No HW or CH, potential programmer or 3 port value problems :)

[VickyS]

Hello apologies in advance for my absolute lack of electrical/ central heating/ plumbing knowledge, but really hoping someone on here can kindly assist me

I currently have no HW or CH. There is currently no signal coming out of the 3 port valve to tell the boiler to fire up. I have tried a replacement 3PV and still no signal from the orange wire so I don’t think the 3PV is the issue. Inputs from the room thermostat are 230v when on and 0v when off so I don’t think this is the problem.

When CH and HW or only HW is selected from the programmer the 3PV motors to the correct position. Between the programmer and 3PV I get
230v with both CH and HW turned off
70v with both CH and HW turned on
0v with only HW turned on

Do these changes in voltage sound correct? Or does this indicate a fault with the programmer?

Any help massively appreciated, I’m not too sure what else to try.

 

[terryplumb]

Have you changed the complete valve or just the actuator head ?
Was the system previously working ?

 

[VickyS]

I changed the whole 3PV because the old one was a fixed unit and didn’t come apart.

The whole system previously fully worked in the spring and I had HW but no CH (I left it throughout summer because I didn’t need the CH)
Beginning of September I changed the 3PV and the boiler would fire but then go out after a couple of minutes. For the last 2 months I’ve left the system off, but after the freezing weekend I’ve revisited this evening and the boiler no longer even fires.

(Please no comments about me ignoring the issue for so long )

 

[terryplumb]

When programmer is set for hot water only, it sends voltage to the hot water cylinder stat,and if that's not satisfied, voltage goes from stat directly to the terminal in the wiring centre that contains the orange wire from the 3 port valve and the switch cable to the boiler ,so fires the boiler directly. So although the orange wire to the 3port is also energised it does nothing,takes no part in firing the boiler. When measuring voltage under this scenario ,at the terminal that holds the above mentioned ( orange wire etc) what voltage are you getting between that terminal and earth ,and that terminal and neutrals ?

 

[VickyS]

with the programmer set to HW only, I’m reading 0v between both the terminal connected to the orange wire to the terminal of the neutrals and the terminal of the earth.

 

[terryplumb]

Check voltages at the hot water cylinders thermostat.

 

[VickyS]

Check voltages at the hot water cylinders thermostat.

I’m reading between earth and
1 = 240v
2 = 0v
3 = 0v
The L and N go to the immersion switch.

 

[CBW]

Those voltages in the 1st post don’t seem correct imo, have a look at this:

 

[cjcoffin]

Typical wiring diagrams here may help.

 

[terryplumb]

I’m reading between earth and
1 = 240v
2 = 0v
3 = 0v
The L and N go to the immersion switch.

Is the cylinder full of hot water ( have you used the immersion heater to do so)?
If the cylinder stat is satisfied you should get 240v at the terminal that contains the grey wire that goes to the 3 port valve

 

[VickyS]

Those voltages in the 1st post don’t seem correct imo, have a look at this:

Here are the readings I’ve just taken. I’m unable to take any for CH only as I can’t get this setting on my programmer.

 

[VickyS]

Is the cylinder full of hot water ( have you used the immersion heater to do so)?
If the cylinder stat is satisfied you should get 240v at the terminal that contains the grey wire that goes to the 3 port valve

I’ve been using the immersion, but I haven’t in the last 24hrs and the water is currently cold.
The terminal is currently reading 75v do you think this is due to a fault with the programmer?

 

[terryplumb]

What do you mean ,you can't select central heating
only on your programmer ??

 

[VickyS]

What do you mean ,you can't select central heating
only on your programmer ??

It will only allow me to slide the CH to the left if the HW is already over to the left. If the HW is off it will not allow me to turn on the heating.

 

[ianmcd]

It will only allow me to slide the CH to the left if the HW is already over to the left. If the HW is off it will not allow me to turn on the heating.

You say you have a mid position 3 port valve , so you have a fully pumped system, but your old programmer is set to Gravity, you need to remove the programmer and set it to pumped on the back then put it back on