how to set up valve fully open?

edited December 2022 in General Questions & Topics
is there a setting option to set up valve openning style? currently I noticed it can open in 3 levels 1 2 3 bars. although it seems sensible to do in this way to make temperature changes smoothly. However the result for small and big rooms are quite different. you should make judgement on the room size by measuring the speed of temp increasing. then decide what is the amount of over shreshold temperature it should heat to. or it doesn't make sense to open valve in levels.

the worse thing is when the valve is in 1 bar level. the boiler won't reduce the gas consumption and water pump output. the cost at the boilder end in fact has been increased 3 times if it can reach the target temperature. correct me if I am wrong. this is not acceptable. I need a setting option I can choose how the valve open. fully or 3 level way. other wise I will pay much more gas bill because of this design.


  • Hunter
    edited December 2022

    As the Srv closes Ignoring losses if less heat is taken from the water circulation then the boiler will modulate down as the return temperature will rise and the boiler will turndown the gas to maintain a controlled discharge temp. This is not load compensation but normal boiler modulation.

    if you start manually opening the valves then you will lose that part of the control logic which seems a big part of the control philosophy.

  • You haven’t said what devices you’re using but if they’re connected to the boiler on a relay the Tado device can’t reduce the heat output on the boiler, it can only cycle it on and off. Not sure how a fully open valve would help you but Tado should fully open them when there’s a high heat demand.
  • Hunter
    edited December 2022

    The boiler will only cycle if the heat demand is below the min turndown of the boiler. Cycling is also not the end of the world, yes increased losses but flame off, pump continues to run until either temp or time trigger and then reignites if demand remains. At least that’s how mine works, so indirectly the boiler duty can be reduced by a Tado valve within limits.

  • my system is 1 wireless receiver directly connected to Worcester Bosh Combi Green star boiler. then 6 trvs.
    The thing I'm not sure is when only 1bar/3 highlighted if the boiler is burning gas? I know the boiler pump is surely working as I can hear water flowing in the radiator. if the boiler is burning and the valve only open 1/3, it's surely a way of waste energy/money
  • there should be a indicator showing if the wireless receiver turned The boiler on/off.
  • I thinks it’s worth you looking at the boiler during these periods. For relay you will find it’s on periodically on a set frequency, say 4mins every 20mins or if it’s Just entered wave 1 it may not be doing anything just waiting for the temp to fall. Basically you can’t tell without looking at the boiler. Also to add further confusion if you hear water it doesn’t mean you are burning gas, it may be cycling with flame off as part of its normal operation. If you are burning gas it may also be a low amount depending on the demand.

    If the radiator is getting warm on wave 1 then it’s not a waste. If the boilers on and the rad is not getting warm then it’s not meeting its objective and the looses will out weigh any benefit.

    I think it’s a mindset thing.

  • If it’s a relay connection Tado will only be able to turn the boiler on and off so it will be down to the boiler to choose whether it should ignite or just pump water around. There should be an indicator on your boiler to show whether it’s ignited, Tado will have no way of knowing.

    Tado modulates output using trvs to try not to overshoot target temperature. If you use a simple on/off thermostat and/or dumb trv you’ll find there’s much more of an overshoot.
  • thanks for all The comments. do you know how tado wireless receiver control the boiler on/off? tado surely knows if the boiler has been triggered on or off. its not so convenient to observe the boiler's status as it's in the loft. but if try the temp raise from 18 to 18.5 you would notice 1 bar shows, the vavle moved swiftly. if you set it 18 to 22C you will see 3 wavely lines and longer valve turning sound.
    that says sth I believe.
  • Those waves translate to a duration and frequency of the relay closed and thus boiler activations. Also if your system has SRVs they will also open more during a higher wave pattern. The waves modes are determined by the algorithm. This seems to look at both distance from setpoint and also rate of change of temperature. The boiler firing and Srv position work to get heat to get heat into the room to either meet setpoint or arrest drastic falls in temps. I thinks it’s a more involved TPI controller.

  • I think this is a very stupid system. I am pretty sure when app shows 1 wavely line the vavle is only partially opened. rad is warm not hot. it takes longer time to heat up to set temp when the boiler is burning. I tested this in a small room.
    so I need an option in setting to select either fully open or tado open.
  • I think you’d be better off with a simple on/off thermostat, it sounds like that’s what you want Tado to do.
  • It’s wave 1 because it’s close to setpoint and thus it needs control the heat input to prevent overshoot. Sounds logical to me. Try hive it’s a straight out of the box system with no clever on off business. The SRVs are troublesome however.

  • 6 valves plus wireless receiver package. it's a big investment. not easily to change to hive now.

    I can see the point to reduce vavle opening to avoid overshot. But it's just like covering your eyes to say the lights are turned off while the bulb is still shining brightly. they reduce the vavle opening but the boiler is still working in full power. is it ridiculous?

    If they cannot auto fully open The vavle they should give user such control options!😡😡😡
  • The bulb will dim due to boiler I mean bulb modulation.

  • Hello!
    So the answer is no? I don't need Tado modulation either. My Tado thermostat is in on/off setting and is commanding the circulation pump of a air-water heating pump. The problem is that there are radiators without thermostats in the house and every time a Tado radiator thermostat opens to 1, the hot water circulates full speed at these thermostateless radiators. So, if the temperature difference is small I have a warm radiator and 4 others who are hot and the heating pump in maximum load. I do not need the 1-2-3 degrees, I just need the fully opened or fully closed valve. Is it possible?
  • johnnyp78
    johnnyp78 ✭✭✭
    Can you balance your radiators - do they have lock shields?
  • @tanghzuk, you do realise that a dumb TRV also works in exactly the same way. As the temp gets closer to what the valve is set for, the valve starts to close. It isn't a simple open or closed

    It's also worth pointing out that 1 or 2 bars bar doesn't always mean the heating will be running. It may take another room to call for heat before Tado starts the boiler. I see this with my system e.g. room set to 19 and temp is 19.5 but dropping. Valve will go to 1 bar but heating won't start running. Another room then calls for heat and the system starts. This behaviour reduces cycles on the system

    I also note that if the temp in a room is rising, Tado will shut off below set temp to allow the remaining heat in the rad to bring the room up to set point. This can also happen if the room is getting solar gain so this reduces consumption and boiler cycling.

    Note that my system is on a relay and not using opentherm

    I think you need to let your installation settle down and see how it behaves. Your analogy of the lightbulb is flawed as a boiler doesn't run at full power all the time. Even in a relay based system, the boiler will heat the system then shut off when the circulating water is up to temp (e.g. 70c) . It'll only fire again when the water temp drops by a set amount (e.g. 10c) below the set temp.