[APWS]

I was cleaning paint off a wall today when my hot box packed up, it starts ok and there is fire at the bottom but it will not heat all the coils when i pull the trigger, so no hot water, relied on good old wet blaster & removal gel to get job done,
any idea's guys?
cheers,

[Blast Away]

Fuel nozzle may need changing, plastic casing on shaft may be worn, flow switch might be sticking, electrodes could be miss sparking and need replacing

[BDCS]

 Does the relay stay in ? The flow switch, thermostat etc are in series which pull the relay in. If the burner starts then stops you need to see if the relay stays in afterwards to isolate the electrical from the fuel circuits. You can frig the supply to the relay to prove each side.

[Matt Gibson]

So much can go wrong with a boiler. I had a similar problem, it ended up being the fuel pump. needed to replace. But the things i had to go through to narrow it down was amazing.

[BDCS]

Bless 

[APWS]

thanks for the replies, going to take it to be looked at.