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May 18, 2009
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Heating Engineer (Has GSR)
cannot get pilot too stay on,not thermocouple,i have cleaned gas pipe lines, when i press to get pilot lit , it sparks and lights but i have to hold grey button in the minute i let go the pilot goes off,it's as if the thermocouple is not sending a charge to hold valve open, but when i check the thermocouple it work fine, any ideas
 
power up the boiler,check theres 240v at the gas valve,if thermos been replaced can only be the gas valve but if you dont find 240v then test incoming power and thermostat
 
power up the boiler,check theres 240v at the gas valve,if thermos been replaced can only be the gas valve but if you dont find 240v then test incoming power and thermostat

would having 240v have any bearing on the pilot.
 
yes gas valve gubbins fubbard,not seeing thermocouple this is a simple fault if you have replaced thermo and have a good pilot flame and have 240v at gasvalve the valves knackerd simples
 
gas valve desrob.

It's a pain when they hold until you service the boiler then can't get it to re-lite! Explaining that one to the customer takes some tact!
 
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gas valves the problem if pilot fine & t/c renewed, but pilot goes out after releasing.
 
depending on the type of honeywell valve, you may get away with just changing the magnetic valve that the t/couple goes into. cheaper than a new valve and alot easier to change.
 
yes gas valve gubbins fubbard,not seeing thermocouple this is a simple fault if you have replaced thermo and have a good pilot flame and have 240v at gasvalve the valves knackerd simples
240 v or no volts the pilot should still light and stay in mains voltage has no bearing
 
depending on the type of honeywell valve, you may get away with just changing the magnetic valve that the t/couple goes into. cheaper than a new valve and alot easier to change.
Are thermo electric devices available to buy for the V4600 valves? Never new was serviceable. It is almost certainly this that is faulty, going buy desrob's description. Pilot good, new thermocouple, just sounds like the thermo electric device not energizing. Just changed the whole valve whenever came across the problem myself.
 
Desrob
Did you actually change the thermocouple or just test it? Never trust a test 100%. If the pilot flame is strong and it is playing on the thermocouple and the connection is tight then it is the thermocouple. It can't be anything else. It will stay alight regardless of having power to the valve. A universal will do it for £1.50.
If the solenoid was gone the pilot would stay alight but the burner would not ignite. The valves themselves are very reliable and very seldom need changed.

Steve
You can still buy solenoids for v4600's and v8600's. Part V404A is the 240v and V804A is the 24v.
I usually strip the best ones off a boiler i swap (somebody has always fitted a new valve) and offer them as a previously used part with a 3 month guarantee (you'll never need to go back).
Simple job, 4 screws and the wires. Don't even need to turn the gas off.
 
The problem is one of three things.

1. Faulty thermocouple

2.Weak pilot light.

3.Faulty FFD in gas valve.

Try a couple of thermocouples,as tamz says,a new one can be faulty sometimes,and a £1.50 thermocouple is worth trying before a £100 gas valve.
 
I forgot the mark 4 had a pilot aeration tube. It it is one of those check the tube is clear and it is sitting in the right position.
 

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