w.Intercom = i;img.ProfilePhoto.ProfilePhotoMedium { padding: 10px; }Tado V3, Vaillant ecoTEC plus 630, VR65, eBus, 3-way valve, hot water sensor — tado° Community

Tado V3, Vaillant ecoTEC plus 630, VR65, eBus, 3-way valve, hot water sensor

DJI
DJI ✭
in General Questions & Topics

Hi,
I've successfully followed the many discussions about implementing eBus on my very old UK Tado V3, Vaillant ecoTEC 630 and 2nd hand VR65, and it seems to be working (I ask for heat to the radiators, and it does; I ask for heat to the hot water cylinder, and it does). Many thanks to all the insights on this forum.

For anyone interested, I don't have 24V = RT pins on my PCB, so I couldn't short them; I did short pins 3 and 4 on the relay control contacts.

2 questions arise:

I have a Drayton 3-way/ mid-position valve which selects hot water flow to the radiators, the hot cylinder, or to both.
I can use d.70 to select Normal (which seems to be radiators or hot water, but not both) or Centre Position (which seems to leave it in centre position a lot). I've seen @autolycus comment about heating working only when there was no demand for hot water: my system seems to 'hunt' when I'm asking for both hot water and heat when configured in Normal, but I'm not clear whether it's working or not. So I'm struggling to decide which setting is 'correct', and would appreciate inputs from anyone else who has this configuration.

I have a vented hot water cylinder with switched thermostat, but I've seen discussion about replacing the thermostat with a thermistor - I think Vaillant VR10 connected to the VR65 NTC pins. This would allow the desired hot water temperature to be set from Tado. Other than this, are there any other benefits from switching to a thermistor?

Thanks again for all the information here - it would have been a nightmare without you.

Comments

  • Montage
    Montage ✭✭✭

    I don’t have any of that stuff, but my general thoughts.

    You want the 3 port to avoid sending the boiler flow to both. It should select a suitable flow temp for heating and this will generally be a lot lower than to recharge the DHW cylinder. For the cylinder you’d probably hit it with about 20 degrees over your desired set temperature.

    Regarding the NTC, it depends. If the boiler/VR65 has some suitable intelligence, it could use the data to make better decisions. Viessmann certainly would. I don’t know how smart the Vaillant solution is.

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