Heating wont turn off

[MartyMalabu]

That's useful, but would it be possible to post a pic of the junction box/chock block from slightly further away, so we can see the cables and identify which wires go together? We then might be able to identify the reds in 8!

They go through a hole in the floor with all the other wires, so it may be difficult to tell. I will try and take another picture anyway.

EDIT: Two pictures, sorry about the really poor quality; the lighting is not good in that room at night. If better quality ones will help I can do them again tomorrow in daylight :
//www.diynot.com/network/MartyMalabu/albums/8578/34336
//www.diynot.com/network/MartyMalabu/albums/8578/34337

Have you put a meter between the neutral and 8 to see if/when it goes live? Do it for each red in turn.

One of them stays at 0v, the other goes to 240 with CH on on the programmer - but drops to 170v with nothing on on the programmer. I tried to do a con-check from the other red to the White terminal (expecting it to be the stat, but it showed open circuit).

Why is there a Honeywell wiring centre hiding behind the terminal strip?

All the wires come into this box but are joined using the chockblock. This is how the fitter hired by Persimmons builders did it in 2002. I assume from your question this is not the standard way of doing it?

 

[MartyMalabu]

matt1e, thanks for these, results are below. Two things to mention

1. The system is was wired normally except that all 5 valve wires were removed.
2. All measurements were done to both neutral and to earth and they were the same in every case.

Sometimes it's easier to trace these types of faults with the valve out off the equation as the internal circuitry in the actuator can lead to confusing results, so to check the wiring disconect the valve wiring then

turn both stats down and turn HW and CH off at the programmer
now check for 240v at the terminal that the grey would connect to
reference this terminal to neutral and earth to make sure that polarity is ok it should be 240 ish in both cases (this is important)
now check that the terminals that are normally connected to valve white and orange are at 0v

Grey 240v
White 0v
Orange 39v

now turn HW on at the programmer
same tests should be same results

Same as above including the 39v

now turn the cyl stat up
the terminal that valve grey connects to should now be 0v and terminal orange should be now 240v (the boiler should now be firing too)

Grey46v
White 0v
Orange 240v
Yes - boiler fired up

leave HW on and cyl stat up and turn on ch
check that terminal white is still at 0v

Grey 50v
White 80v
Orange 240v

then turn room stat up
terminal white should now be 240v

Grey 55v
White 240v
Orange 240v

now check that turning off CH at programmer removes voltage from terminal white

Grey 44v
White 0v
Orange 240v

next leave both HW and CH on and both stats turned up...

Grey 50v
White 240v
Orange 240v

... then turn the cylinder stat down
in this position the boiler should stop firing and both terminals that feed valve white and valve grey should be at 240
valve orange should be 0v,

Grey 240v
White 240v
Orange 39v

now using a jumper bridge terminals valve orange and valve white
the boiler should now fire again

Yes the boiler fired up when I linked these two.

This will confirm that the wiring and controls are ok

There are a lot of midway voltages there so possibly not ?

Thoughts please, thanks a lot.

 

[MartyMalabu]

I havent read through the whole thread but thought this might be worth a mention as I vaguely remember a similair fault being "fixed" with this.

//www.diynot.com/forums/viewtopic.php?p=823510#823510[/QUOTE]

Thank you for the post, but that link does not seem to work.

 

[matt1e]

There are a lot of midway voltages there so possibly not ?

Thoughts please, thanks a lot.

if you have disconected the valve then these voltages are down to either a wiring fault (nail through a cable ), faulty programmer
or damp (very plausable considering the readings you are getting)
take the yellow out of terminal 4 and repeat your tests

matt

 

[picasso]

try again

//www.diynot.com/forums/viewtopic.php?p=823510#823510

 

[MartyMalabu]

if you have disconected the valve then these voltages are down to either a wiring fault (nail through a cable ), faulty programmer
or damp (very plausable considering the readings you are getting)

Very interesting options. I can see no evidence of leaks near the boiler of programmer or anywhere else (the house is not damp) , also pretty sure that noone has been hanging pictures or doing any DIY in a while which would cause a wiring fault in that way. Which would bring the programmer into the frame.

take the yellow out of terminal 4 and repeat your tests

Just want to make sure which wire to remove. I assume you mean terminal 4 on my chock block, rather than terminal 4 on the conventional layout?

If so, I am to remove the switched live to the boiler which goes from the connection with cyl stat T1/Orange?

Also, I assume I need to measure again with the valve removed?

thanks again.

 

[matt1e]

yes terminal 4 of your choc block

(note to picasso your link still doesn't work)

 

[picasso]

yes terminal 4 of your choc block

(note to picasso your link still doesn't work)

this is the jist of the thread

Thanks for that Andy. I rang Worcester Tech today & they confirmed what you said about the capacitor, it seems they've known about this for a while yet obviously decided this bit of information is not worthwhile putting in the MIs for the boiler.
For future reference the capacitor is a 0.47uF 275v MPX2, £1.58 from Maplins
This links the neutral & switched live to boiler ( Orange wire in the wiring center )

the op had the same problem with the boiler firing up with stray voltages from a honeywell 3 port valve and what the fix was, no idea if its the same problem but it could be.

 

[matt1e]

yes terminal 4 of your choc block

(note to picasso your link still doesn't work)

this is the jist of the thread

Thanks for that Andy. I rang Worcester Tech today & they confirmed what you said about the capacitor, it seems they've known about this for a while yet obviously decided this bit of information is not worthwhile putting in the MIs for the boiler.
For future reference the capacitor is a 0.47uF 275v MPX2, £1.58 from Maplins
This links the neutral & switched live to boiler ( Orange wire in the wiring center )

the op had the same problem with the boiler firing up with stray voltages from a honeywell 3 port valve and what the fix was, no idea if its the same problem but it could be.

there's a few boilers like that, Viessmenn spring to mind for one
so could be

 

[MartyMalabu]

These readings are with the yellow (switched boiler live from orange wire ) removed from the connector, and with all 5 valve wires removed from the connector again too :

matt1e, thanks for these, results are below. Two things to mention

1. The system is was wired normally except that all 5 valve wires were removed.
2. All measurements were done to both neutral and to earth and they were the same in every case.

Sometimes it's easier to trace these types of faults with the valve out off the equation as the internal circuitry in the actuator can lead to confusing results, so to check the wiring disconect the valve wiring then

turn both stats down and turn HW and CH off at the programmer
now check for 240v at the terminal that the grey would connect to
reference this terminal to neutral and earth to make sure that polarity is ok it should be 240 ish in both cases (this is important)
now check that the terminals that are normally connected to valve white and orange are at 0v

Grey 240v
White 0v
Orange 39v

Grey 240v
White 0v
Orange 59v

now turn HW on at the programmer
same tests should be same results

Same as above including the 39v

Same as above including the 59v

now turn the cyl stat up
the terminal that valve grey connects to should now be 0v and terminal orange should be now 240v (the boiler should now be firing too)

Grey46v
White 0v
Orange 240v
Yes - boiler fired up

Grey40v
White 0v
Orange 240v
No - obviously no boiler fire up, as not connected this time

leave HW on and cyl stat up and turn on ch
check that terminal white is still at 0v

Grey 50v
White 80v
Orange 240v

Grey 40v
White 80v
Orange 240v

then turn room stat up
terminal white should now be 240v

Grey 55v
White 240v
Orange 240v

Grey 47v
White 240v
Orange 240v

now check that turning off CH at programmer removes voltage from terminal white

Grey 44v
White 0v
Orange 240v

Grey 40v
White 0v
Orange 240v

next leave both HW and CH on and both stats turned up...

Grey 50v
White 240v
Orange 240v

Grey 48v
White 240v
Orange 240v

... then turn the cylinder stat down
in this position the boiler should stop firing and both terminals that feed valve white and valve grey should be at 240
valve orange should be 0v,

Grey 240v
White 240v
Orange 39v

Grey 240v
White 240v
Orange 60v

now using a jumper bridge terminals valve orange and valve white
the boiler should now fire again

Yes the boiler fired up when I linked these two.

No, obviously the boiler did not fire up as it is not connected.

In summary then, removing the Yellow switched live to the boiler, does not seem to have affected the test results. All that is connected here is the programmer & both stats (and some neutrals and earths obviously).

your thoughts please. Thank you.

 

[matt1e]

go to the first test, HW off CH off on programmer
unclip the programmeer from its socket and see if the voltage on the orange disappears

a photo of the programmer socket would be useful

 

[MartyMalabu]

go to the first test, HW off CH off on programmer
unclip the programmeer from its socket and see if the voltage on the orange disappears

Yes all three voltages measured drop to 0v

a photo of the programmer socket would be useful

//www.diynot.com/network/MartyMalabu/albums/8578/34346
Thanks.

 

[matt1e]

ok now link L and 1 at the programmer and measure at the orange again

 

[MartyMalabu]

ok now link L and 1 at the programmer and measure at the orange again

To confirm, this is linking HWOFF to Live ?

Pinout on programmer label says

N
L
1 HWOFF
2 (CH OFF)
3 HWON
4 CH ON

Edit:
Cylinder stat turned down,
L->1 gives

Orange 60v
Grey 240v
White 0v


Edit:2
---------------
If I measure on T1 on the cyl stat I get 60v.
If I remove the black wire from T1 and measure T1 I get 0v

The problem is that the black wire is now not connected to anything at either end, but still measures 60v at each end

The cable is about 2 feet in length (from the cyl stat to the connector block) it does not appear damaged. Is it worth changing it?

Edit 3:
-------------
Can't get hold of any four core cable today, so have replaced just the black wire for now between T1 and the orange connector, to allow me to retest. However... for the life of me I cannot get the programmer back onto the backplate. I even removed the backplate from the wall so I could squeeze the two together. I managed to get them to click but they did not look properly connected and when I turned power back onto the boiler, the programmer would not turn on.

Help please. How do I get an ST6400C programmer back on its backplate when it does not want to go ?

 

[matt1e]

Hi sorry been out to lunch

engage the top off the proggrammer into the top off the back plate at about a 45 degree angle then hinge it down