Will overvoltage damage circuit boards? (Ed.)

[BadVoltage]

Time for a new PCB then..

That's what I suspected but was holding out hope. Damn. This is going to sting.

 

[Stuckinarut]

View attachment 365994View attachment 365995
The 12v RT is on the top left of the PCB, 240v is on the top right.

Just to add, there is no sign of scorching, smoke, etc on the front or back of the PCB but there is the smell of burnt plastics/electronics.

If that’s how it’s wired, how did you inadvertently send mains voltage to it?

 

[BadVoltage]

If that’s how it’s wired, how did you inadvertently send mains voltage to it?

I replaced the hub with a Drayton Wiser unit and the CH wasn't firing (hot water was fine). After some research it looked like i needed a link between L and 1.

Unfortunately, I'm pretty sure that this sent 240v down 2, which were both connected to the 24v RT and not the 240v RT connections in the boiler.

Honestly, I had no idea 24v was even a possibility here and there was certainly nothing on the Wiser docs that suggested it might be the case.

 

[BadVoltage]

Just to update - I managed to find a new PCB at a nearby merchant, and swapped it in.

I tweaked the wiring in the back plate (moved one of the RT wires from 2 to 1).

NO LINK to L

And it all seems to be working perfectly.

Have booked an engineer to come out and give it a service too.

A £230 lesson.

 

[ericmark]

I got the wrong boiler when I googled, but note

so not sure if the Wiser should use the contacts at all? Should it connect to the little white connector block

on the back of the hub, I am not sure on this as there are more than the OpenTherm options, I know Wiser is OpenTherm, not sure however what your boiler is?

I did watch the instructions video on how to install frankly a bit useless unless the old thermostat used the standard back-plate. My boiler is a 230 volt on/off control, most oil boilers are.

The whole idea of modern gas boilers (not oil) is that they modulate, read that as turn down, there are two ways to turn a boiler down (rather than off/on) one is by the return water temperature the other is using the bus, the whole idea is to ensure the return water is cool enough to gain the latent heat from the flue gases, if not using OpenTherm, then the aim is not to turn the boiler off/on too often, as each time it is turned off and back on again, the boiler software starts again working out the temperature required for the outgoing water, so the incoming water is cool enough to gain that latent heat.

So there is in theory no need for a wall thermostat. The Wiser TRV heads tell the hub to keep the boiler running until all connected heads are satisfied, so in winter the boiler turns down, rather than turning on/off, and the radiators are just warm enough to maintain the room temperature, so there is little or no hysteresis. I use oil so can't use this feature, but using linked TRV's does mean can warm just a bedroom, and I don't have to heat the whole of the house.

Hope your claiming off the installer who got it all wrong?

 

[BadVoltage]

There is an OpenTherm block but I have literally no idea what to do with it and, regardless, my 10 year old boiler is unlikely to have that feature. Again, I've no idea what these Bus connections are for. As a result, I've not touched it.

Re: claiming if the installer - a) I've only been in the house a month, and b) I've given myself a stern talking to (I was installing the Wiser myself).

 

[Stuckinarut]

Hope your claiming off the installer who got it all wrong?

Different thread

 

[Stuckinarut]

There is an OpenTherm block

Ebus - Vaillant and glowworm controls only for modulation

Re: claiming if the installer - a) I've only been in the house a month, and b) I've given myself a stern talking to (I was installing the Wiser myself).

He was getting confused with a similar thread

 

[BadVoltage]

Is it worth getting the eBus connected up?

 

[Stuckinarut]

Is it worth getting the eBus connected up?

It can be. Depends on how long you plan to keep your existing boiler for and if you'd stick with Vaillant/Glow worm

 

[Harry Bloomfield]

Again, I've no idea what these Bus connections are for. As a result, I've not touched it.

Is it worth getting the eBus connected up?

It's a control bus unique to Vaillant, though they did an adaptor which allowed it to connect to a standard bus system, it was never allowed to be sold in the UK.

Worthwhile getting the Vaillant control kit? If you think the investment in the kit, is worthwhile, if your boiler will last long enough, or you would replace it with another Vaillant - yes. The kit makes a great job of precisely controlling the boilers output, to match the load and demand, which itself offers savings in gas consumption, plus the steady heat from radiators, instead of the hot, then cold.

 

[Jurassicspark]

Is it worth getting the eBus connected up?

When I upgraded to Valliant designated controls, the boiler became less "noisy" or at least almost inaudible, at first I thought it wasn't running!

The return on investment will take a while though.

 

[BadVoltage]

It's a control bus unique to Vaillant, though they did an adaptor which allowed it to connect to a standard bus system, it was never allowed to be sold in the UK.

Worthwhile getting the Vaillant control kit? If you think the investment in the kit, is worthwhile, if your boiler will last long enough, or you would replace it with another Vaillant - yes. The kit makes a great job of precisely controlling the boilers output, to match the load and demand, which itself offers savings in gas consumption, plus the steady heat from radiators, instead of the hot, then cold.

Thanks.

The boiler's 8 years old and I'm not wedded to a particular make.

Plus I've just invested in the Wiser kit so wouldn't want to waste that (it sounds like the Vaillant kit would replace the Wiser?).

 

[RandomGrinch]

Plus I've just invested in the Wiser kit so wouldn't want to waste that (it sounds like the Vaillant kit would replace the Wiser?).

Yes, the Wiser would usually be replaced. However, as Harry has mentioned...

It's a control bus unique to Vaillant, though they did an adaptor which allowed it to connect to a standard bus system, it was never allowed to be sold in the UK.

The Vaillant VR33 OpenTherm adapter would be unsupported, but is available.
If bought from a continental supplier, the prices are reasonable (whereas eBay are scalping)...

Vaillant VR33 OpenTherm module 0020017895 - cvonderdelen Hartog

www.cvonderdelenhartog.nl

As you already have the Wiser, stick with it. It is a smart, load compensating stat that will help improve efficiency over standard on off stats, if not quite up to the values of a fully modulating controller.
If you do want to look at an OpenTherm solution, there are a few threads on here regarding the VR33.

 

[Harry Bloomfield]

Plus I've just invested in the Wiser kit so wouldn't want to waste that (it sounds like the Vaillant kit would replace the Wiser?).

I think the difference might be, that the Vaillant kit, is able to tell the boiler when, and exactly how much to modulate by - so as to just hit the set temperature, when bringing the house to a new temperature. Then once at temperature, can fire the boiler just long enough and at a modulation level, to precisely match the ongoing need for heat. Your Wiser, will just demand boiler on, or of, and leave the modulation for the boiler to work out..