Zone valve problem boiler stays on

[Inverness]

hi guys, I'm only a forth year apprentice so he nice.lol
My mates mums was complaining that her berating won't go off even though the time clock was off. I thought zone valve must be sticking so I replaced the head and it was going off and on like it should.
But a few days later she said it's playing up and doing the same as before.
My conclusion is I should of changed the who body of the zone valve. It must be sticking in the open position and not closing when called.

It's an old stelrad boiler. You have to start by manually light the pilot and hold the gas in until the thermo couplin is hot and opens up the gas valve. I have a lack of understanding about this boiler I'm I correct in saying when the heating and hot water is satisfied the boiler will go to pilot light mode it won't completely switch off? As if it did you won't need to manually light it over and over again. my question is how does this type of boiler completely switch off ?. And how would it re light again?
With your expert advise would be so appreciated as I'm hoping to fix it this Friday.

 

[ShaunCorbs]

Easy way to test see if your still getting voltage on the call / orange wire if it's a 2 port

 

[Inverness]

Easy way to test see if your still getting voltage on the call / orange wire if it's a 2 port

There must be voltage because it did work when I replaced the head. But now I think its sticking in the open position. How does this type of boiler switch off when the programmer is off. Does it remain with a small pilot light until heating is called then it fires up? Cause when it’s on the heating is off and the pilot is on the zone valve must be stuck and letting heat through the radiators when it’s off at the programmer. Thanks Shaun once again

 

[ShaunCorbs]

Yes permanent pilot if it's got a thermo couple