Advice needed - changing ST1250 to 9400c but CH doesn't work

[cjbell68]

Hi - hope someone can help.

I have a three port Honeywell 4073a valve, cylinder stat, Honeywell room stat and Honeywell ST1250 controller.

I tried replacing the ST1250 with a 9400c but can only get the HW circuit to work - no CH. (Note I got the info for the backplate change from Honeywell and have double checked what I did with them).

With the old programmer I can get HW or HW+CH so I assume the controls all work correctly. I also assume that as I have a 3 port system it should be possible to have independent control of the HW and CH circuits (e.g. it is possible to run the CH when HW is off).

I THINK the problem is the 10 block wiring centre in the airing cupboard - the wiring here doesn't match the Y plan layout supplied with the 9400c. In particular there are two wires which terminate at the block and don't connect with any others - so I assume one of these is the CH ON from the programmer and should be wired differently.

I've made a drawing of the wiring setup together with some info on the current backplate wiring for the ST1250, and a circuit diagram from a sticker inside the ST1250.

I hope the diagram will be easily understood by someone on here who could advise whether my reasoning is correct and offer some suggestions as to how the wiring should be modified to allow the 9400c to work correctly.

Sorry for the long winded post and hope someone has some advice.
Thanks in advance
Colin

Untitled

• cjbell68
• 13 Mar 2010
• 1

I think I've added the image correctly

 

[electronicsuk]

I haven't looked at it too closely, but I suspect you may have the two three core cables for the programmer and room stat confused in your diagram. It would make much more sense, electrically, if they were the other way around. Otherwise, what is bringing your pump on when CH is demanded?

EDIT: Also, where is your incoming mains supply in all of this? It doesn't seem to be shown on your diagram anywhere.

EDIT 2: OK, completely disregard the above! I have now looked more closely at your diagram, and what I said with regard to the room stat/programmer being the wrong way around doesn't make any sense at all

 

[cjbell68]

I haven't looked at it too closely, but I suspect you may have the two three core cables for the programmer and room stat confused in your diagram. It would make much more sense, electrically, if they were the other way around. Otherwise, what is bringing your pump on when CH is demanded?

EDIT: Also, where is your incoming mains supply in all of this? It doesn't seem to be shown on your diagram anywhere.

EDIT 2: OK, completely disregard the above! I have now looked more closely at your diagram, and what I said with regard to the room stat/programmer being the wrong way around doesn't make any sense at all

I was expecting there to be a mains supply in the airing cupboard but there isn't. I've described all the wires that are there. There is a LNE connection to the programmer - I'm not sure if it's correct but I was assuming that in that case the live feed should be transferred via the programmer out on the CH ON (3) and HW ON (4) terminals. I don't know if the programmer should be switching 240v though. [EDIT - on second thoughts it probably is!]

I made those assumptions on the 'stat and programmer based on some other postings on here about wiring for the 3pt valve - and also because the pump is getting it's live from terminal 8. They are assumptions for the moment - I was hoping the layout would be close enough to what it should be for someone to point out what was stopping the CH firing in the new setup. I have a multimeter but I'd like to avoid tracing the circuits if I can avoid it.

 

[MANDATE]

The 3 port mid position valve operates over 2 sections.
If HW only is required and CH not on, then the valve stays in the rest position.
If CH only is required and HW not on, the room stat provides the power the valves white wire which drives the motor. But this action stops at mid point by the triggering of a micro switch.
The valve has a grey wire, which in this case should be 'live', so this takes over from the white wire so the motor can continue over the final section. ( a second micro switch is also triggered during the second section to allow power out of the valves orange wire to fire boiler.
I believe your problem relates to the 'grey' wire not being 'live'.
There should be two sources of supply to the 'grey'. One comes from the satisfied terminal of the cylinder stat so power is diverted to the 'grey'.
But this would be of no use if HW was not on.
The second source comes direct from the programmer from the HW OFF terminal.
On your diagram I could not identify a wire that meets this requirement.

 

[electronicsuk]

I believe your problem relates to the 'grey' wire not being 'live'.
There should be two sources of supply to the 'grey'. One comes from the satisfied terminal of the cylinder stat so power is diverted to the 'grey'.
But this would be of no use if HW was not on.
The second source comes direct from the programmer from the HW OFF terminal.
On your diagram I could not identify a wire that meets this requirement.

Perhaps the wire in terminal 6 of the wiring centre should actually be in terminal 10? No guarantees of course, as the crimped joint that's given rise to the change in core colours between the two ends of the programmer wiring makes it hard to identify the individual cores, unless you have a multimeter or continuity tester.

 

[cjbell68]

The 3 port mid position valve operates over 2 sections.
If HW only is required and CH not on, then the valve stays in the rest position.
If CH only is required and HW not on, the room stat provides the power the valves white wire which drives the motor. But this action stops at mid point by the triggering of a micro switch.
The valve has a grey wire, which in this case should be 'live', so this takes over from the white wire so the motor can continue over the final section. ( a second micro switch is also triggered during the second section to allow power out of the valves orange wire to fire boiler.
I believe your problem relates to the 'grey' wire not being 'live'.
There should be two sources of supply to the 'grey'. One comes from the satisfied terminal of the cylinder stat so power is diverted to the 'grey'.
But this would be of no use if HW was not on.
The second source comes direct from the programmer from the HW OFF terminal.
On your diagram I could not identify a wire that meets this requirement.

Thanks for that - helpeful information.
Do you agree with my assumptions on which of the three unknown wires is linked to the boiler/room stat/programmer? I presume so.

To check my understanding re. the live feed is correct - I need two live feeds to get the CH only function of the valve? So the yellow wire (W12) from the room stat' is enough to get the valve part-way - then the grey wire should take over - but it's not getting the live from the HW as this is satisfied - so I am missing another live feed?

This may tie in with my view that the wire from the programmer that goes to block 6 should be connected to block 10 - feeding the grey wire with live?

Hope I've understood correctly and thanks again for your help.

(I may try this later - once the house is a bit warmer than it is now - and I have time to swap out the old programmer !)

 

[cjbell68]

I believe your problem relates to the 'grey' wire not being 'live'.
There should be two sources of supply to the 'grey'. One comes from the satisfied terminal of the cylinder stat so power is diverted to the 'grey'.
But this would be of no use if HW was not on.
The second source comes direct from the programmer from the HW OFF terminal.
On your diagram I could not identify a wire that meets this requirement.

Perhaps the wire in terminal 6 of the wiring centre should actually be in terminal 10? No guarantees of course, as the crimped joint that's given rise to the change in core colours between the two ends of the programmer wiring makes it hard to identify the individual cores, unless you have a multimeter or continuity tester.

Yes - as per my other reply just now I think I'll try that - given the understanding about the live feeds needed to the white/grey wire it suggests that the current controller works as it has two options - HW only which works - or CH but ONLY with the HW. When I turn the cylinder stat down to 0 to test the CH only circuit there is no live feed to the grey wire from the HW stat - and presumably no live feed from the programmer (because the wire is on block 6 on it's own).

As for the other wire from the boiler (W05) I presume this is isolated on block 3 as the other two wires are acting as neutral and switched live - and they just happened to use 3 core and earth cable?

 

[D_Hailsham]

There a large number of question marks all over your diagram which is worrying as you will never solve the problem if you don't what what each wire does. If you have a meter you can easily sort that out.

Turn power off to system. (This is important as you don't want to blow a fuse when testing. If you are unsure where the wiring centre gets its power from, use the meter to check there are no volts on any terminals)

Disconnect all problem wires at the wiring centre.

Temporarily join two wires e.g red and yellow)from one cable together.

Set your meter set ohms or continuity.

Go to each device (thermostat, programmer etc).

Check for continuity/0 ohms at the terminals with the same coloured wires connected.

If there is continuity you have correctly identified the wire to that device. Label it for future reference.

If the meter reads open circuit, you need to move to the next device until you do identify the correct one.

Break the join between the wires at the wiring centre (this is to prevent possible backfeed).

Repeat with another cable and so on until you have positively identified each cable.

You will then be able to produce an accurate drawing, which will make problem solving much easier.

 

[cjbell68]

Hi
Thanks for your advice - I've checked the wiring and found:
I was correct which wires were from the boiler, thermostat and programmer.
I made a mistake - the pump was connected to block 3 - Baxi Solo 2 has a pump overrun.

I have checked the voltages from the grey and white wires:
When call for CH only then WHITE = 240v, GREY = 240v (only available when the HW is on at the programmer and the cylinder stat is satisfied as I'm missing terminal 1 HW OFF from the programmer).
When call for CH+HW then WHITE = 240v, GREY = 0v
When call for HW only then WHITE = 0v, GREY = 0v
I had a look at the valve and it seems to be working in line with this. Also the boiler fired and the pump was working so there must be 240v from the ORANGE wire.

So after correcting the mistake I checked the wiring against Honeywell's latest wiring PDF and I think although a different block scheme has been used it is wired correctly taking the pump-overrun live into account.
I've attached a new wiring diagram. Note I assume the errant blue wire from the programmer is HW not required - but I can't detect a voltage on this with either circuit on.

There is still a problem though - if I set the programmer so HW is off, but CH is on independently I get 240v at the WHITE wire so there is CH demand - but there is no voltage at GREY (even if I turn the cylinder stat off as well) - and also the boiler and pump will not fire.

The boiler and pump will fire provided I switch HW on at the 9400c - and this is true regardless of whether or not there is HW demand (cylinder stat on or off).

I've attached a new diagram - hope there is a solution to this; the reason I got the 9400c was to control the circuits independently...

Thanks
Colin
[EDITED diagram to correct a couple of errors and add information on the fused live to the programmer)

Untitled

• cjbell68
• 15 Mar 2010
• 1

 

[matt1e]

hi colin I agree with D-hailsham there are a few question marks all over the place.it looks as though its a rehashed gravity system.anyway a few pointers for you

With the old programmer I can get HW or HW+CH so I assume the controls all work correctly. I also assume that as I have a 3 port system it should be possible to have independent control of the HW and CH circuits (e.g. it is possible to run the CH when HW is off).

the controls are not working correctly as you have no hw off connection as previously mentioned
you can still get CH but the HW has to be on as in a gravity set up
you assume correctly that you should be able to get it independently because of the 3-port but it has to be wired correctly for it to work

I THINK the problem is the 10 block wiring centre in the airing cupboard - the wiring here doesn't match the Y plan layout supplied with the 9400c. In particular there are two wires which terminate at the block and don't connect with any others - so I assume one of these is the CH ON from the programmer and should be wired differently.

you are right it does not match a y-plan as I said earlier I think its been converted from a gravity system.here are the things that are wrong with your drawing

Untitled

• cjbell68
• 13 Mar 2010
• 1

terminal 6
the cable connected here may go to the programmer for the hotwater off connection,you need to find the other end of it. it may be
1)the cable you have shown connected to terminal 1 on the programmer (is there another cable connected to L or does the x1 refer to the link?)
2) one of the two cables connected to N one the programmer
3)still buried in the utility room wall
4) none of the above
if you can locate the other end of the terminal 6 connection and successfully connect it to HW off then you will also need to connect it to the valve grey (i have shown this on the amended diagram posted below as a connection to the valve,this is for clarity,in reality you would take the connection out of 6 and connect it to 10 or rearrange everything into standard wiring centre numbering)

the cylinder stat
you have either labled this incorrectly or its wired incorrectly
common should be connected to HW on from programmer
satisfied should connect to the same terminal as valve grey
demand should connect to the same terminal as valve orange
have a look at the terminal numbers/labling and report back so someone can advise

the pump
this is connected incorrectly it should be connected to terminal 4 not 8 but see below

terminal 3
this may go to the boiler and may be for a pump connection (for pump over run.I know some solos dont have a pump over run but some may have.if so then the pump will connect here not to terminal 4
report back with the GC number on the boiler and again some one will advise
.
here is an ammended drawing and some notes but be advised this is my thoughts on your system and I would be using a meter to check the system out

View media item 20621good luck
matt

 

[electronicsuk]

There is still a problem though - if I set the programmer so HW is off, but CH is on independently I get 240v at the WHITE wire so there is CH demand - but there is no voltage at GREY (even if I turn the cylinder stat off as well) - and also the boiler and pump will not fire.

The boiler and pump will fire provided I switch HW on at the 9400c - and this is true regardless of whether or not there is HW demand (cylinder stat on or off).

Did you try connecting terminals 6 and 10 as suggested? Assuming terminal 6 is HW off from the programmer, this will provide the necessary voltage on the grey wire to motor the valve across. Or are you saying that you tried this, but have been unable to get any voltage on terminal 6 regardless of programmer setting?

 

[electronicsuk]

Hmm - just had another look at your diagram, and I'm starting to wonder about the wiring at the programmer. You appear to have three outgoing wires as follows:

1 - Permanent live (fed from L to com link)
2 - N/C
3 - CH on
4 - HW on

So, one would assume that the wire in terminal 3 ends up being red in the wiring centre, 4 as yellow, and then 1 as blue. However, if your diagram of the wiring at the programmer is correct, you would expect terminal 6 to be live all the time.

Can you remove the programmer wiring and do a continuity check end-to-end to confirm?

 

[matt1e]

hi colin
Glad to hear you have a multimeter things should get easier now!
firstly be advised that your statement about the valve is incorrect! the valve orange will be live whenever the boiler is firing because it is a common connection with the boiler live not because the valve is making it live the valve only makes this live when it is fully open and there needs to be a connection on the valve grey for that to happen

for your system to work correctly you have to have a hw off signal to the grey from the programmer and the satisfied terminal on the cylinder stat

have a good look at the instructions of the programmer
1)do you need that link?
2)where does the connection on terminal 1 go to?
3)why are there 2 connections on the neutral check that one of these are not connected to terminal 6 in the wiring centre


as mentioned check the cylinder stat!
common should be connected to the hw on terminal in the programmer
satisfied sould be connected to the same terminal as the valve grey
demand should be connected to the same terminal as the valve orange
Matt

 

[cjbell68]

Thanks matt1e - have a look at my updated diagram; I've done some more checking and revised my labelling. I think the only thing I'm missing is a live from the programmer (HW OFF?) to connect to the grey wire to make sure it has voltage even when the heating circuit is off - to connect with the grey wire as you mentioned.

I need to do some more checking on the backplate but for now I've set the channels up so they're firing at the same time, so at least there will be HW + CH and I don't have to revert to the previous backplate.

There were two neutral wires connected to the N block on the backplate for the old programmer so I will check these to see if one is the HW OFF wire which seems logical.

Thanks for your help!
Colin

hi colin I agree with D-hailsham there are a few question marks all over the place.it looks as though its a rehashed gravity system.anyway a few pointers for you

With the old programmer I can get HW or HW+CH so I assume the controls all work correctly. I also assume that as I have a 3 port system it should be possible to have independent control of the HW and CH circuits (e.g. it is possible to run the CH when HW is off).

the controls are not working correctly as you have no hw off connection as previously mentioned
you can still get CH but the HW has to be on as in a gravity set up
you assume correctly that you should be able to get it independently because of the 3-port but it has to be wired correctly for it to work

I THINK the problem is the 10 block wiring centre in the airing cupboard - the wiring here doesn't match the Y plan layout supplied with the 9400c. In particular there are two wires which terminate at the block and don't connect with any others - so I assume one of these is the CH ON from the programmer and should be wired differently.

you are right it does not match a y-plan as I said earlier I think its been converted from a gravity system.here are the things that are wrong with your drawing

Untitled

• cjbell68
• 13 Mar 2010
• 1

terminal 6
the cable connected here may go to the programmer for the hotwater off connection,you need to find the other end of it. it may be
1)the cable you have shown connected to terminal 1 on the programmer (is there another cable connected to L or does the x1 refer to the link?)
2) one of the two cables connected to N one the programmer
3)still buried in the utility room wall
4) none of the above
if you can locate the other end of the terminal 6 connection and successfully connect it to HW off then you will also need to connect it to the valve grey (i have shown this on the amended diagram posted below as a connection to the valve,this is for clarity,in reality you would take the connection out of 6 and connect it to 10 or rearrange everything into standard wiring centre numbering)

the cylinder stat
you have either labled this incorrectly or its wired incorrectly
common should be connected to HW on from programmer
satisfied should connect to the same terminal as valve grey
demand should connect to the same terminal as valve orange
have a look at the terminal numbers/labling and report back so someone can advise

the pump
this is connected incorrectly it should be connected to terminal 4 not 8 but see below

terminal 3
this may go to the boiler and may be for a pump connection (for pump over run.I know some solos dont have a pump over run but some may have.if so then the pump will connect here not to terminal 4
report back with the GC number on the boiler and again some one will advise
.
here is an ammended drawing and some notes but be advised this is my thoughts on your system and I would be using a meter to check the system out

View media item 20621good luck
matt

 

[cjbell68]

Hi, yes I tried this - after working out I had a pump overrun boiler I left the pump live connected to block three with the pump-live fed from the boiler. This leaves one other wire I tried (the blue one from the programmer) but it has no voltage. So I suspect the other end to that wire may be connected to the neutral block on the back plate - will test tomorrow.

Colin

There is still a problem though - if I set the programmer so HW is off, but CH is on independently I get 240v at the WHITE wire so there is CH demand - but there is no voltage at GREY (even if I turn the cylinder stat off as well) - and also the boiler and pump will not fire.

The boiler and pump will fire provided I switch HW on at the 9400c - and this is true regardless of whether or not there is HW demand (cylinder stat on or off).

Did you try connecting terminals 6 and 10 as suggested? Assuming terminal 6 is HW off from the programmer, this will provide the necessary voltage on the grey wire to motor the valve across. Or are you saying that you tried this, but have been unable to get any voltage on terminal 6 regardless of programmer setting?