W Plan hteating question?

[JamesCollins]

The old W Plan, 3 port diverter valve. Is it true that you can't have heating on it's own UNTIL the hot water cylinder is up to temperature, even if you don't want the HW on at that time? From the diagram the power to the brown wire of the 3 port valve can't get there unless h/w cylinder is up to temperature! Horrible

 

[Whitespirit66]

Depends on your programmer, does your allow seperate hw and ch timings? W Plan is priority hw. If both hw and ch are on together on the programmer, then yes, the ch will be off until the hw stat is satisfied.

If you don't want the hw on at the time, turn the hw off on your programmer, if it allows this.

Best to change to Y Plan though. Not too difficult.

 

[JamesCollins]

Thanks for your reply.

Yep sepearate timings. Just seeing the W Plan wiring diagram, Sundial W plan, and the cylinder stat seems to HAVE to be off/satisfied to allow power to the BROWN wire of the 3 PORT. Even with hw off at the programmer!! As power goes through cylinder stat to power 3 port diverter valve.

 

[D_Hailsham]

It is called a HW Priority system!

 

[JamesCollins]

yes I know!! Maybe I can put a link between room stat call and brown wire to sort this out...... hang on let me think it's late now (long day)!!

 

[mysteryman]

If you can select DHW 'off' with CH 'on' at the prog, you take a live DHW 'off' wire from it to the CH channel, in parallel with the DHW 'sat' from the cyl 'stat.

I don't see why you want this! If you are at home and wanting CH, you surely will want the cyl hot anyway?

 

[DP]

Copied from Honeywell website

Hot Water Only Requirement - On a demand for heat from the cylinder thermostat, the pump and boiler are switched on.

Heating Only Requirement - On a demand for heat from the room
thermostat, the valve is energised, so that the hot water port is closed and
the heating port is open, and the pump and boiler switched on.

HTG and HW Requirement - When wired and installed to give HOT WATER
priority the heating will remain off until the hot water is up to the required
temperature.

 

[gaswizzard]

Some of these old W plans used a changover switch.

 

[JamesCollins]

where was the changeover switch? It's in my mums house. She has a w plan. Looking at the w plan diagram it is true you cannot get the heating (power to brown wire of 3 port diverter) if the hot water stat is not up to temp!