Weird behaviour Vaillant 470f system

[Harry Bloomfield]

Two issues and I have had this system installed now for 18 months...

If it is set for a night set back room temperature of for instance 13C and the actual temperature is 18C and it never falls below that - when it is cold outdoors in can sometimes fire up the boiler quite briefly. This usually happens in winter, never summer. It has an outdoor sensor, might that have something to do with it?

If I have the night setback set at 13C day temperature 18C and override either of those temperatures by turning its knob to a higher temperature, it gives a choice of pressing OK to make the new temperature permanent, or not pressing OK which I assume should have it go back to the programmed temperatures, once the present heating period ends. It doesn't say when it should go back to normal programmed temperatures in the manual, I have assumed that it ought to work that way.

Except it doesn't - Change the desired temperature, don't press OK and often it makes the new temperature its permanent temperature until I spot it and change the desired temperature back again.

 

[The831Bunny]

There are three choices of how the 470 references temperature. In the installer menu>system configuration you need to check the room temperature control is set to ‘thermostat’, NOT ‘without’ or ‘thermostatic/modulating’, the heat curve is 2.4 (if you have radiators), and summer offset is -1C. Set back temperature should be 12-15C, if your property is poorly insulated and drops below 15C at night, you can lower the set back. Saying that, set back is designed to stop the property cooling too much when the heating is off, so making the system work less hard (longer) to put heat back in when you need it.

In AUTO adjusting the desired temperature on the 470 and NOT pressing the OK means the new temperature runs till the next scheduled change in the program. Pressing OK makes this new desired temperature operate every time the heating is ‘on’.

There may be a few more settings to check, but let us know your outcome.

 

[Harry Bloomfield]

In AUTO adjusting the desired temperature on the 470 and NOT pressing the OK means the new temperature runs till the next scheduled change in the program. Pressing OK makes this new desired temperature operate every time the heating is ‘on’.

There may be a few more settings to check, but let us know your outcome.

It is definitely, at least sometimes, storing my adjustment. I thought at first someone else was adjusting the temperature and pressing OK, but I have seen it store it when I have been the only one in the place for a weekend. I a now trying to remember to press Menu, then checking the Desired temperatures - to see if it has stored the temporary change.

It could take a while, but I will report back..

 

[The831Bunny]

As the 470 has a 7 day program, check each day to see if there are no unwanted times programmed. In auto the desired temperature is indicated on the bottom of the screen. Also check the wireless strength in the installer menu. Anything 4 or below maybe causing your problems. Is the receiver plugged in the front of the boiler, and behind the drop down flap?

 

[Harry Bloomfield]

As the 470 has a 7 day program, check each day to see if there are no unwanted times programmed.

I have already checked that, it is the same for every day and shows the moon and sun symbols on screen, at the correct programmed times.

In auto the desired temperature is indicated on the bottom of the screen.

When the boiler has fired up briefly, when it should not have fired up, I compare the desired to actual room temperature on the display. Actual is always higher by several degrees. Unless the weather is extremely cold, even without any heat input overnight, the indoor temperature never falls below 17/18C. With night setback at 13C, us in bed - I hear the tick, tick, tick of the pipes as the boiler fires up and the radiators warm up slightly, but not enough to make much difference to the room temperatures. Dash down to look at the 470f's display and the room temperature will be much higher than the desired, so no reason at all for the system to have fired up.

Its an open vented system and HW is set to come on each day from 16:00 to 17:00, so there is hot water ready for dinner. If someone takes a bath, then the 470f is set to HW Boost. So the middle of the night ticking of the boiler heating up, is not the boiler heating up the HW.

As said, it only seems to happen during the winter - which is why I was wondering if it might be something to do with its outdoor temperature sensor. My guess - the 470f sees the outdoor temperature fall, assumes the indoor temperature will also fall, so it fires up the heating in anticipation of that happening.

Also check the wireless strength in the installer menu. Anything 4 or below maybe causing your problems.

It has always shown full strength, apart from for the outdoor sensor. 470f is mounted just outside kitchen door in the hall, boiler at far end of kitchen.

Is the receiver plugged in the front of the boiler, and behind the drop down flap?

Receiver is plugged into front of boiler. From memory - The receiver forms part of the front panel, rather than being behind a flap.

 

[flycop2000]

Hi Harry,
I also have a similar problem. I have just upgraded my heating controls to the wired VRC700 (installed in boiler front panel) and some Ambisense TRV's. I get up early in the morning for work and some of the radiators are hot, way above the setback temp.
I'm interested to see a solution for this.

 

[Harry Bloomfield]

I also have a similar problem. I have just upgraded my heating controls to the wired VRC700 (installed in boiler front panel) and some Ambisense TRV's. I get up early in the morning for work and some of the radiators are hot, way above the setback temp.
I'm interested to see a solution for this.

Do you have an outdoor temperature sensor fitted?

So like me, you are seeing/ hearing the boiler run, with the room temperature higher than the 'Desired', as shown on the 470f display?

I am tending towards thinking that the 470f is seeing it cold outdoors and is deciding based on that, that the house needs some heat to be added to compensate. My radiators don't usually get hot, more often when this unnecessary firing happens, they get just slightly warmed.

I have contacted Vaillant UK Technical, but they have been unable to offer any explanation for the behaviour other than to offer to send an engineer out to investigate. It seems that Vaillant maybe do not know much about the systems they sell, because it is very obviously deliberate designed behaviour of the system rather than an actual fault.

 

[flycop2000]

Hi Harry,
I have a wired outdoor sensor. I previously had the original weather compensator VRC430, I just used the same sensor which did read the temp quite accurately comparing it to my weather station. I think I'm correct in saying that when the VRC700 is plugged into the boiler it disables the built in thermostat? I am using some VR50 TRV's which I was led to believe that they would control the requests for heat from the boiler.
I hope we get a solution for this soon as it's driving me nuts

 

[Harry Bloomfield]

I hope we get a solution for this soon as it's driving me nuts

My outdoor displayed temperature (wireless) is also accurate. Likewise, it drives me nuts too, during the winter - the creaking has the system warms up during the night time. No doubt the extra, unnecessary firing causes extra wear and burns unnecessary gas for no purpose.

 

[flycop2000]

Harry are you using the VRC700 app to control things?
What settings do you have in the VRC700? In my case I think it's something in the VRC700 settings conflicting with the Ambisense settings in the App?

 

[Harry Bloomfield]

No, I am just using the settings provided on the 470f's display. My system is :-

Ecofit Pure open vented boiler heat only

VR65 E-Bus Control centre

VRC 470f Display / control

Vaillant Wireless outdoor temperature sensor

SDM 1901 3-port valve

Grundfos Alpha+ pump.

 

[flycop2000]

I'm using an Ecotec plus 831. wired VRC700, VRC920 gateway, VR50 TRV's

 

[Harry Bloomfield]

I caught the 470f yesterday, confirming what I thought I was seeing it doing.....

Daytime Desired Temperature was set and had been stored and set to 16C for several weeks.
It became a bit chilly in the house yesterday afternoon (19C), so I nudged the temperature up to 22C at 15:00 without pressing OK to store the temperature.
Heating fired up, went off at 16:00, to heat the water in the cylinder - it does not do both HW and CH at the same time.
SWMBO arrived home 18:00 hot and bothered, so she left the back door open, so I turned the Desired back to 14C without pressing OK. I checked the stored Desired temperature, which had stayed put, as it should, at 16C

Dinner had, washing up done, I decided to have a bath, so set the 470f to 'Cylinder Boost' to make sure there was a full tank of hot water.

Had my bath and half an hour later, noticed the heating coming on (after it had finished replenishing the HW I had used in the bath). Checked the Desired temperature it was 22C. Checked the Desired temperature in the program, that had also gone up to 22C, so I changed that back to 16C.

Just to be clear - there is a permanently stored Desired temperature for Day and one for Night setback. Aside from these stored temperatures, you can change the Desired temperature temporarily, without storing it by just turning the dial without pressing OK. Pressing OK stores it as a permanent setting - or at least that is what is supposed to happen.

 

[The831Bunny]

Two things could be happening. It’s difficult to diagnose not being in front of the equipment and doing a full diagnostics.

The heating zone valve is passing to heating when ‘off’ and HW is operating.

The wireless signal is poor or there is a fault at the receiver, as a lot of data on Vaillant RF controls is kept at the boiler and communicated to the stat.

BTW, it is false economy when using a VR10 with a UV cylinder to heat HW ‘Ad hock’. The boiler has an extremely complex software routine to load HW cylinders. You will always need HW later, so time the HW to be off say 11pm-5am, on the rest of the time. You’ll be surprised how little the boiler is on to reheat the cylinder.

What were your settings re thermostat/modulating/none?

 

[Harry Bloomfield]

The wireless signal is poor or there is a fault at the receiver, as a lot of data on Vaillant RF controls is kept at the boiler and communicated to the stat.

BTW, it is false economy when using a VR10 with a UV cylinder to heat HW ‘Ad hock’. The boiler has an extremely complex software routine to load HW cylinders. You will always need HW later, so time the HW to be off say 11pm-5am, on the rest of the time. You’ll be surprised how little the boiler is on to reheat the cylinder.

I was aware the boiler stores some of the data, but not clear on what exactly. The manual hints at the VR21 outdoor temperature sensor, also being able to receive the radio time code, which it uses to keep the system's time accurate. So far as I was able to tell, it doesn't - I have to set the real time manually each time the boiler is turned off and back on. The boiler to 470f signal is rock solid/ 470f is not far from the boiler almost within LoS of it. I notice the 470f can sometimes wake up the display whilst it still has old data showing and can take a second to update the display to current data.

We don't need much HW during the day and when we do, it is hot enough for our needs until the evening washing up, so I have it set to be on 16:00 to 17:00 to just top the temperature up for that. We take a daily electric shower, but maybe a bath once a week - so we use the HW Boost for that, as needed, left on boost until the used bath HW is replaced in the tank. I'm not convinced that having HW on throughout the day, is worthwhile for our circumstances, but I will give it a go.