Old Firebird 90 thermostat issue?

[Avo Mk8]

Did you conduct that experiment with both HW and CH calling for heat, or one of them, or neither?
It suggests to me that possibly at least one of those two valves is stuck, or one of the microswitches therein is welded closed.
I guess the next experiment is to find out which one is the problem. If you ensure neither HW or CH is on, and then repeat the disconnecting experiment, do you get the same result? You might hopefully find one valve disconnected turns the boiler off, but the other doesn't. It would be the one that doesn't that's the problem (or something in that circuit?)

 

[unhandymann]

Did you conduct that experiment with both HW and CH calling for heat, or one of them, or neither?
It suggests to me that possibly at least one of those two valves is stuck, or one of the microswitches therein is welded closed.
I guess the next experiment is to find out which one is the problem. If you ensure neither HW or CH is on, and then repeat the disconnecting experiment, do you get the same result? You might hopefully find one valve disconnected turns the boiler off, but the other doesn't. It would be the one that doesn't that's the problem (or something in that circuit?)

Both HW/CH on at the same time on the timer, unplugged each unit separately, then together and it will cut out.

One switch is brand new, so would assume it may be the other, they are turning the valve as they are ment to when powered on/off.

Yes I'll try switching on the controller tonight and do the same test on each valve, thank you hopefully getting closer to resolving this annoying issue.

 

[Avo Mk8]

Both HW/CH on at the same time on the timer, unplugged each unit separately, then together and it will cut out.

That seems to confirm to me that the boiler power is indeed coming via the valves, which it should.

One switch is brand new, so would assume it may be the other, they are turning the valve as they are ment to when powered on/off.

That's good the valves are doing something. The valve turning doesn't necessarily guarantee that the end travel microswitch gets operated. Or maybe the microswitch is just permanently on!

Yes I'll try switching on the controller tonight and do the same test on each valve, thank you hopefully getting closer to resolving this annoying issue.

To me the test is to turn off both CH and HW on the programmer, at which point you have said the boiler/burner still runs.
Then disconnect say the newer motorised valve.
If the boiler then cuts out, it's the new motorised valve that at fault, or it's not wired correctly!
If the boiler carries on running, it must be the older motorised valve that's faulty!

 

[unhandymann]

Hi Avomk8

Ok so test diagnosis still not sure.....


So mains switch on +

both valves disconnected
* doesn't fire (nothing works, timer has power and clicks between on/of red light comes on, with mains off the red light doesn't come on nor the switch/relay sound )

New valve disconnected & other original valve connected
* fires and runs valve operates (controller does nothing still)

New valve connected & other original valve connected
* fires and runs valve operates (controller does nothing still)

I removed the timer from the wall while both were plugged in and burner running and it shut down, so maybe a timer issue as both valves seem to be the same result?

 

[Avo Mk8]

OK clearly my suspicion of a valve being responsible is incorrect.
So that moves the problem back to the timer not doing it's job, or the wiring having an error.
I'm puzzled as to why there is a wire in terminal 2 of the timer. That is normally used when you have a 3-port mid position valve, eg "Y Plan"
Could you remind me what motorised valves you have, are they both 2 port, ie pipe in and pipe out. There's not a third pipe entering at the bottom of either?

It seems the timer itself is responsible for the 'always on' effect, but you say the indicator lights go on and off, and the relays click? Very odd.
Could you just confirm both the red indicator lights can be made to go on and off by adjusting the timer, and there is a 'click' associated with both?

 

[Avo Mk8]

Danfoss 087N6579

Question - the manual lever on those valves is not latched in the manual position by any chance?
As top pic below, not the bottom position?

 

[unhandymann]

Hi sorry not had the chance to check the timer until tonight below I've attached the readings, all other terminals are not live with the mains on.

The L and number 2 have the mains power.

Both valves are on auto not on manual

 

[Avo Mk8]

Hi sorry not had the chance to check the timer until tonight below I've attached the readings, all other terminals are not live with the mains on.

The L and number 2 have the mains power.

Both valves are on auto not on manual

Thanks for the update.
I don't understand why you have a voltage on terminal 2, which is the signal for "HW off", which I thought was only ever used for Y-plan systems.
Can you remind me - is the motorised valve you have a 2-port (pipe in and out) or a 3-port (3 pipe connections, one coming up opposite the motor)?

Update: having refreshed my memory of what's inside a 3-port valve, if you do have one, then I would expect there to be a voltage on terminal 2 as indicated by your meter (being fed via diode and resistor in the motorised head), assuming the valve was in the CH position.

If you do have a 3-port valve/ Y-plan system, and assuming wiring is traditional y-plan, then I think the wire currently in terminal 2 (which you measured live) should actually be in terminal 1. I'm assumoing that brown wire goes to the cylinder stat.
I believe normally the "CH OFF" terminal is not used, and the "HW OFF" terminal is used.
You might try transferring that wire, but I'm not convinced it will necessarily fix the problem!

 

[unhandymann]

Thanks for the update.
I don't understand why you have a voltage on terminal 2, which is the signal for "HW off", which I thought was only ever used for Y-plan systems.
Can you remind me - is the motorised valve you have a 2-port (pipe in and out) or a 3-port (3 pipe connections, one coming up opposite the motor)?

Update: having refreshed my memory of what's inside a 3-port valve, if you do have one, then I would expect there to be a voltage on terminal 2 as indicated by your meter (being fed via diode and resistor in the motorised head), assuming the valve was in the CH position.

If you do have a 3-port valve/ Y-plan system, and assuming wiring is traditional y-plan, then I think the wire currently in terminal 2 (which you measured live) should actually be in terminal 1. I'm assumoing that brown wire goes to the cylinder stat.
I believe normally the "CH OFF" terminal is not used, and the "HW OFF" terminal is used.
You might try transferring that wire, but I'm not convinced it will necessarily fix the problem!

It only has two electric valves, another thing I noticed also is that when the mains is on and it fires up (power to the timer but not switched to on to open the valves) the valves are powering up and opening anyway.

I just don't understand how it's just decided to do the continuous running off the mains. As it didn't happen with any one of the alterations or new items within the setup.

 

[Avo Mk8]

It only has two electric valves, another thing I noticed also is that when the mains is on and it fires up (power to the timer but not switched to on to open the valves) the valves are powering up and opening anyway.

I just don't understand how it's just decided to do the continuous running off the mains. As it didn't happen with any one of the alterations or new items within the setup.

Thank you for the clarification.
Now I understand it is an "S-plan" system, that makes things clear.

I thought it might be a motorised valve problem, but now you say that the minute you turn the setup on, both valves motor on whatever the programmer setting, so now I'm thinking the programmer is not doing the right thing!
You will see from the diagram that the valves are supposed to supply the power to the boiler, but only when they are activated. What is turning them on other than the programmer?
(Note the diagram shows a boiler that has both L and SL terminals, but I believe yours has just a L feed. So there should be no direct connection from your switched spur to the boiler as in the diagram below. The only source of power to the boiler should come from the orange wires of the motorised valves,)

The wire on terminal 2 of your programmer shouldn't be there in a typical 2 valve system, so I would suggest disconnecting it, isolating the end, and trying the setup again.

If you replaced the motorised valves, are you sure the motor supply wires (blue and brown) go to the correct places.
ie you have wired the valve brown wires to their respective thermostats, not directly to live mains?
Or to put it another way, were grey and brown wires inadvertently swapped?

 

[unhandymann]

Thank you for the clarification.
Now I understand it is an "S-plan" system, that makes things clear.

I thought it might be a motorised valve problem, but now you say that the minute you turn the setup on, both valves motor on whatever the programmer setting, so now I'm thinking the programmer is not doing the right thing!
You will see from the diagram that the valves are supposed tonsupply the power to the boiler, but only when they are activated. What is turning them on other than the programmer?

The wire on terminal 2 of the programmer shouldn't be there in a typical 2 valve system, so I would suggest disconnecting it, isolating the end, and trying the setup again.

View attachment 113907

Thank you for the clarification.
Now I understand it is an "S-plan" system, that makes things clear.

I thought it might be a motorised valve problem, but now you say that the minute you turn the setup on, both valves motor on whatever the programmer setting, so now I'm thinking the programmer is not doing the right thing!
You will see from the diagram that the valves are supposed tonsupply the power to the boiler, but only when they are activated. What is turning them on other than the programmer?

The wire on terminal 2 of the programmer shouldn't be there in a typical 2 valve system, so I would suggest disconnecting it, isolating the end, and trying the setup again.

View attachment 113907

Thank you for the clarification.
Now I understand it is an "S-plan" system, that makes things clear.

I thought it might be a motorised valve problem, but now you say that the minute you turn the setup on, both valves motor on whatever the programmer setting, so now I'm thinking the programmer is not doing the right thing!
You will see from the diagram that the valves are supposed to supply the power to the boiler, but only when they are activated. What is turning them on other than the programmer?

The wire on terminal 2 of your programmer shouldn't be there in a typical 2 valve system, so I would suggest disconnecting it, isolating the end, and trying the setup again.

If you replaced the motorised valves, are you sure the motor supply wires (blue and brown) go to the correct places.
ie you have wired the valve brown wires to their respective thermostats, not directly to live mains?

View attachment 113907

I understand the diagram and what your saying, there was no re wiring required for the new valve just plugged it in.

So both valves come on as soon as the mains is switched on, they can't be controlled via the controller at all, only way is to pull off the timer and then it cuts out (or switch of mains)

There is two lines coming into the (L) is that right? Is that for both the valves?

As testing before I unplugged each valve seperately and it was the same (powered up via mains with no control from the timer) so wouldn't that rule out the valves?

If it's not raining tomorrow I'll get out and have a decent look hopefully

 

[Avo Mk8]

I understand the diagram and what your saying, there was no re wiring required for the new valve just plugged it in.

OK, so as if you replaced valves like for like, and just plugged in the existing cables as it were?

So both valves come on as soon as the mains is switched on, they can't be controlled via the controller at all, only way is to pull off the timer and then it cuts out (or switch of mains)

So the valves must be getting power from the 'timed' side of the timer, else the boiler would carry on when you pulled it out!

There is two lines coming into the (L) is that right? Is that for both the valves?

I don't know why there are two wires. The second could be the live feed for the microswitches in the valves.
(But the 'extra' wire is single core cable, not a flex, so is part of the house wiring. Do you know if the wiring from here to the boiler is done in twin and earth, or in a conduit? Doesn't seem to be flex which is often used if the boiler is nearby)

As testing before I unplugged each valve seperately and it was the same (powered up via mains with no control from the timer) so wouldn't that rule out the valves?

Yes I agree that rather suggests it cannot be a fault in one valve, it's something else

If it's not raining tomorrow I'll get out and have a decent look hopefully

Traditionally there would be a 'wiring centre' where wires from supply, timer, valves, boiler all congregate, and that's where the fault finding is usually undertaken. It looks to me as if that Hensel junction box on the right might be your wiring centre - is that where the cable from the timer and internal cables for the motorised valves go?
Is it possible something has got disturbed in there (eg by a cable being inadvertently pulled externally and affecting something inside)?

Otherwise suspicion falls on the timer, as that seems to be supplying power when it's plugged in (whatever it's set to!) but if wired as most are, turning the HW thermostat down, and simultaneously the CH thermostat down, should stop the boiler, even if the timer is faulty!
I can't remember, did you try that?

 

[unhandymann]

Hi mate

Managed to get out today and have a look around.

The main junction box looks to be on all wires are tight and connected.

I also removed the (2) wire from the controller pin and it's still exactly the same with no response still comes on as soon as mains switch is on.

The thermostat inside the burner unit when turned down does cause the burner to turn off so that is working on that side too.

The last picture there is the inside thermostat should that also make it cut out if turned right down? Could this be at fault or is it still looking like the controller?

Cheers

 

[Avo Mk8]

Thanks for persevering!
The wiring in that box is unconventional, in that the oranges are connected together presumably to send power to the boiler, and the greys hopefully go to DHW and CH thermostats. The colours are normally the other way round, but it doesn't matter - same result so don't change it.

There's visible bare copper showing at the ends of the cables in some choc-blocks, which is poor.

Normally power goes in series from (eg) the fused spur to timer, then to thermostats, then to motorised valves, and then when the motorised valve operates it's end microswitch, power is fed to the boiler.
Any one part in that chain can stop the boiler working, but not make it stay on (that needs all the other parts of the chain to be on too).
So actually I can't see how the wall thermostat can keep the boiler running if the timer is not providing it with power, so the obvious thing is the timer is "stuck" on.
Also when you unplug the timer the boiler stops, so that supports the theory!

I'll give this some more thought and get back sometime.

 

[unhandymann]

Hi fella

So I replaced the timer with a

Honeywell thr860swe tm2

Now it's all good bar a few bugs.....

I think the wiring for the timer is the problem now.



I haven't altered it just swapped it over as it was and now the 1&2 motorised valves are powering up and turning.

But I do have a strange problem with controlling individually.


Power - ON (all good now not continuous running)


Switch ON for Heating/Rad, valve turns

Burner fires up and does the right thing


Switch ON Hot water, valve turns and comes on

The problem now is when I turn off the HW and the valve stays open

so am I right in thinking I have the OFF wiring for the HW is incorrect?

pic 1 - old timer wiring

pic 2- old timer wiring diagram

pic 3 - new timer diagram


Thanks for all the pointers I'm getting a bit better at this now but I'm used to cars with colored wires so much easier than just a bunch of brown wires