central heating electrical problem

[johnsm]

my programmer burnt out and i am going to replace it but before i do you guys told me to check the wiring because if there is a short in the wiring it will burn out the new programmer,at the moment i have bypassed the programmer by joining the three wires together,the three wires are,a live,thermostat which is linked to the pump and the boiler i think,,the central heating works for a few hours then blows the 13 amp fuse at the supply switch,how do i go about checking the wiring and what should i check first,its a baxi back boiler gravity fed.any help will be appreciated as it freezing up here in scotland.
and oblige johnsm

 

[tomy]

seperate the feeds to the pump and the boiler , and connect just the pump up to mains and let it run without any power to the boiler and see if the fuds if it does then your pump has had it , if not the fault is on the boiler blows , but you need to workk out exactly where each wire goes , or you can take the existing wire from the pump and just connect some flex up to it and plug it in to a socket

 

[Fluffster]

13amp
Should be a 3amp fused switch supply.
If you are blowing 13amps then certainly do not attempt to connect the new programmer until you find the fault.

Pete

 

[DP]

No wonder the programmer is burnt. It will be trying to be a 3 bar fire. Fuse to central heating system should NEVER be a 13 amp link. 2amp is preferable, three is stuck for a fuse and 5 as an emergency, never a 13 amp link.

 

[johnsm]

hi guys,i found the problem,it was the boiler connecting wire that was shorting against the frame of the boiler,as its a back boiler i had to strip the fireplace and the front of the boiler to get to it,it had been doing it for a while ,the wire bas burnt and hard ,it was the neutral wire .thanks for your help.
nice and warm johnsm

 

[Fluffster]

Good to hear I hope you have inserted a 3amp fuse?

Pete

 

[kirkgas]

johnsm you didn't say if you are a gas engineer, so apologies if you are!! but if not i wonder if you have properly tested the gas fire connections you have disconnected while accessing the BBU