my back boiler (part2)

[Goats left knee]

so i have taken out the electric fire and now have my back boiler blazing for about a week. just off the boiler behind the press where the pipes are... there is a red tap handle type.. if i turn it fully to the left it means that we have hot water and the cylinder upstairs is heated up (even though the immersion switch is still at OFF)

as i said it is switched off. my fire is heating this tank up?? i wont face a big electric bill???
can anyone help

 

[CockneyBlueTheFirst]

didnt see part 1 but unless you have used this back boiler before and you have had it checked out by a qualified plumber i wouldn't entertain it. You basically have a bomb in your wall if it doesn't work properly.

 

[Goats left knee]

didnt see part 1 but unless you have used this back boiler before and you have had it checked out by a qualified plumber i wouldn't entertain it. You basically have a bomb in your wall if it doesn't work properly.

thats a bit worrying.
our plumber said to light a small fire and if the pipes started rattling the pump could be siezed cos it has been lying for about 5 years+ unused.
there was no noise.
when i switch that red tap handle to the left fully we have piping hot water. otherwise it stays cold.
though this way the radiators downstairs stay cold - though with the oil heating all of them heat up

 

[CockneyBlueTheFirst]

Yes your plumber is right the pump could have seized after all that time but in your case it seems to be ok. when you turn the lever you are just sending hot water around your immersion tank to heat the cold water inside. But you have expansion valves on that system that let the air/water out if for some reason the water overheats or you lose all the water and there is just hot air in the system ( this expands more than a liquid )...these need to be checked that they still operate. Its worth getting these things done.