Central Heating pump never stops?

[JohnnyMiller100]

So, moved into a new build about 2.5yrs ago and the setup is:

1. range/kingspan XE cylinder in the cupboard with 2 thermostats (boiler and immersion), zone heating system valves and a HW valve
2. Ideal logic heat h12 in the kitchen.

Should just say everything's functioning ok, but since we moved in'd been thinking I wasnt saving much on energy compared to my old uninsulated semi, I assumed everything was ok and now have discovered this.....

Happened to be cleaning out the cupboard where the cylinder is in the hot weather, and noticed the Wilo pump attached to the cylinder plumbing was whirring away with its green light on. given that the hot water timer had been off for 4 hours and the central heating off for 2 days, I thought this was a bit weird, so went to the programmer to look. all looked fine everything off, no demand, all rads cold. opened the boiler cupboard and the flame was lit, then went out, it seems to come on every few minutes for a few mins and then go out, but its so quiet you'd never know, so I assume its being doing this short cycling since it was installed. Meanwhile the pump literally never stops unless I turn off the spur to the boiler.

Intrigued by this I looked up the wiring to the cylinder and the boiler, and then compared what I've got. The cylinder doesnt follow the installer guide which could be complicating things. But my boiler threw up something I wasnt expecting. I've got the 3 wires for the mains as expected, was expecting one other cable, a switched live for the pump, but I've also got one in the terminal next to it called aux live which appears to be a permanent live, removing it stops the pump and the boiler just sits with 00 on the display, tried connecting it to the switched live instead (along with whatever the other switched cable is, but it just displays 00.

Before I go much further and get the multimeter out..

1. is a pump ever supposed to be wired to a permanent live? seems like a monumental waste of energy and money to me for no benefit.
2. What is likely to be the additional wire in boilers switched live?

Thanks in advance!

 

[CBW]

It could be a zone valve, but because it’s on a G3 unvented system, you might not be able to do the work.

 

[MeldrewsMate]

1. Pump usually fed from the 'pump' terminal in a Logic, so that it gets about 2 mins of pump over-run after the flame goes out.
2. Pump should never be fed from a permanent live.
3. It looks like the installer somehow managed to connect a permanent live supply to the boiler's 'pump' output, thereby defeating its objective.

Just a standard heating and hot water system? No underfloor heating?

Covered by NHBC warranty?

 

[ianmcd]

one of your zone valves has a sticking micro switch