Potterton programmer

[minty2]

I have a potterton ep2002 programmer running an ideal classic boiler and 2 danfoss hpa2 zone valves.
Problem is that thermostats control the valves and the boiler turns on & off ok but the pump runs continuously. All lights on the programmer are as usual.
Would I be right in thinking the fault lies with the boiler pump switching circuit?
Thanks

 

[JohnD]

when was it installed?

when did it last work correctly (if ever)

whose wiring diagram are you on?

does the programmer have a pumped/gravity switch? this may be on the back (this may be irrelevant)

 

[minty2]

when was it installed?

when did it last work correctly (if ever)

whose wiring diagram are you on?

does the programmer have a pumped/gravity switch? this may be on the back.

Installed approx 5 yrs ago
Worked aprox 4 weeks ago
Not got a diagram
Switch is in pumped position
Thanks

 

[JohnD]

OK, so it has gone faulty.

you can prob get a wiring diag from the programmer makers (and this may help, to check it), but if it used to work, it is probably wired correctly.

the wiring diags I have seen from Drayton and Honeywell appear to be exactly the same, so I expect the Potterton is just a badge on a standard one.

zone valves have an output wire on the back that reports their open/closed status (after the motor has responded to call for heat/satisfied from the stat) so it might be one of them. If either valve reports "Open" status it would call for pump to run. If you have a multimeter and a wiring diag you could trace it. If it is an actuator switch, you may be able to fit a new head.



but I am just a DIYer and never had to deal with one of these so had best stop now.

 

[minty2]

OK, so it has gone faulty.

you can prob get a wiring diag from the programmer makers (and this may help, to check it), but if it used to work, it is probably wired correctly.

the wiring diags I have seen from Drayton and Honeywell appear to be exactly the same, so I expect the Potterton is just a badge on a standard one.

zone valves have an output wire on the back that reports their open/closed status (after the motor has responded to call for heat/satisfied from the stat) so it might be one of them. If either valve reports "Open" status it would call for pump to run. If you have a multimeter and a wiring diag you could trace it. If it is an actuator switch, you may be able to fit a new head.



but I am just a DIYer and never had to deal with one of these so had best stop now.

Thanks John but would this output not cause the boiler to light as well as run the pump.
Cheers

 

[JohnD]

don't know, would have to trace it through the wiring diagram. If both valves were actually closed (though one of them was signalling "open" due to a faulty end switch) there would be nowhere for the heat to go, so the boiler thermostat would not let it fire until it had cooled down.

I have a feeling that a zone valve signalling "open" is a call for heat, and the room thermostat may not go to the boiler, just to the valve. But you need to get a wiring diag to follow it through.

p.s. you can use the

button not the

button

 

[simond]

The boiler switched live needs to be checked- disconnect from the terminal in the boiler before checking with a meter. If it is always on, this is your pump problem, and it will probably be a stuck MV.

However, from your description of the problem, and assuming you haven't had anyone unqualified fiddling with the wiring (JohnD?) it will be the boiler electronics. Ideal by name, not by nature.

 

[JohnD]

anyone unqualified fiddling

never touched it