Vaillant EcoTec Plus 831 - Heating flow temp remains at 50 degs

[Kuchars22]

Hi,

In an effort to raise temps to at least 20 degs in the home, I have increased the target flow from 75 to 80 degs with no success, and the actual "heating target flow temp" value remains at 50 degs.

To give you an idea, from 11 degs it has taken so far 9 hours just to 15.5 degs. Have also tried changing the pump from Auto (which was reading a value of 15%) to 100%. The Partial Load was originally set to 24kW. Have now set to 14kW to see if this makes any difference.

3 bed end terrace w/ solid walls, insulated loft, with 9 rads, mix of double and single all with TRVs set to max open. I have a Hive thermostat installed this summer too, replacing the VRT unit before this, and the Hive is working fine.

Other settings:

Pump overrun: 5 mins
eBus controller target value (if connected): 50 degs
Control type: flow
Pump mode: Eco
Return Value: 47 degs
Pump operating mode: Auto heating; DHW stage 2
Bypass valve position: unknown

Assuming all calculations for rads are suitable, generally how can one increase the target flow rate on the boiler? I am not a boiler/heating engineer, so I appreciate I may not have given you all the information that you need (if you need specifics do let me know) and I also understand that there are other ways to improve efficiency other than from the boiler, but this is a question about adapting the boiler itself.

Heating comfort was pretty much better than this year, so I was wondering of the new Hive controller has any contribution to this issue.

Thanks

 

[oldbuffer]

What controls do you have on the boiler?

Is weather compensation fitted, and if so what is the heating curve value set to?

 

[Kuchars22]

What controls do you have on the boiler?

Is weather compensation fitted, and if so what is the heating curve value set to?

The only controls is the + and - buttons, as well as the Back and Cancel buttons. Forgot to mention that the left side of the display shows the flame burner graph, and it always stays way down below and never increases, almost at the minimum level. Cannot remember what level this was at when we had the VRT fitted. When should this be increasing?

No idea about whether a compensator is fitted - it was a VRT350f, but the wireless performance was crap, and as we often get power surges, it would often lose all connections to the boiler and everything would reset including heating temps, schedules, etc, so we ditched this and got a hive thermostat.

Using a digital thermometer, I'm measuring avg 41-45 degs on each of the rads. Perhaps it's just the insulation of the walls, though I'd expected the room to be able to heat up much quicker - it has yet to even touch 20 degs today (3 degs today)

 

[jackthom]

is the VRT350f still connected to the boiler?

 

[Kuchars22]

is the VRT350f still connected to the boiler?

No. It wasn't wired to the boiler if that's what you mean. It was freestanding in the lounge and communicated to the boiler via wireless. Was considering having it wired to the boiler before we opted for Hive

 

[jackthom]

Was the wireless receiver unit removed from the boiler.
TBH I don't know enough about these systems to be sure but I'd be wary of leaving in a unit which could still be sending ebus control signals to the boiler.

 

[Kuchars22]

Was the wireless receiver unit removed from the boiler.
TBH I don't know enough these systems to be sure but I'd be wary of leaving in a unit which could still be sending ebus control signals to the boiler.

Don't know. I took before and after photos when the installer installed the Hive unit.

 

[wannocks]

Is the receiver plugged into the front panel? Should have a green light and a button.

 

[jackthom]

Looks like with newer boilers (after 2012) the receiver unit has been incorporated into the main pcb.

Maybe someone here can shed some light on how to check if it's been decommissioned.

 

[wannocks]

It's a plug in one on all of them. If it's fitted and the light is on it will be trying to control the boiler. It can also go in a box mounted externally and connected to the ebus terminals.

 

[abbadon]

I don't know the answer, but I can see that a link wire/jumper is gone from a 24v terminal in your second picture - anyone know if that's ok for the OP?

I'm guessing that's to do with the previous wireless stat if it was connected to the board elsewhere - and the link enabled it?

 

[Kuchars22]

It's a plug in one on all of them. If it's fitted and the light is on it will be trying to control the boiler. It can also go in a box mounted externally and connected to the ebus terminals.

If you look at the photos I attached earlier, you can see that the pink ebus connector has nothing connected to it. It didn't have anything connected to it before the Hive was installed either.

The receiver light is red. I do recall an option in the Installer Level that the wireless control panel wasn't detected

 

[jackthom]

It might just be plugged into the front of the boiler, under the pull-down panel.

 

[jackthom]

I don't know the answer, but I can see that a link wire/jumper is gone from a 24v terminal in your second picture - anyone know if that's ok for the OP?

I'm guessing that's to do with the previous wireless stat if it was connected to the board elsewhere - and the link enabled it?

Pretty sure the 24V link also has be disconnected for 230V thermostat operation and connected for ebus controllers.

 

[Kuchars22]

That's what I have on the boiler itself. The light is constant red. Used to be green when the remote VRT was used. This is now stored away with the red link cable that was attached to RT 24V.

Just checked and the Option 90,91 and it says that a Digital Regulator is "Recognised" (90), DCF Status has "no reception" (91) if that helps