Central Heating Electrician advice required.

[doresy]

After years of working my system has now proved troublesome. The system is gravity fed hot water, pumped central heating. Single room thermostat.

The pump has just been replaced (Grundfos) and also the programmer (Danfoss)

As stated in my other post the pump is live no matter how the programmer is set. Only way to stop the pump is to lower the room stat.

Although none of the wiring has been altered I feel this is where the problem lays.

The back plate is wired thus....

Mains feed to N L
Boiler L to No.3 (DHW on)
Pump L to Thermostat then on to No.4 (HTG on)
All N to mains N

Hot water works fine on timer. Central heating is set to off as we just like to use the 1 hour boost as required. However, the pump starts up as soon a room temp. drops below 'stat setting regardless of the fact that the programmer is set to off for heating. (the boiler does not fire up for this though.)

Is it ok to re-route the pump to No.3 (DHW) via the room 'stat so it too comes on with the boiler when hot water is programmed on but having control with the 'stat ? Then we could still have the 1 hour boost for heating just by pushing the HW button.

 

[Dan Robinson]

Yes.

Or you could just by a new programmer.


Not a a very efficient system though.

 

[Agile]

The pump has just been replaced (Grundfos) and also the programmer (Danfoss)

Full marks for correct spelling of those two brands!

You would be surprised how many professionals get it wrong!

I don't know if those boilers have their own pump, but it they don't and you're in doubt I would fit a spearate 15-60 Grunfos, but mount the service vavels for a 180mm long pump - then should you need a bigger push you change change it for a 25-55 instead. In the mean time you just use a 50mm extender.

Of course its sometimes all down to too much sake !

 

[doresy]

Yes.

Or you could just by a new programmer.


Not a a very efficient system though.

As stated, the programmer has been renewed but does exactly what the old one did (thought I made that clear)

 

[doresy]

The pump has just been replaced (Grundfos) and also the programmer (Danfoss)

Full marks for correct spelling of those two brands!

You would be surprised how many professionals get it wrong!

I don't know if those boilers have their own pump, but it they don't and you're in doubt I would fit a spearate 15-60 Grunfos, but mount the service vavels for a 180mm long pump - then should you need a bigger push you change change it for a 25-55 instead. In the mean time you just use a 50mm extender.

Of course its sometimes all down to too much sake !

Spelling is your thing, eh?

 

[Agile]

No, not greatly mine but obviously yours!

I make few spelling mistakes, most typing faults!

 

[dcawkwell]

Yep.
If the pump and programmer have been replaced it certainly isn't either of those. But someone with even basic electric knowledge would have been able to identify that without replacing either.

I suggest rewire should find the problem.