constant overflow

[malbro]

my mothers overflow seems to be constantly flowing/dripping
this seems to start when the shower has been in use and never seems to stop for days on end.
I have been up in the loft a few times and my diagnosis is. when the shower is running the level in the tank (pic 1) drops until the ballcock opens at which point it starts to fill up again. Seems logical.
Now when the shower is turned off and the pump cuts out (around 10 seconds later) i can phisicly see the water coming back into the tank from the bottom outlet of the tank (see pic 1 again- it disturbs the muck on the bottom of the tank as it flows back in) this continues until it reaches the overflow outlet and then continues for what seems like hours/days at a time.
the pump (pic 2) does not seem to have any control valve on so turning it down seems impossible???
its a fairly old system (pic 3) and it looks like the (shower tank) is connected to the hot water header/boiler tank??
what can be done to stop this problem as its now causing the walls outside to become damp and is starting to affect the walls inside (peeling paint etc)
any advice on solution would be greatly appriciated

ps edit on the photo front cant seem to get them on hopefully i wont need to????
malbro

 

[Plumbstar Tom]

The shower may well be back feeding so you will need to check the non return elbows



Just save your pictures to your documents and click the paper clip button when on 'add reply' to show them to us, makes life easier

 

[malbro]

The shower may well be back feeding so you will need to check the non return elbows



Just save your pictures to your documents and click the paper clip button when on 'add reply' to show them to us, makes life easier

def back feeding through the pump?? as the pump is connected to the tank and i can phisicly see the water flowing back into the tank from the outlet at the bottom of the tank
Where are the non return elbows???

ps still having bother with pics
thanks

 

[Plumbstar Tom]

the shower should have non return valves in it as well as the pump

They are also called check valves and permit water to travel through them one way only so it cannot go back on itself

is this a single pump or a twin?

 

[malbro]

the shower should have non return valves in it as well as the pump

They are also called check valves and permit water to travel through them one way only so it cannot go back on itself

is this a single pump or a twin?

problem is i cant get access to the shower as the pipework is tiled in.
but i cant see any NRV's anywhere on the pipework leading to/from the pump
still trying to sort pics

 

[Plumbstar Tom]

they may be in the elbows to the shower, pics would be great, can you get to the pump?

 

[malbro]

its accepting every picture from my files but the tank/pump ones
i could post some lovely ones from Turkey and some nice shots of me on the beach but im guessing they wont solve the problem 😡
yes the pump is right next to the water tank directly above the shower (in the loft)
one thought though if the nrv's are on the pipework to the shower? that will only stop the water coming back up to the pump?
the problem seems to be the pump is pumping a hell of a lot more water backwards into the tank than could possibly be stored in the pipework to the shower
it seems as if its coming from the hot water tank then back through the pump into the tank as it cant get down through the shower when its not running ??

ppp
pppp

would you like to pm me with an e mail add and i could sent the pics as its not accepting them onto here ??