gas valve solenoid question

[reghartford]

Just a quick one: I have read that if a multiu funtction gas valve (main solenoid) has power to it (and it doesn't work then it's faulty) - Me I would check the resistance of the coil too - open circuit def. faulty...

I have just heard today that it's best to check across live and neutral at the gas valve main solenoid as just checking the live doesn't rule out a neutral fault.

My point is this - if the coil had open circuit you wouldn 't get any reading across live to neutral at the gas valve surely? am i right or being stupid?!


I just wanted to clear this up with anyone who knows for sure - as I usually test fort power to the solenoid between the live and an earth/neutral as main boiler terminal

 

[durhamgasman]

You would get a voltage reading across live and neutral regardless of whether the coil is open circuit or not.if you test between live and earth,you would read a voltage even if you have lost the neutral,and the valve could be ok

 

[durhamgasman]

that is,if you read between live and neutral and you get mains voltage,or whatever voltage it should be,and the valve does not open,then the valve is faulty,not always open or short circuit,could be the diaphragm inside not lifting,etc

 

[reghartford]

thanks for your reply

if the coil has gone open circuit though - across live and neutral it would not give 240v would it ? as the coil would stop the voltage going back to the neutral?

 

[Boilerman2]

When you test for voltage between a L & N feeding a Solenoid Valve the leads are bridging out the coil so you will get a 230v reading you are not testing the coil to test the coil you have to check the coil using the ohms range (you have already done this as you tell us it is OC!!)

 

[reghartford]

When you test for voltage between a L & N feeding a Solenoid Valve the leads are bridging out the coil so you will get a 230v reading you are not testing the coil to test the coil you have to check the coil using the ohms range (you have already done this as you tell us it is OC!!)

of course!

so what exactly is a NEUTRAL FAULT? is it where a neutral wire/connector is loose??

 

[reghartford]

When you test for voltage between a L & N feeding a Solenoid Valve the leads are bridging out the coil so you will get a 230v reading you are not testing the coil to test the coil you have to check the coil using the ohms range (you have already done this as you tell us it is OC!!)

sorry my mistake - the leads are removed, power off and coil resistance read - one of those days!

 

[Boilerman2]

The easiest way to explain L&N relationship is to put into a plumbing perspective - imagine a flow from a boiler, flowing through a pump around a single radiator and back to the boiler. the pipe work from the boiler, pump and upto the radiator are LIVE. the pipe from the radiator back to the boiler is NEUTRAL. if a a valve is closed anywhere on either the flow or return the circulation of water would stop and the radiator would go cold. it is exactly ther same with an electrical circuit if the live feed gets disconnected from the circuit no water will reach the radiator - or no electricity would reach the coil, if the break or valve was closed on the return - or neutral although energy would be present at the radiator or coil, the energy would be unable to return to the source therefore the radiator or coil would cease.

To test Live test with meter between Live & Earth (230vac)
Then test Neutral with meter between Neutral & Earth (less than 1 vac)
if on testing between Nuetral & Earth you get a reading in excess of 1 volt and most likely a reading approaching 230Vac you have a break in the neutral (the Return pipe)

I hope this explaination makes sense, I have found that this is the easiest way to train heating engineers/plumbers basic electrical circuit skills.

 

[reghartford]

thanks for that explanation

i get it - but just had a long day !

i was always told - if power is going to the solenoid but it's not working then it;s faulty (i always checked solenoid coil too on resistance)!

 

[reghartford]

The easiest way to explain L&N relationship is to put into a plumbing perspective - imagine a flow from a boiler, flowing through a pump around a single radiator and back to the boiler. the pipe work from the boiler, pump and upto the radiator are LIVE. the pipe from the radiator back to the boiler is NEUTRAL. if a a valve is closed anywhere on either the flow or return the circulation of water would stop and the radiator would go cold. it is exactly ther same with an electrical circuit if the live feed gets disconnected from the circuit no water will reach the radiator - or no electricity would reach the coil, if the break or valve was closed on the return - or neutral although energy would be present at the radiator or coil, the energy would be unable to return to the source therefore the radiator or coil would cease.

To test Live test with meter between Live & Earth (230vac)
Then test Neutral with meter between Neutral & Earth (less than 1 vac)
if on testing between Nuetral & Earth you get a reading in excess of 1 volt and most likely a reading approaching 230Vac you have a break in the neutral (the Return pipe)

I hope this explaination makes sense, I have found that this is the easiest way to train heating engineers/plumbers basic electrical circuit skills.

i am sorry if this sounds dumb - it's friday night! how would this be used in practical terms though if you don't mind me asking?

 

[SpecialK]

If coil is open circuit then it doesn't matter about the neutral as its knackered.
If the coil was found to be in tact, then you should meter across it to ensure there is a difference in voltage. If you neutral is down this could be 0v, therefore no PD across the coil, it wont work.
This can also be useful when devices are switched by a print or contact that makes the neutral connection (ie 240v to earth at all times on device).
You could also power down the device, remove the connections to the solenoid and resistance check back to a known working neutral.

HTH.