Heating Wiring Problem - cylinder thermostat not working

[Aaron b]

Deleted... Didn't see the neutral links to the valves.

 

[brianmoooore]

One of your valves need to open to call the boiler and pump. Currently it doesn't have the blues connected, this is the neutral for the internal motors.

??????????? Both valve neutrals are connected to the lower neutral terminal, D.

 

[Aaron b]

??????????? Both valve neutrals are connected to the lower neutral terminal, D.

Sorry didn't see the look links at first. You caught me before I edited.

 

[dfreitag]

Hi.

Did as I was told (earth to EFG and black to BCD) and the CylStat is finally working again!!

Thanks again for all the input!!!

(Can I ignore the last message exchange with Aaron? )

 

[Aaron b]

Hi.

Did as I was told (earth to EFG and black to BCD) and the CylStat is finally working again!!

Thanks again for all the input!!!

(Can I ignore the last message exchange with Aaron? )

Yup, ignore my input. Glad you got it working.

 

[dfreitag]

Hi all

I was wondering - do you think it's worth re-wiring the CylStat, so it's on ALL the time, as suggested by it's manual? (and what would I need to do, to achieve this?)

At the moment it only switches on when switching on the hot water..


See below revised wiring box

Many thanks!
D

 

[Aaron b]

The green/yellow is the switched live from the stat, ideally that would fed the common of the thermostat which is currently done using the blue link wire within the stat. The brown conductor to the stat could the be moved to the permanent live terminal. You would need replace the flex for a 5 core as using the earth would be naughty...

 

[dfreitag]

To be honest, the cylinder stat was just the tip of the iceberg - just trying to solve things step by step..

My real problem is that my boiler seems to be overheating constantly, even though both heating and hot water are off.

After some discussions with the (somewhat questionable?) professionals mentioned previously, my understanding is that the following is happening:

The overheating causes the boiler pump to run almost constantly, as it tries to cool itself down.
(Observing it, I don't think it's actually firing up, but I could be wrong.)

While doing so it tries to pump water into the system. But with both HW and heating valves off, there's nowhere to pump to, so the pressure rises, and it get's stuck into a loop of doing the same over and over again.
This I can only assume is torturing the pump.


Seeing that the wiring has been rather sloppy, I'm suspecting that it might be a wiring mistake or the Nest that's causing the whole issue.

What do you guys think?

Photos of the current wiring box are just above and the Nest wiring, too.

Please let me know if you need further info, images or anything else for that matter..

MANY THANKS!
D

 

[davesparks]

While doing so it tries to pump water into the system. But with both HW and heating valves off, there's nowhere to pump to, so the pressure rises, and it get's stuck into a loop of doing the same over and over again.

There should be a bypass of some sort in the pipework to prevent this from happening, usually an automatic bypass valve these days.

Your system will always continue to run the pump for a while after the demand for heating and/or hot water has gone off and the valves have closed. This is known as a pump overrun and is there to prevent excess heat building up in the boiler immediately after the burner goes off.

 

[Aaron b]

The boiler (and perhaps the pump) should be powered from the orange core from the valves. Modern boilers control the pump for overrun functions.

 

[diditrain]

I take it, your pump is inside your boiler? Ideally you need someone who knows how to test properly/safety. After demand for heating and hot water has ceased, you need to ensure that there is no voltage on Live return conductor at the boiler. Also them boilers have a link inside them that needs removing when external controls are fitted as it gives the boiler a constant demand. If the link has been left in place and your valves are shut, this may be the problem. Maybe.

 

[dfreitag]

I take it, your pump is inside your boiler? Ideally you need someone who knows how to test properly/safety. After demand for heating and hot water has ceased, you need to ensure that there is no voltage on Live return conductor at the boiler. Also them boilers have a link inside them that needs removing when external controls are fitted as it gives the boiler a constant demand. If the link has been left in place and your valves are shut, this may be the problem. Maybe.

Hi diditrain

Thanks for your input!Sounds like this could be the case..
And yes, the pump is built into the boiler.
At the moment, when on, the heating LED is blinking and the pump is constantly on (I make sure to switch off the boiler after I don't need it).

I'd love to get someone competent in to solve this all asap, but as mentioned above, I've recently had some costly and unsuccessful experience with plumbers.. and I don't quote know who to turn to for this anymore.. Even the highest rated plumber on checkatrade, who came at a price, didn't pick up something as basic as the cylstat not working..

Any advice on who to contact?? I'm in Hackney, East London..

In the meantime, I feel at this point the best thing to do is to get your valuable help and perhaps pass that information on to whoever I will be able to get in, in the hope it will help him actually solve this saga of an issue..

On that note, would you mind sharing where is that boiler link you mentioned, and what's it called officially?


Many thanks!

 

[Aaron b]

It would likely be in RT terminal and jumping from the line conductor where the power connects to the boiler (X1 on the PCB). The manual for your boiler isn't particularly clear.

 

[diditrain]

Hi diditrain

Thanks for your input!Sounds like this could be the case..
And yes, the pump is built into the boiler.
At the moment, when on, the heating LED is blinking and the pump is constantly on (I make sure to switch off the boiler after I don't need it).

I'd love to get someone competent in to solve this all asap, but as mentioned above, I've recently had some costly and unsuccessful experience with plumbers.. and I don't quote know who to turn to for this anymore.. Even the highest rated plumber on checkatrade, who came at a price, didn't pick up something as basic as the cylstat not working..

Any advice on who to contact?? I'm in Hackney, East London..

In the meantime, I feel at this point the best thing to do is to get your valuable help and perhaps pass that information on to whoever I will be able to get in, in the hope it will help him actually solve this saga of an issue..

On that note, would you mind sharing where is that boiler link you mentioned, and what's it called officially?


Many thanks!

You want a competent Electrician to check the electrical side of things

 

[diditrain]

Hi diditrain

Thanks for your input!Sounds like this could be the case..
And yes, the pump is built into the boiler.
At the moment, when on, the heating LED is blinking and the pump is constantly on (I make sure to switch off the boiler after I don't need it).

I'd love to get someone competent in to solve this all asap, but as mentioned above, I've recently had some costly and unsuccessful experience with plumbers.. and I don't quote know who to turn to for this anymore.. Even the highest rated plumber on checkatrade, who came at a price, didn't pick up something as basic as the cylstat not working..

Any advice on who to contact?? I'm in Hackney, East London..

In the meantime, I feel at this point the best thing to do is to get your valuable help and perhaps pass that information on to whoever I will be able to get in, in the hope it will help him actually solve this saga of an issue..

On that note, would you mind sharing where is that boiler link you mentioned, and what's it called officially?


Many thanks!

Do you have any photos of how it is connected inside the boiler?

 

[dfreitag]

You want a competent Electrician to check the electrical side of things

I actually also had a sparky over, too..
a recommended one from my builder..
he told me to change a perfectly working motorised valve..

 

[dfreitag]

Do you have any photos of how it is connected inside the boiler?

Of course. And happy to take more if needed - just let me know..

I can see a dangling black cable again.. and nothing on 3 or 5.. and no bridge anywhere..?

See below!

 

[dfreitag]

It would likely be in RT terminal and jumping from the line conductor where the power connects to the boiler (X1 on the PCB). The manual for your boiler isn't particularly clear.

Sorry, but I'm having trouble finding X1

Also, please see actual connection photo in my previous post above - from my layman point of view the connection to the RT seems incomplete..?

See below PCB taken from the manual

ALSO see below diagram as shown in manual for System Boiler - there is a bridge b/w 3 and 4... which mine doesn't currently have..

 

[Aaron b]

Do you have a photo of the label? The manual looks different to the photos. Has the system ever worked? There's a lot of flux on the PCB I assume it has been repaired.

 

[dfreitag]

Do you have a photo of the label? The manual looks different to the photos. Has the system ever worked? There's a lot of flux on the PCB I assume it has been repaired.

sure - do you mean the boiler label (below)?

I WAS TOLD THIS PCB IS NEW!! I paid £250 for it... did the guy rip me off bringing me a used one??