Help wanted with FAULTY traditional CH system, (Honeywell Y Plan)

[vintageaxeman]

Good morning!


I have a problem with my central heating system…..and am wondering if anyone can help.


The system:


1. 15 year old detached house, with a 15 yr old Honeywell Y Plan CH system, which to all extents and purposes works FINE.


2. Boiler is a traditional ‘IDEAL Classic’ boiler, fitted inside the garage, wall mounted. Balanced flue.


3, Standard steel radiators, microbore plumbing. They all get hot very quickly when the system works properly.


4. Honeywell Y System, with a 3 way valve V4073A (28mm pipe) and pump, and hot water cylinder with a Honeywell cylinder thermostat, and the junction box for all the wiring, is all in the airing cupboard upstairs.


5. Downstairs in the hall there is a standard Honeywell Room thermostat. Model 6360B


6. Standard programmer, was a Honeywell ST6400, is now a Honeywell ST9400C, which times the hot water and heating separately.






Everything has worked fine until this summer. Normally I can set the programmer to Hot Water, or Heating, or Both….and it can be all automatic or I can just press the Extra Hour button on either.


What SHOULD happen of course is that when the electronics calls for heat, either for the hot water cylinder, or for the central heating, it will switch the 3-way diverter valve to the appropriate pipe and simultaneously switch the boiler and the pump on.


When I ask the system to heat up the hot water, everything works. Also, when I set the system to deliver hot water AND central heating at the same time, everything works fine….radiators get hot, hot water gets to temperature, etc.


BUT….My problem is this: When I ask the system to heat up the radiators ON THEIR OWN, the pump does not switch on, regardless of the setting on the room stat in the hall.



So far, I have tried the following:


1. Turned the electricity off and checked the tightness of all the wires in ALL the components and in the wiring centre. All tight and sound.


2. Replaced the valve actuator with a new replacement. In the process I checked whether the valve in the 3 way 28mm valve body was seized and it seems fine…. it swings from side to side perfectly as far as I can see, diverting the water to wherever it needs to go.


3. I then thought I had better check out the room thermostat in the hall, so I replaced it with a new one. NO CHANGE.


4. I then decided it MUST be the programer, so I bought a new direct replacement, but the current model. Fitted it to the existing baseplate, and it works like a charm on most settings, but STILL no heating without the hot water being on.


5. It CAN’T be the cylinder thermostat.


6. There is only one live cable going to the pump from the wiring centre, and I know the pump works, so it can’t be that.


7. I can’t imagine that the boiler has anything to do with it….It’s just switched on and off when there is a demand for heat….Surely it’s nothing there….?


8. So that just takes me back to the 3-way diverter valve…..could it possibly be that the swing of the actuator is not going far enough to hit limit switches and turn the pump on? So this morning I took the actuator head off and let it dangle free, set the system to ask for heating, HOPING that I would hear the sound of the pump…..but nothing.




Other than partially draining the system and replacing the whole diverter valve, (£75), I just dont know what to try next.




Any ideas? And thank you in advance for them!

 

[joni os]

Disconnect orange wire from 3 port valve at wiring centre. With programme calling for heat only, confirm orange wire becomes live. If yes, then connecting to correct terminal at wiring centre will activate pump and boiler. If no, then check you have live going to white wire of 3 port valve. if yes problem is 3 port valve not activating internal contact. If no, check for live signal from room stat. etc.

 

[vintageaxeman]

Disconnect orange wire from 3 port valve at wiring centre. With programme calling for heat only, confirm orange wire becomes live. If yes, then connecting to correct terminal at wiring centre will activate pump and boiler. If no, then check you have live going to white wire of 3 port valve. if yes problem is 3 port valve not activating internal contact. If no, check for live signal from room stat. etc.

I will check that tomorrow or the weekend when there is some light! Thank you for your advice which sounds really useful. I will let you know what happens.
Cheers, David

 

[vintageaxeman]

Orange wire shows around 60v, white wire shows 240v.
That's on a NEW head and valve, sitting on the carpet. I presume that when you say 'confirm the orange wire becomes Live, that you mean 240v? But this CAN't be a faulty valve or head. This is the 3rd head I've tried....
Help much appreciated on this one.
By the way, I am loath to rewire (partly because the tails are all so short), but the honeywell wiring box is not done according to the printed or online Y-system wiring diagram...things are in a different order so it's really hard for a skilled amateur like me to follow....

Where do I go next with this please?

Remember that the valve appears to respond properly, the main issue is that the pump does not come on when heating is called for.

 

[joni os]

When calling for heat only, the boiler and pump will only get 240volts via orange wire. Urge utmost caution testing 240 volts on carpet. Proper connection on earth and neutral, 3Amp fuse on phase plus RCD protection.
With 240v on white, give valve time to properly open and engage internal micro switch. You should then see 240v on orange.

 

[quality]

It is possible that you may have connected one of the 3 heads you have changed wrong

 

[BLOD]

Sounds like you're not getting 240v on your hot water off (grey) wire.
Check this first before replacing any more parts.

 

[vintageaxeman]

It is possible that you may have connected one of the 3 heads you have changed wrong

By 'one of the 3 heads', do you mean one of the wires to the 3 way valve? Ie white grey and orange?

thank you, all of you guys for your replies....

 

[Last Plumber]

Have I not read this on the electricians forum ?

If I didn't then you need to take the programmer off and look see if there is a wire connected to the DHW off terminal on the back plate.

If that is not there, that will be your problem

 

[vintageaxeman]

Have I not read this on the electricians forum ?

If I didn't then you need to take the programmer off and look see if there is a wire connected to the DHW off terminal on the back plate.

If that is not there, that will be your problem

Hi
thanks for your reply.
yes it is the same plea for help as on the electricians forum.
i wasn't sure if this was best classed as a plumbing issue....or an electrical one!
i have checked all the wires on the backplate and they're all soundly connected.
Also all the wires in the rats nest of a wiring centre are soundly if untidily connected.
my main problem is that everything has been done with 2 or 3 core plus earth cable, and where it comes through the wall behind the wiring centre, it is all mixed up and unlabelled so it is very difficult to work out which is from the downstairs stat, which is from the programmer and which is from the boiler in the garage.

 

[Last Plumber]

When I said connected I might be better asking if it's there ?

A lot of sparks ( no offence to any ), wire the Y plan without putting that wire in. I was not asking you if the connections are tight, I was asking if the Hot water off terminal has a wire on it.

As far as which forum, This one has more brain power and more skill knowledge and experience than the other side, Where Heating systems are concerned. The people on here are very bright and helpful individuals.

 

[vintageaxeman]

When I said connected I might be better asking if it's there ?

A lot of sparks ( no offence to any ), wire the Y plan without putting that wire in. I was not asking you if the connections are tight, I was asking if the Hot water off terminal has a wire on it.

As far as which forum, This one has more brain power and more skill knowledge and experience than the other side, Where Heating systems are concerned. The people on here are very bright and helpful individuals.

i realise that folk on here are bright, however on the electricians' forum they tend to flash randomly!
ok, on a Honeywell 9400c, which number terminal are you referring to? (Theyre numberred but not labelled)

 

[Last Plumber]

i realise that folk on here are bright, however on the electricians' forum they tend to flash randomly!
ok, on a Honeywell 9400c, which number terminal are you referring to? (Theyre numberred but not labelled)

Number 1 is DHW off, you need that in, have a look to see if it's there
3 is DHW on
4 is CH On

 

[Last Plumber]

Any news ?

 

[vintageaxeman]

Well people, I've solved it.
I decided that if all the connections were present and conect, and that all the valves and so on were ok, then it must be the wiring itself. What I found was that one wire from the programmer to the wiring centre that was fractured and had intermittent contact. It's the one that turned the pump and valve on when heating was called for.
SOLVED!!!!
Thank you all so much for your help!

 

[Last Plumber]

Well people, I've solved it.
I decided that if all the connections were present and conect, and that all the valves and so on were ok, then it must be the wiring itself. What I found was that one wire from the programmer to the wiring centre that was fractured and had intermittent contact. It's the one that turned the pump and valve on when heating was called for.
SOLVED!!!!
Thank you all so much for your help!

Good
Thank you for letting us know the outcome!
I for one appreciate that.
Have a good xmas ( if you celebrate it)

 

[Stoney Ground]

Well people, I've solved it.
I decided that if all the connections were present and conect, and that all the valves and so on were ok, then it must be the wiring itself. What I found was that one wire from the programmer to the wiring centre that was fractured and had intermittent contact. It's the one that turned the pump and valve on when heating was called for.
SOLVED!!!!
Thank you all so much for your help!

So yet again a bit of cable puts a stop to our lovely working systems. Bloody electricians, sooner everything's Wifi and we can put a battery in for power the better.