possible 3 port valve fault??

[seco services]

Grey shouldn't be in same terminal as the orange.
Only the cylinder stat call should be.

 

[vicvapour]

Grey shouldn't be in same terminal as the orange.
Only the cylinder stat call should be.

Sorry, i should have made myself clearer, terminal 8 is linked to the orange wire from the 3 port and hot water on from the cylinder theromstat.

The grey wire (hot water off) connects in the 3 port and opens the port to its A position

 

[seco services]

The grey wire (hot water off) connects in the 3 port and opens the port to its A position

And hold it in last position when ch/hw off.
Giving 100v on orange.

 

[vicvapour]

The grey wire (hot water off) connects in the 3 port and opens the port to its A position

And hold it in last position when ch/hw off.
Giving 100v on orange.

Just been thinking , its possible that the port is stuck permanently open will this create a permanent demand for heat, what do you think?

ie valve gone instead of programmer?

 

[seco services]

I don't think programmer.

I would like to know what he means by he moves the valve and it stops.

Just been thinking , its possible that the port is stuck permanently open will this create a permanent demand for heat, what do you think?

If ch was last port of call it will stay open anyway as the 230v on the grey will hold it there. from hw off or satisifed.
So the only power on valve willbe 230v on grey, but gives 100v out the orange.

The only way to get 230v on orange demand for heat would be if theirs still 230v on white.

 

[mysteryman]

... or there is still a call from the cylinder thermostat.

 

[D_Hailsham]

So the only power on valve will be 230v on grey, but gives 100v out the orange.

The voltage is deliberately reduced so it cannot operate the gas valve when the mid-pos valve is "parked" in the CH only position. However, there have been cases where the gas valve operates even when the orange wire has only 100V on it.

The OP needs to identify the source of the voltage firing the boiler - either the valve orange wire of the HW thermostat call wire.

Here's how to do it:

Turn power OFF
Set programmer to HW OFF and CH OFF
Set room stat low and HW stat low
Disconnect the wire from cylinder thermostat to same terminal as valve Orange wire.
Turn power ON
Turn CH ON and room stat high - boiler should light
Check only CH is getting warm
Turn room stat low boiler should go out
If boiler does not go out, check voltage on Orange wire
If 230V - mid-pos valve is faulty
If 50-150V - gas valve problem

A further check is to turn room stat up (boiler lights) and then CH OFF at programmer and see if you get the same result.

If the boiler goes out when the room stat is turned down or CH is turned OFF, the problem lies in the HW thermostat.

 

[vicvapour]

Excellent idea Mr Hailsham!!

 

[colinwrightson]

UPDATE.

eng failed to turn up!!

what i have noticed is that when ch reachs temp and stat turns off, the pump stops running,but if hw is on aswell then switched off the pump still runs even tho ch and hw switched off.

if ch is off and i switch on hw for 2 hours,after 2 hours and programmer switches off then pump upstairs in airing cupboard is still running and does not turn off until i remove valve and then replace it

 

[vicvapour]

The valves sometimes can get stuck in certain postions, if you replace it (on newer valves you can just replace the head) is will cure the problem.

 

[D_Hailsham]

what i have noticed is that when ch reachs temp and stat turns off, the pump stops running,but if hw is on as well then switched off the pump still runs even tho ch and hw switched off.

if ch is off and i switch on hw for 2 hours,after 2 hours and programmer switches off then pump upstairs in airing cupboard is still running and does not turn off until i remove valve and then replace it

Why haven't you done the sequence of tests I posted earlier?