Have I blown my boiler electronics?

[Dan8322]

OK - I might cross-post this into DIY Disasters, but I'll start here.

I wanted to fit a Hive 2 controller to my Vaillant EcoTec 28, to replace the Danfoss RETB+RF that's fitted there. I had accidentally bought the Heating + HW Hive, despite only needing the heating control on my combi boiler. I googled, and it seemed to be OK, so I went ahead.

Now, the Danfoss backplate is compatible with the Hive one, so you can leave that in place. Before I did, I had:

L & N on the left
Grey cable to 2 (Common)
Black cable to 3 (Heating on)

So, I moved the black cable to 4 (Heating on for the Hive), and put it back together.

Put the Hive controller on, turn it all on, and nothing. Check - fuse is blown. Ah.

Checking the website, I realise I should also have moved the grey cable from 2 (common) to 1 (HW off); the Hive Heat+HW doesn't have a Common terminal.

Do that - turn it back on. Nothing. Check. Fuse blown again. OK.


Alright - so I've rolled back, put the Danfoss back on, turned it all back on with a new fuse, and... nothing. Troubleshot the thermostat, and the thermostat is calling for heat, and the RF controller next to the boiler has a light under CH1 which goes on and off as I turn the thermostat up and down, so it appears that is also demanding heat.

However, the boiler isn't listening - it shows an S30 code (no demand from external controls) if I check. I currently have it on manual mode to keep the house warm.


The question is - have I just blown my lovely 1yo combi boiler's electronics? The controls, panel, etc. are all working, but it just doesn't seem to be demanding heat, and I haven't touched any other wiring than at the panel, which is back where it was.

Is there any other way to check that the electronics are working correctly?

Thanks!


Dan

 

[Dan8322]

Just an update - I removed the controller's panel and connected 3 & 4 together; the boiler still doesn't respond and still shows S30.

 

[jackthom]

When you say "manual mode" do you mean setting the boiler timer to permanently ON and does the boiler then deliver heating ?

If so, that is OK and is likely the only way you can allow the Hive to take control of the heating schedule.

 

[Dan8322]

The timer on the boiler was always on; what I did, was press the two buttons at the bottom of the panel together in order to override the external control and turn the heating on continously.

 

[Agile]

Just an update - I removed the controller's panel and connected 3 & 4 together; the boiler still doesn't respond and still shows S30.

Is that on the PCB inside the boiler?

Tony

 

[Dan8322]

No, I haven't opened up the boiler yet. That's on the thermostat receiver mounted on the wall next to the boiler.

 

[muggles]

It depends on how your boiler is wired. If it's wired to the low voltage side and you've just fired 240 volts into it then it's very likely to be bu99ered. It may be possible in this instance to rewire to the 240v side to get it running again, but there's no guarantee it'll work and you'll need a Gas Safe Regd engineer to do it as you shouldn't be removing the cover on this boiler yourself. Tell him to bring a new board with him just in case

 

[Dan8322]

Yeah.. well, I've not touched anything in the boiler, so I shouldn't have changed it from low to high voltage or vice versa. The fact it blew the main socket 3A fuse made me think it's connected to the high voltage side.

 

[stem]

You may well have damaged the boiler. The Hive Single Channel version you should have used has isolated switching contacts that are potential free and can be used to switch any voltage. The Dual Channel Version of the Hive doesn't have a potential free contact, it is connected internally to mains voltage 230V

As well as 230v, I believe your boiler can use only 24v for its room thermostat, and if so, and you have just connected it to 230v via the Hive, you may well have fried it.

I'm not a Vaillant expert and there are lots of variants, but if you have your manual you should be able to check.

 

[Agile]

This may demonstrate that, attractive as it seems, it may not always be that simple to fit a Nest.

Most installers still use the 230v connections on boilers. As far as I know your boiler will have both 230v and 24v stat connections for the installer to select which to use. I don't know why they like the 230v as that's potentially more dangerous having 230v on controls and cabling. I suppose old habits die hard.


Tony

 

[Dan8322]

It sounds like I'll have to take the cover off to have a look. I had assumed it would (and should) have been pretty simple wiring, something I'd done before with a Honeywell thermostat a while ago, but it sounds like the Single vs Dual Channel differences tripped me up.

I'll take a look which side it's wired to. If so, I guess I should consider myself lucky the boiler can still deliver heat.

 

[muggles]

I'll re-iterate...you shouldn't remove the cover of your boiler unless you're Gas Safe Registered. It forms the safety room seal on your boiler

 

[Agile]

I'll take a look which side it's wired to. If so, I guess I should consider myself lucky the boiler can still deliver heat.

But you said it was showing an S30 and so not delivering any heat.

It is irrelevant which Hive you have.

What is relevant is if the boiler is connected for low voltage controls.

Something a professional installer should be doing ( if he wants to avoid having to pay for a new boiler PCB ).

As said, you should not open the boiler!

Tony

 

[stem]

I have found this circuit for an EcoTEC. If it corresponds to your version it will enable you to identify if your Danfoss thermostat was switching 230v or 24v by the terminals it was connected to.

 

[Dan8322]

Thanks! Yes, again, I've not removed the boiler cover to check which side it's on, and I think it's better not to today judging by my day so far. Lack of sleep doesn't help my judgement right now.

I would have taken a multimeter to it first to understand what was going on, but we've just moved and it's packed away.