This is kind of an update to a problem I have had for a couple of years now but is still not fixed despite a lot of money and effort being applied.
My system is a fairly simple Y-plan system with HW tank in the airing cupboard.
To try and keep this simple the problem I have is the fuse blows in the fused spur supply to the heating system - which is mounted to the wall at the side of the programmer. The RCD does not trip but the 3A fuse does blow. This problem started a long time ago and came on slowly, getting more and more frequent in a linear fashion. This is when I started to replace components and has led to every component in the circuit being replaced.
The situation in which is blows is the same each and is basically when you have CH on or it has been on recently and you either manually turn on HW or the tank stat clicks on and turns on the HW. So in simple terms the CH is on and the HW tries to come on. The fuse blows. You replace the fuse and it all fires up and runs as per normal until the next time that same situation applies. If you reverse that and the HW is on and the CH comes on it is totally fine.
In short I have had replaced all components in the loop with brand new ones (Room stat, Tank stat, 3 way valve, Programmer, Pump & Brand new Worcester boiler). The boiler was replaced by a Gas Safe Engineer who re-checked all of the wiring and is happy it is wired correctly. After it blew fuses with the new boiler fitted we then tried another 3-way valve and a new programmer and it still blew the fuse.
I have since had an Electrician to look at the cabling in the walls as this seemed the only thing left to check and he Megger tested all the cables and found no cable or insulation faults. He suggested that the fault must be a live to neutral fault as this would blow the fuse and not trip the RCD, whereas a live to earth would trip the RCD. He also did a test on the RCD and this is working fine.
I'm at my wits end now as everything is new and the wiring has been checked both for being wired correctly and also not damaged in the walls.
This fault has been getting worse and worse for about 2.5 years and no matter what you do it seems to always blow the fuse in the same given situation. The cabling was Megger tested from the fused spur outwards to all components and gave no inclination of any fault.
Bear in mind that the system runs fine when CH or HW runs on it's own. Also when the fuse blows when you put a new one it it runs perfect again. One thing I have noted is that sometimes when the fuse blows it fuses the contacts in the tank stat.
The only thing I can think of now is to wire out every component in the circuit and run cables up the stairs to the various components just to completely disprove the wiring.
Does anyone have any ideas what to try next as I'm stuck?????
My system is a fairly simple Y-plan system with HW tank in the airing cupboard.
To try and keep this simple the problem I have is the fuse blows in the fused spur supply to the heating system - which is mounted to the wall at the side of the programmer. The RCD does not trip but the 3A fuse does blow. This problem started a long time ago and came on slowly, getting more and more frequent in a linear fashion. This is when I started to replace components and has led to every component in the circuit being replaced.
The situation in which is blows is the same each and is basically when you have CH on or it has been on recently and you either manually turn on HW or the tank stat clicks on and turns on the HW. So in simple terms the CH is on and the HW tries to come on. The fuse blows. You replace the fuse and it all fires up and runs as per normal until the next time that same situation applies. If you reverse that and the HW is on and the CH comes on it is totally fine.
In short I have had replaced all components in the loop with brand new ones (Room stat, Tank stat, 3 way valve, Programmer, Pump & Brand new Worcester boiler). The boiler was replaced by a Gas Safe Engineer who re-checked all of the wiring and is happy it is wired correctly. After it blew fuses with the new boiler fitted we then tried another 3-way valve and a new programmer and it still blew the fuse.
I have since had an Electrician to look at the cabling in the walls as this seemed the only thing left to check and he Megger tested all the cables and found no cable or insulation faults. He suggested that the fault must be a live to neutral fault as this would blow the fuse and not trip the RCD, whereas a live to earth would trip the RCD. He also did a test on the RCD and this is working fine.
I'm at my wits end now as everything is new and the wiring has been checked both for being wired correctly and also not damaged in the walls.
This fault has been getting worse and worse for about 2.5 years and no matter what you do it seems to always blow the fuse in the same given situation. The cabling was Megger tested from the fused spur outwards to all components and gave no inclination of any fault.
Bear in mind that the system runs fine when CH or HW runs on it's own. Also when the fuse blows when you put a new one it it runs perfect again. One thing I have noted is that sometimes when the fuse blows it fuses the contacts in the tank stat.
The only thing I can think of now is to wire out every component in the circuit and run cables up the stairs to the various components just to completely disprove the wiring.
Does anyone have any ideas what to try next as I'm stuck?????