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Different CH and HW set points

Hi, I Have a tado an Vaillant ecotech+ 424 installed for 4 years in an open vented radiator system with a HW cylinder on separate solenoid valve controlled circuits.

I'd like to be able to set a max flow temp of 50 deg C for central heating (to make the boiler condense) yet 60 deg C to steriise my hot water, always running at separate times.

Boiler has separate HW and CH max set points but if I input the above on the boiler panel it just runs to the CH max flow temp always at 50 deg C and no higher for hot water.

Can I configure tado to do what I want ?

Vaillant don't help.



Best Answer

  • GaryMGaryM
    Answer ✓


    Thanks for the info and the video link. Not good from Tado as almost every quote I have had for a new boiler is a Vaillant and going with the 424. I have the Tado room thermostats and some TRVs . I think i will pass on the Tado extension kit. Good luck and hope you get it sorted.


  • Thanks for the reply @GrilledCheese . A flow temp of 50 deg C is the minimum temp which heats my house properly in winter, I've trialled it, it works and the lower the consequent return temp the more condensing will occur according to the published boiler efficiency curves.

    Vaillant tell me its not there problem as all set points come from Tado so I'd like the configure Tado to run up to a max of 50 C when supplying rads only but go up to 60 C when I'm heating up my HW cylinder to be sure I sterilise the water i.e to optimise my system.

    Stumped how to do it so far, boiler only acts up to its max CH supply temp but ignores its max HW supply temp if set higher. Vaillant say its because Tado doesn't use the HW supply temp max , just the CH max supply temp.


  • Don’t think it’s a thermostat setting, more a boiler setting. You need it set the boiler to 60+ or the cylinder will never reach temperature and then boiler won’t turn off. Then put a blending valve on the central heating flow is the best way I see to achieve what you’re looking for.
  • Thanks to all who replied.

    My Vaillant has separate CH and HW max flow set points on its front panel and I know how to change them, it just ignores the HW set point if connected to a 3rd party controller as Vaillant describe it when I phoned them.

    Tado could make a big difference to the efficiency of how we use our boilers and reduce CO2 emissions for the same heat output if they were to kindly solve this problem as the data from the boiler efficiency graph below shows.

    Vaillant clearly are not interested.

    Could all be done with separate set points from Tado I suspect


  • Steve,

    What are the settings you use now for the Vaillant ecotech+ 424? I think i am about to have the same issues.

    Thanks in advance

  • Hi Gary, Tado still refusing to help so I run my 424 max limited at 58 deg C to be sure I sterilise cylinder hot water but know I could run much much lower for rads at say 45 C and save gas, money and pollution. The boiler has separate max settings for HW and rads but only takes notice of one of them when configured with Tado.

    Heat geek tells me they might have wired it to dumb contacts instead of e-bus (I'm the cheesed off Tado customer he refers to) so make sure its wired to e bus. I'm not convinced its incorrectly wired as it modulates and Tado sends it one two or three flame signals depending on duty required and modulates accordingly but maxes out too high for rads.

    Good luck and ask maybe ask heat geek. https://www.youtube.com/watch?v=IRybadWKsYk&t=11s

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