I implemented TADO for controlling heating in our house, before starting the rest of the home automation. This lead me to chose a well know system with good recommendation.
However, the limitations of TADO system have become a big challenge for me, with no flexibility for users.
My simple question is. Is there a way to set the opening of a TADO TRV in percentage or any other definite opening?
Avoid setting a temperature, as the TADO then calculate the opening, which is not working for my heating system. I end up with huge fluctuations in temperature due to old pipes and radiators. Further TADO TRV’s open too much, leading to less than expected cooling of the water, resulting in penalties from the heating provider.
I believe I can do a better mathematical opening percentage than TADO does, if just I can set the percentage.
To be honest I don’t, I am not sure by design that many if any will control opening other than full open or full closed. I am no expert but partial opening is not desirable in most cases as this will affect the radiator balancing that should be done via the check valve and not the thermo valve.
Problem in DK is that most people do not have the “check valve”, hence the radiator thermostat should solve it. Old manual thermostats actually do this, at least the versions used in DK.
TADO TRV is capable of controlling the opening percentage, they just go for very high or very low numbers, leading to big fluctuations in temperature of the radiator.
This should not be done by the thermostat but should be properly set in the valve. If the valve does not have such a setting, it is often done through a valve in the foot of the radiator.
There’s a process called “Hydronic balancing” (I hope it is translated accurately, “waterzijdig inregelen” in Dutch) which is intended to set the level of flow for each radiator in such a way that the temperature of the water is cooled just the right amount when returning to the heating system. This can be done by professionals using proper measuring equipment, but you can also do it fairly well manually yourself using guides online. But you do need a way to control the flow, and it may lead to extra noise.
Edwin, i agree this would be a good way of doing it, however will be costly in a old house. They will need to cut the pipes to implement, hence not in anyway feasible.
If your valve lacks the means to set it you may be out of luck. But depending on your valve it may also be possible to replace an insert valves behind the TRV with one that has the required setting. It would require one time emptying the pipes (or freezing it locally) and replacing an insert of the valve. No cutting or soldering. If your valve looks something like the picture below the required setting is already there, or you may be able to only replace the insert (the copper bit in the picture) with an adjustable one like the one in the picture:
If they are thermo-electric valves, just PWM the valve. You can probably measure how many tenths of millimeters the valve pin moves for each 10 second open and how quickly it closes when unpowered. That will give you a decent PWM frequency to start with.
Then to get 50% open, just run the value on 50% duty cycle.
If it’s a basical thermo-electric actuator valve, then it’s literally just a resistor heating a puck of wax. It will be fine with PWM, even without 0 cuts.
However, if you are hoping to keep over and undershoots below 1C or even 1.5C, depending on circumstances, you will seriously struggle. Even if you shut the radiator off instantly with a mechanical valve the radiator thermal mass will continue emitting heat for while afterwards and vice versa on power up.
You could get better results adding buffers to you targets.
