Potterton Problem

[craigmc72]

Hi
I have bought a new house with an old boiler. The problem is i cant get hot water without putting the heating on even if i select hot water only on the programmer.
The boiler is a potterton profile 40e
The programmer is a horstmann c27
It has a honeywell y plan 3 pos diverter valve

How its wired
Boiler to programmer

Live to Live
Neutral to Neutral
Earth to Earth
live S/W x 2 to terminal 3

junction box (if you can call it that they have used a conn block with tape.)

programer terminal 3 to live on pump
programer terminal 4 to orange wire on valve
all neutrals connected on valve and pump via programmer neutral
and thats it. no sign of the cylinder thermostat wiring.

The system seems to be a open vented fully pumped I think . I will need to rip up the floor to check for more valves.

Hope someone can help.

cheers

 

[xr4x4]

Try manually moving the lever on the zone valve.

 

[Aquilani]

Sounds like the motorized valve.

 

[Space cat]

A three port valve like yours rests in the HW position. The programmer only has to supply power - from terminal 3 in your case - to the boiler's gas valve and the pump. I would expect to find a cylinder stat between terminal 3 and the boiler/pump but you seem to have direct connections. Do you have a cylinder stat?

In order to get heating as well, the controller drives the valve to a mid-position so that boiler water also flows to the radiators. The connection from terminal 4 to the valve will be doing this. Note that the demand for hot water is still running the boiler and pump.

Now for the puzzle, Since you can get heating and hot water at the same time, your boiler and pump must be working but why can't you get hot water on its own? Time for some testing. When you set the controller for hot water only, does the boiler light - and does the pump run?