Vaillant Turbotec Plus heating not working

tatopane · 4 Jan 2025

Hi Friends,
I have a problem with my boiler that I've been unable to solve in the last 3hs. I hope you can help me.

My setup:
Family house, with Vaillant Turbotec Plus boiler + one VRT 230 thermostat

Context:
It's winter (with temperatures between -1 and 11ºC in the last week).
I've been far from home for the last 3 weeks. During this time, the heating was set to OFF but the boiler was ON during this time.
When I came back home the boiler was low in pressure (0.5bar), which I re-filled to get it to 1-1.2 bar.
I've purged all water radiators in the house today.

The problem:
The hot water system works perfectly, but the heating system is not working at all (it used to work before leaving).

Signals:
The boiler shows status code S.30 (thermostat blocking heating).
If I press the button on the thermostat receiver, the heating SEEMS to try to start, it turns on the icon of the heating pump (altough not the burner), and remains in S.7 (water pump inertia). It never starts the burner, and heating doesn't work. No error code is shown at any time.
I'm attaching some pictures for reference. I've recorded a video as well, that I couldn't attach so sharing in Photos: https://photos.app.goo.gl/UUE3sS5wHskFTLqz5

My current hypotheses:
1. The heating system pipeline frosted and water is not flowing properly
2. The heating system water pump is broken
3. The thermostat is not working properly

Can you please help me understand what is happening?
Thanks a lot in advance!!

Jurassicspark · 4 Jan 2025

The thermostat isn't calling for heat. You can bridge 3 and 4 to get the heating to work but some vaillant's have a drop down door that allows access to the wiring connections without opening up the combustion chamber. I don't think yours is one of them.

Remove the thermostat and send the wiring behind it.

tatopane · 4 Jan 2025

Thanks @Jurassicspark .

2 follow up questions:

Jurassicspark said:
You can bridge 3 and 4 to get the heating to work

1. Is there a way to remove the thermostat without bridging 3 and 4? (I'd love to find a fix that doesn't involve opening the boiler)

2. Does this problem with the thermostat have anything to do with the fact that I've been out of home for 3 weeks? what could have triggered the issue now if it was working well before?

Jurassicspark · 4 Jan 2025

tatopane said:
1. Is there a way to remove the thermostat without bridging 3 and 4? (I'd love to find a fix that doesn't involve opening the boiler)

Is this a system boiler? Have you got a cylinder?

tatopane · 4 Jan 2025

No. It is a combi boiler without a cylinder

Jurassicspark · 4 Jan 2025

Okay, any external zone valves?

tatopane · 4 Jan 2025

The only valves I'm aware of are those of input/output of the heating system water (those at the two sides of the picture).
These were not touched before/after the problem

Jurassicspark · 4 Jan 2025

Remove the thermostat and send a picture of the wiring at the back.

tatopane · 4 Jan 2025

This is the wiring.
3,4,5 are coming from the receiver of the thermostat VRT240f

cross thread · 4 Jan 2025

Power off remove 3 and4 and make safe ,link 3/4 on terminal s ,power on and see if heating works

tatopane · 4 Jan 2025

Yes! It worked!!

Before your messages I didn't have the courage to open the electric board of the boiler
You are awesome!

Now, can you please help me figure out:
1. What thermostat should I buy? (Considering my boiler has 3 cables for it, and most new boilers only have 2) Ideally a wifi one

2. While I buy the thermostat, can I add an interruptor (open/closed) to the bridge so to control heating manually?

Thanks again!!

Jurassicspark · 4 Jan 2025

tatopane said:
1. What thermostat should I buy? (Considering my boiler has 3 cables for it, and most new boilers only have 2) Ideally a wifi one

Many options are available but I'll recommend Hive or Wiser. Wiser is easy to use and you are able to add wireless TRV's to the radiator, along with smart plugs.

tatopane said:
While I buy the thermostat, can I add an interruptor (open/closed) to the bridge so to control heating manually?

Not sure what you mean by this, you can press the button on the receiver to turn heating without using the app.

Jurassicspark · 4 Jan 2025

If you don't want to change the thermostat, you can check why the existing one is not firing the boiler. Maybe a reset or a loose wire behind it? Have you got a multimeter?

tatopane · 4 Jan 2025

you can press the button on the receiver to turn heating without using the app.

At the moment my best guess is that the receiver is not working properly (bc I tried operating it manually with the remote off, and it didn't work).
So when I did the bridge between 3-4, I disconnected the receiver, because it was generating the malfunction of the system.

Now heating works but I can't turn it off. So I'm planning to buy a new thermostat+receiver.

tatopane · 4 Jan 2025

Ok, so to close the thread, I want to thank @Jurassicspark (huge kudos to you!) and @cross thread for your contributions.

I concluded the thermostat receiver is not working properly. After doing the bridge, and willing to add a manual control to it, I remembered I had a never used wifi switch bought in AliExpress ~4yr ago. I connected it to the bridge in the same way the receiver was connected, and magically I got the heating system to work with the "smart life app".

Next steps for me: now that I added my heating on-off to the smart life ecosystem, I'm searching for options (thermometers or thermostats) to trigger via automations the smart switch.

It's a happy ending and turned out to be a lot better than I initially expected. Also, saved a ton of money.
Thanks again to both Jurassicspark and cross thread

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Vaillant Turbotec Plus heating not working

tatopane

Attachments

Jurassicspark

tatopane

Jurassicspark

tatopane

Jurassicspark

tatopane

Jurassicspark

tatopane

cross thread

tatopane

Jurassicspark

Jurassicspark

tatopane

tatopane

DIYnot Local

Similar threads