Central Heating Hot Water query.

[Guitarguy]

Hi, I've recently moved into a new house, I say new- it's 5 years old.
The central heating system consists of
a Ferroli Optimax HE PLUS 18S Boiler, a Drayton LP722 programmer, RM homeflow cylinder, room thermostat, hw tank thermostat.
I think its a sealed system and is direct fed and an 'S' plan system. Plumbing is not really my forte so excuse my lack of knowledge!

The central heating works fine and as it should and there is plenty of hot water- that's all good.
However, the hot water appears to be permanently ON. The programmer has settings for on, off, timed, once etc, selecting either of these settings has no effect, the boiler doesn't kick in or it doesnt appear to go off, turning the HW tank thermostat down and then up again later on will make it kick in, also turning the whole lot off via the main switched fused spur will make it go off.
Altering the programmer for the central heating works as it should and the boiler reacts accordingly. The immersion heater is not on constantly either as i've checked.

Would anyone be able to shed some light on this? I'm thinking maybe the programmer is faulty or is the system even wired correctly?

 

[Dan Robinson]

Ferroli Optimax HE PLUS 18S

Oh dear

The central heating works fine

Don't get used to that.

it's 5 years old

Must be a record.

Could just be a bit of dodgy wiring causing the problem.

 

[Guitarguy]

Pics of it, and the scruffy wiring

 

[muggles]

Hard to tell what's connected to what from those pics although it looks OK. Might be a dodgy two-port valve. Follow the black wires to their terminus, which will be a valve. The one on the pipes to the cylinder may be faulty. Are you any good with a multimeter?

 

[jackthom]

Can you post a closeup of the DHW 2 port valve, and do you have a multimeter?

 

[Guitarguy]

Heres some pics, yes i'm good with a multimeter

 

[jackthom]

With the DHW set to OFF at the programmer check the voltage between one of the Earth connectors and number 8 in the wiring centre.
That will show whether the DHW valve is being told to open and fire the boiler, next time it starts heating water when it shouldn't be.

That opening voltage is being supplied by the blue wire connected to number 14. Can you trace where that comes from? It should be the cylinder thermostat.

EDIT: Looking at the other photos 14 is from the cylinder stat and the stat gets the DHW ON voltage via number 15, which in turn comes across from number 10 .

10 should come from the programmer so measuring the voltage there might indicate whether the programmer is giving HW ON when it shouldn't be.

If 10 is permanently Live when DHW should be OFF, chances are either the programmer wiring is somehow crossed or the programmer is knackered.

Hope this rambling post isn't too confusing