right voltage
3)magnetic valve faulty
4)contacts could be dirty stoping voltage
5)interlock like The E.C.O. may have failed or operated
6)pilot flame may blow out from the main burner lighting or turning off (pilot in wrong place)
7,8,9....... and so on and on