Vaillant boiler - what do the buttons do, controlling the boiler, and opentherm

[louis_b]

Hi,

I've got a "Vaillant ecotec pro 28 VUW GB 286/3-3", I think it's around 10+ years old or so. I don't have a user manual, and I can't find one for this model online on any of the "manual websites" on the internet.

The control panel looks like this - see the attached picture.

What do those buttons do? Especially the "plus" and "minus" buttons?

Also - I'm a bit unclear how this boiler works - there is no separate control panel with a timer or anything like that. There are two dials to set CH and DHW output temperature. Say I set the CH dial to 50°, will then the boiler automatically keep the CH water at 50°, and turn on if it falls below 50°, and turn off again when it's reached 50°? So that basically my CH water stays at a constant 50° (that would be quite convenient).

Finally, since this is an older boiler, there isn't by any chance an OpenTherm extension/module for that boiler available, or is there?

Thank you for any advice.

 

[Aquarius]

2006 - 2009/2010 I think these models ran from and to, before they changed the screen. Look at the serial number underneath on the bottom left, the first 4 numbers should help with the age.

The plus and minus do several different things, usually for the engineer rather than end user. Opentherm isn’t compatible, but ebus (Vaillants own smart stuff) is compatible. You really ought to be using a room thermostat rather than the boiler one.

Edit: your manual is still available as a download

 

[Timmy D]

Im not trying to be an bum here but I guess the real question here is for you.

What are you trying to achieve/what has prompted you to look into/try to understand your boiler?

We can then give better advise, rather than you trying to answer your overall question but asking what you think are relevant lead questions.

 

[louis_b]

@Aquarius & @Timmy D Thank you both for the reply! The exact year doesn't matter too much, I was just thinking it might be useful to post it here.
When I press the plus/minus, the boiler is showing some temperatures (and they deviate from what I've set for CH and DHW temps), so I am also curious what those are.

@Timmy - No offense taken, it's a valid question and thank you for asking!
I moved into an old Victorian house in the UK with above-mentioned Vaillant combi-boiler. There is actually a Nest 3rd Gen connected to the boiler (not installed by me) but I want a better solution. The Nest is located in the kitchen, which leaves the rest of the house cold when cooking/baking. Yes I could move the Nest thermostat to another room but that doesn't solve the problem. I want zoning. I want a really comfortable solution where I can easily put different rooms at different temperatures, while also if possible optimise energy-efficiency/energy use a bit. Since there is only one CH plumbing circuit, I figured that there's basically two, well let's say three, solutions:
1) Honeywell Evohome controller plus their smart TRVs
2) Tado controller plus smart TRVs
3) Fit "normal" (non-smart) TRVs to each radiator, then just let the boiler keep the CH water at, say, 55° during 7am-midnight (or even 24/7), and adjust the temperature in each room with the TRVs.

3) is obviously the "least smart" solution but also the cheapest. My question of "If (without any Nest), can/does the boiler just keep CH water at 50° if I set it to 50?", was thus related to this setup - I wanted to know if the boiler has a mechanism to keep the CH temperature at 50°, and only fire if the water temp is below that, and stop if it's at/above 50.

Though I don't mind shelling out the money for a Tado/Evohome setup - I like smart things that make the home as comfortable as possible.

My question about OpenTherm extension for the current old boiler was because both Evohome and Tado support OpenTherm, which would make the heating even smarter and more energy efficient. I don't necessarily want to install a new boiler now so I'd run this setup with the current boiler and then in the future I'd buy an OpenTherm boiler.

 

[Aquarius]

As I said, for controls similar to that of opentherm, you’d need Vaillant controls. There’s also the Drayton Wiser kits, smart trv’s/room stat and hub, have you looked at these?

Currently your Nest will be working as an expensive (paid by other person) digital on/off switch, with a fancy app and wi-fi. Modern condensing boilers are designed to be more efficient with lower flow and return temperatures, so setting the boiler at 50 may help achieve this, it may not. Balancing of the system usually plays a part.

 

[Timmy D]

So, you’re unlikely to save much if any money by upgrading the controls. If that’s the only goal, then the money will be better spent on reducing your properties heat losses.

Now spending it for increased comfort, I understand.

The two dials regulate the heat in 2 separate areas of your boiler.

1. The heating temp. This regulates the temp of the heating water supplied to your system. This temp would ideally be set so that the return temp is below 54c to allow the boiler to condensate during use.
If the return temp is higher, the boiler doesn’t condensate and you lose any condensate efficiencies.
Once the system is commissioned/balanced, you shouldn’t really need to change this temp. The boiler regulates the burner to keep the temp at what it’s set at.

2. Domestic hot water temp. This is the temp of the water supplies to your hot water taps and can be adjusted to suit your needs.

That covers your dials and is about all you should really need to know/adjust on the boiler itself.

A bit of info in case you’re wondering. First 2 numbers of serial code should be “21” indicating it’s a uk model.
Third and forth numbers indicate year of manufacture.

Vaillant’s Opentherm equivalent is ebus.

Your manual can be found here.

For more control over individual rooms, you’re right, you either need manual or smart trv’s.