Hot Water not working if controls left on 24/7

[willidh]

Hi

I have a potterton suprima 30 boiler and a potterton EP2002 control unit.

If the hot water and heating controls are at the "on" position so that they are running 24 hours a day then the hot water does not heat up once it has been used up.

It appears that there is a fault where a component in the system is not being triggered when the hot water temperature in the cylinder drops below the threshold set by the thermostat.

If I have the controls set to "timer" or "once" then everything appears to work correctly. I.e. when not running 24 hours a day, the system gets the opportunity to reset itself somehow.

So any ideas where the fault could be?

Thanks in advance

Danny

 

[D_Hailsham]

If the hot water and heating controls are at the "on" position so that they are running 24 hours a day then the hot water does not heat up once it has been used up.

If I have the controls set to "timer" or "once" then everything appears to work correctly. I.e. when not running 24 hours a day, the system gets the opportunity to reset itself somehow.

Could be a faulty programmer.

When set to continuous, the input of most programmers is connected directly to the output. So the L terminal will link, via the programmer to 3 (HW ON) and 4 (CH on). You can check if the programmer is faulty by removing it from the back plate and making a temporary link, on the backplate, between L and terminal 3. Turn Electricity off while making the link. If the hot water then works OK, is proves that the programmer is faulty as it is not linking L to 3.