Vaillant EcoFit Pure 835 Temperature Panel Control

Hello all,

Just moved into a house with a Vaillant EcoFit Pure 835 boiler that is 3-4 years old but the previous owner did not bother to register with Vaillant, so Vaillant says its not under warranty.

I've noticed that despite setting the CH to 60 degrees on the boiler's control panel, the boiler heats to 75 degrees with the radiator LED blinking. The DHW is set to 50 degrees but I am pretty sure the output from boiler is much hotter than that.

Can someone please clarify what is happening here and how can this be fixed?

Thanks.

The vaillant room thermostat may be over riding the set temp to achieve the desired room temp

Which controls do you have?

Thanks for your replies.

I have a wireless room thermostat which is called Vaillant VRT 350F. On this device, I have desired room temperatures set to 18 degrees only when the heating is ON.
I am not aware of any other setting. Kindly advise.

If the room thermostat is responsible, is there a way to take its batteries out and start the CH on the boiler itself after bypassing VRT350F? This can establish if the boiler panel controls are working on their own.

Also, this does not explain why the DHW is so hot!

ksareen said:

Thanks for your replies.

I have a wireless room thermostat which is called Vaillant VRT 350F. On this device, I have desired room temperatures set to 18 degrees only when the heating is ON.
I am not aware of any other setting. Kindly advise.

If the room thermostat is responsible, is there a way to take its batteries out and start the CH on the boiler itself after bypassing VRT350F? This can establish if the boiler panel controls are working on their own.

Also, this does not explain why the DHW is so hot!

Click to expand...

The VRT 350 is capable of load compensation as far as I remember.
That means that it can regulate the boiler temperature by overriding the boiler settings.

Thinking of the room where the VRT is situated:

Is the room reaching temperature quick enough?
Once it is up to desired temp, does it remain comfortable and if so are the radiators still very hot?

It may be that the radiator where the sensor is, is undersized? or could it be in an area/room that never reaches the desired temp for some other reason?

It is difficult without seeing the set up you have but worth a try.

Have you tried siting the sensor in another room/area to see how it performs.

Last Plumber said:

The VRT 350 is capable of load compensation as far as I remember.
That means that it can regulate the boiler temperature by overriding the boiler settings.

Thinking of the room where the VRT is situated:

Is the room reaching temperature quick enough?
Once it is up to desired temp, does it remain comfortable and if so are the radiators still very hot?

It may be that the radiator where the sensor is, is undersized? or could it be in an area/room that never reaches the desired temp for some other reason?

It is difficult without seeing the set up you have but worth a try.

Have you tried siting the sensor in another room/area to see how it performs.

Click to expand...

I have the VRT350 manual somewhere so I will check on this load compensation.

As the thermostat is wireless, it tends to stay in multiple rooms.
The radiator valves in 2 rooms are already closed to conserve energy, but the other radiators are getting hot enough, apart from one that is farthest from the boiler. The twin radiator nearest to the boiler gets very hot very soon.
The balancing on the system is quite bad and I am partially responsible for that, but I never realised that this could lead to boiler overshooting the temperature set at its own panel!

If there is a dummy guide on radiator balancing, please do share. Thanks.

Try to keep the control in one place. Maybe the living room.
Some controls (not sure about yours as we use the sensocomfort now) can be optimising as well as load compensating.
If it is attempting to 'learn' how quickly your property takes to reach a desired temperature, keep moving it won't allow it to work correctly. As I said, i can't remember whether or not the VRT 350 does that or of it just uses load comp.

A week in one place may show a difference. 1.5 meters up and away from heat sources is good.
Failing that, you'll need to get someone out to look at it and balance system.

Vaillant literature is all on their website if you need it.

Last Plumber said:

A week in one place may show a difference. 1.5 meters up and away from heat sources is good.

Click to expand...

Sorry for late reply. This advice did not help unfortunately. The VRT350F has been on a 1.5 meter high shelf for ~3 months and it did not make an iota of difference to temperature or behaviour.

Just had the boiler serviced and the engineer told me that despite the display on the boiler, the water being circulated might be 65 (which is my control panel setting on the boiler). He was clueless when I told him that regardless of temperature settings on the control panel, the radiator always got heated to the same temperature.

There is an option of resetting VRT350F which should lead to installer menu, but the service engineer was not keen on that. I understand that as the VRT550F user manual says that boiler will not fire unless it is setup properly.

Should I focus on getting some help from Vaillant here? Would they even help me as I am not an installer?