Heating Wiring Problem - cylinder thermostat not working

[diditrain]

Right. So measured between the blue (N) and grey wire (4) on the PCB - and it's always 244V

Even when you have turned your heating and hot water to the off position?

 

[dfreitag]

Even when you have turned your heating and hot water to the off position?

Yes - heating and hot water being off (on the Nest)!

 

[diditrain]

Yes - heating and hot water being off (on the Nest)!

I would now test between neutral and brown of both of your zone valves when heating and hot water is still in the off position. Hopefully you won’t have 230 volts there. I would then separate the oranges on your zone valves and measure between neutral and each of the oranges in turn to see if one of your zone valves has an issue. Could be a micro switch issue In one or both of your zone valves.

 

[dfreitag]

I would now test between neutral and brown of both of your zone valves when heating and hot water is still in the off position. Hopefully you won’t have 230 volts there.

I have 244V

I would then separate the oranges on your zone valves and measure between neutral and each of the oranges in turn to see if one of your zone valves has an issue.

They both have 244v



any ideas?

 

[diditrain]

I have 244V

They both have 244v



any ideas?

If you have 244v between neutral and the terminal where your brown of the zone valves are connected in your wiring centre, when the heating and hot water are in the off position, then you have a problem possibly from the nest end.

 

[dfreitag]

If you have 244v between neutral and the terminal where your brown of the zone valves are connected in your wiring centre, when the heating and hot water are in the off position, then you have a problem possibly from the nest end.

I see...

So it could be the Nest's fault after all? (I spoke to Google who wants a "diagnostic" in order to send a replacement..)

Assuming you have seen the photo of the cabling at Nest? That seems correct?

Many thanks for your help!

 

[diditrain]

I see...

So it could be the Nest's fault after all? (I spoke to Google who wants a "diagnostic" in order to send a replacement..)

Assuming you have seen the photo of the cabling at Nest? That seems correct?

Many thanks for your help!

You shouldn’t see 230v between neutral and brown when your heating and hot water are in the off position.

 

[dfreitag]

OK, so I checked again (my heart sunk before)

and

b/w Neutral and Brown on both ZV = 0v

b/w Neutral and Orange on both ZV = 244v

All while heating & HW OFF


Apologies, about the wrong info earlier...

 

[Aaron b]

I would remove the permanent live from the valves by disconnecting the orange from the top of 11 and move it to the spare of 5. The spare black looks like it goes to the boiler. I'd connect that to 5 in the junction box and connect the black to 3 in the boiler.

 

[diditrain]

OK, so I checked again (my heart sunk before)

and

b/w Neutral and Brown on both ZV = 0v

b/w Neutral and Orange on both ZV = 244v

All while heating & HW OFF


Apologies, about the wrong info earlier...230v should only be present between neutral and orange when you select either heating or hot water after the valve has motored open

 

[Aaron b]

If you look at the side of the valves there's a manual override. When it's energised you will see it move. You can force it on by pushing it to the open position and holding it up while it tries to close on the spring.

If they are both operating as expected mechanically and you are getting voltage on the orange with the valve in the closed position you have a faulty auxiliary switch which might have been what the electrician was referring to.

 

[davesparks]

one like this?

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www.amazon.co.uk

No, I wouldn't trust that anywhere near mains voltages.

 

[dfreitag]

I would remove the permanent live from the valves by disconnecting the orange from the top of 11 and move it to the spare of 5. The spare black looks like it goes to the boiler. I'd connect that to 5 in the junction box and connect the black to 3 in the boiler.

Thanks for the instructions!

Just to make sure I don't misunderstand please see photos below - can you please confirm?

Many thanks!

 

[dfreitag]

If you look at the side of the valves there's a manual override. When it's energised you will see it move. You can force it on by pushing it to the open position and holding it up while it tries to close on the spring.

If they are both operating as expected mechanically and you are getting voltage on the orange with the valve in the closed position you have a faulty auxiliary switch which might have been what the electrician was referring to.

Hmm
Apologies, but I don't seem to quite understand what to do..


First of all, have I understood the below correctly?

HW&Heating OFF > ZV are energised & therefore closed

HW&Heating ON > ZV are "loose" & therefore open


Should I manually open them while the HW&heating is OFF? And what should I do then?


Quick reminder

• I was getting Voltage when HW&Heating is OFF (BEFORE changing the cables up according to your latest advice)
• I've confirmed that when HW&Heating is ON that the pipes heat up next to both ZV - does this mean they work correctly?
  [*]Upon the advice from the sparky I had over, I recently had the HW ZV changed (though only the motor, no the pipe).
  

Sorry for the "barrage"..

Many thanks again!

 

[brianmoooore]

In its rest position, a zone valve does not allow water to flow through it.
Applying 230V across the blue and brown wires opens the valve, so that water can flow, and also closes a switch between the orange and grey wires.
There is no electrical connection between the brown/blue wires and the orange/grey wires.
The power to the brown and blue wires should be controlled by the heating control system - thermostats, programmer, Nest, etc.
The boiler and pump should be controlled solely by the orange and grey wires, with no direct connection to the afore mentioned control system.
The boiler may also have a permanent live feed, which it uses to power the pump for a short while after the boiler has shut down, to prevent local overheating in the boiler.

 

[Aaron b]

Just to make sure I don't misunderstand please see photos below - can you please confirm?

Yeah that's what I was proposing. You would be removing the switch from the permanent live in the junction box and using the one in the boiler instead.

 

[dfreitag]

In its rest position, a zone valve does not allow water to flow through it.
Applying 230V across the blue and brown wires opens the valve, so that water can flow, and also closes a switch between the orange and grey wires.
There is no electrical connection between the brown/blue wires and the orange/grey wires.
The power to the brown and blue wires should be controlled by the heating control system - thermostats, programmer, Nest, etc.
The boiler and pump should be controlled solely by the orange and grey wires, with no direct connection to the afore mentioned control system.
The boiler may also have a permanent live feed, which it uses to power the pump for a short while after the boiler has shut down, to prevent local overheating in the boiler.

Thank you for clarifying, Brian!!

So I had it all wrong!

 

[dfreitag]

OK, so

I followed Aaron's instructions - and the boiler still fires up immediately - with HW&heat OFF.

Then I check voltage to ZV's again

with HW&heat OFF > 244V

with HW&heat ON > 0V


Is it me, or should it be the other way around??

 

[kropaske]

Before you go any further with this make sure you have the legionella prevention switched off in Nest settings as having this activated even with HW an CH in off boiler can kick in

 

[dfreitag]

Before you go any further with this make sure you have the legionella prevention switched off in Nest settings as having this activated even with HW an CH in off boiler can kick in

thanks for the heads up
I switched this off about a month back, when on the phone with Google..

 

[davesparks]

Before you go any further with this make sure you have the legionella prevention switched off in Nest settings as having this activated even with HW an CH in off boiler can kick in

I wouldnt advise turning off legionalla prevention quite so readily, it exists for a good reason.

As long as hot water is scheduled to be on continuously for 2 or more hours once per week it won't activate legionella prevention.

 

[westward10]

@dfreitag this thread is drifting into a step by step guide which the forum generally does not permit and I admit I have let it run as those contributing are knowledgeable people however, the meter you are using is not appropriate for verifying mains voltages which the forum cannot condone. I understand you have spent a considerable amount of money with no resolution but this thread has been running for nearly a week and I would advise you find a competent person to resolve this issue and whilst they are at it install those flexible cables in a professional manner.

 

[brianmoooore]

I would advise you find a competent person to resolve this issue

As I understand it, he's tried this approach five times. It's the 'competent' bit that appears to be the stumbling block.

 

[Aaron b]

OK, so

I followed Aaron's instructions - and the boiler still fires up immediately - with HW&heat OFF.

Then I check voltage to ZV's again

with HW&heat OFF > 244V

with HW&heat ON > 0V


Is it me, or should it be the other way around??

Your wiring should now resemble the s-plan diagram in the nest instructions minus the boiler being called for and not power cycled.

The voltage should only be present on the orange core when the valve is open, the small valves only have a normally open contact the bigger valves also have a white core. Something is amiss there.

The boiler should only run when there is a connection between 3 and 4. If there's nothing connected in-between the boiler shouldn't run. That PCB looked suspect with all of the flux, I couldn't tell if the joints were dry or take a guess at the function of the repaired section from the photo however.

Hopefully you have enough information to get someone to complete the troubleshooting. Good luck with it.

 

[dfreitag]

@dfreitag this thread is drifting into a step by step guide which the forum generally does not permit and I admit I have let it run as those contributing are knowledgeable people however, the meter you are using is not appropriate for verifying mains voltages which the forum cannot condone. I understand you have spent a considerable amount of money with no resolution but this thread has been running for nearly a week and I would advise you find a competent person to resolve this issue and whilst they are at it install those flexible cables in a professional manner.

Hi @westward10

Thanks for the heads up on this. I wasn't aware of any restrictions - apologies if I've broken any forum rules here.

In all honesty, after a lot of unnecessarily badly spent money and disappointment, this thread has been a breath of fresh air, and I'm amazed about how helpful this thread has been for me, plus very thankful to all who have contributed.

I feel I might be just a small step away from resolving this, and I promise that if not, that I will endeavor to seek (another) hopefully competent person to get this over the line. (I would welcome any recommendations on that note - I'm in East London. Checkatrade or even all good builders I know haven't really proven successful..)

In spirit of the above and if it's not too much to ask for, would it be ok to give me just a couple of more days?

I promise not to abuse this, just trying to get to a point where the situation is manageable by anyone coming in - it seems they're all so super busy at the moment, that they don't have the patience to really put in the time..

I'll understand if not possible, and thankful either way

PS. I didn't get that meter from Amazon. I got one from my local PC/electrics shop.

 

[westward10]

No apologies needed but the forum does have a moral code when it comes to step by step advice. Before you employ another person be sure they understand your situation so you are not wasting further expense.

 

[dfreitag]

Hi again

Before we wrap things up completely, I'd love to have your last opinions on what's going on - I hope that's ok.

Also, just noticed another symptom. One of my radiators (the one right above the boiler) is heating up when I get the hot water to heat..

Your wiring should now resemble the s-plan diagram in the nest instructions minus the boiler being called for and not power cycled.

That's really great! Good to know we reached this

The voltage should only be present on the orange core when the valve is open, the small valves only have a normally open contact the bigger valves also have a white core. Something is amiss there.

B/w orange & brown core I still get

when HW&heat OFF > 244V

when HW&heat ON > 0V

I'm sill not quite sure if this is ok - can someone please clarify?

(PS my Zone valves are 2x Danfoss 087N6609 - link to their website here)

The boiler should only run when there is a connection between 3 and 4. If there's nothing connected in-between the boiler shouldn't run. That PCB looked suspect with all of the flux, I couldn't tell if the joints were dry or take a guess at the function of the repaired section from the photo however.

Do I understand correctly - are you saying this was NOT a new PCB? (the guy who installed it claimed it was and charged accordingly..)

Hopefully you have enough information to get someone to complete the troubleshooting. Good luck with it.

Thanks for all your help @Aaron b - much much appreciated!!

---------------------------------

See below latest photo from wiring box

 

[Avo Mk8]

Do I understand correctly - are you saying this was NOT a new PCB? (the guy who installed it claimed it was and charged accordingly..)

Just to chip in to Aaron b's observations:
I think all one can say is that there is evidence of hand repair to a circuit board that was originally reflowed.
In your photo (post 63), midway along the bottom, between the black plug on the two green/yellow earth wires, and the two blue capacitors, you can see four components that have been hand soldered (the joints are convex shiny blobs rather than the concave reflowed original appearance), and there is flux on the board that in a manufacturing environment would have been cleaned off. There's possibly further rework hidden by the connector.
Boards do get reworked sometimes in the factory, but I would expect a better standard, and the flux to be cleaned.
So it seems clear there has been a repair, but by whom and when we cannot say.

 

[davesparks]

Also, just noticed another symptom. One of my radiators (the one right above the boiler) is heating up when I get the hot water to heat..

Is that radiator in a bathroom? It's normal for the radiatot/towel rail in a bathroom to be connected so that it gets hot when either heating or hot water is on. The theory behind this is to allow wet towels to be dried all year round.

B/w orange & brown core I still get

when HW&heat OFF > 244V

when HW&heat ON > 0V

Are you saying you measured that voltage between the brown and orange of the valve?
If that is the case then you would expect to see 0V between them when the zone is on because both wires should be live at that point. But you might also see 0V between them if something is wrong causing both wires to be dead.

When measuring voltage you are measuring the difference between two points and not an absolute value. So if you measure the voltage between two points which are both live at 230V your measurement will be the difference between them, 230V - 230V = 0V

As for a voltage between orange and brown when the zone is off, theoretically there wouldn't be any, but as you have two floating points and a multimeter you might get any reading between 0V and full mains voltage.

 

[brianmoooore]

Is that radiator in a bathroom? It's normal for the radiatot/towel rail in a bathroom to be connected so that it gets hot when either heating or hot water is on. The theory behind this is to allow wet towels to be dried all year round.

This is a common way of connecting bathroom radiators, but the same effect can occur if a common plumbing mistake is made. If a boiler has a single hot water return port, the return from the HW cylinder must tee into the return trunk nearer to the boiler than any radiator. If not, a venturi effect will occur with the cylinder return water flowing past the radiator tee, sucking water from the radiator branch, through the radiator, along the heating feed trunk from another radiator, and from the return trunk where that radiator tees in. This water will be drawn the wrong way along the return trunk, from the cylinder return, so will be hot, and will heat the radiators.

 

[Aaron b]

If this was something I was asked to look at I would check the voltage on the control to the boiler (call for heating), I would prove the function of the boiler using a link between 3 and 4 I would prove be wanting to prove it was off when the link wasn't in place and that it fired up with the link. If not I'd call valiant and speak to there technical dept.

To prove the nest stat I would want to see the valves move. I think you can press the button on the controller to get it to call for heat. The arm moves on the side and I think it goes loose when energised.

To check the connections through the valves I would probe between earth and the orange from the valve in the energised and the de-energised positions. I'd only expect voltage on the orange core when the valve is open.

 

[westward10]

Thread closed. @dfreitag this has been going on for a week with multiple step by step posts which cannot go on. Find a competent heating engineer.

 

[dfreitag]

OK, so after finally finding a competent heating engineer, I though it could be helpful to share the solution!

Thanks @westward10 for temporarily reopening the thread!

Turns out the culprit was the Heating valve, which was faulty and sending a permanent live to the boiler, independently in which position it was on..

By replacing that valve, the issue was solved. (annoyingly a previous contractor had changed the HW valve - so the wrong one)

(Seems quite plausible in hindsight to be honest, but I guess it almost always is afterwards..)

The engineer also re-did the wiring from scratch, and with a rather clean result - please see below photos of all items.


Hope it is of help for someone out there! I'm definitely relieved to have a working HW and heating systems, before winter and those massive bills hit...

All the best
tsomek

 

[littlespark]

Glad its all sorted....

How did this thread have over 2000 views in the space of a month?