I have reached the same conclusion - it was fitted 15 years ago, initially the house had only a simple timer and some TRV’s, but it seems to do some “clever” things we are not aware of.
As we get closer to steady state this evening you can even see the pulse width start to change as it ties to to prevent an overshoot.
The question comes is the constant cycling, including pumping round the bypass, to maintain the temperature setpoint using more gas? I need to get the smart meter data from Octopus, lust learned they have an API, to find out. Since being forced to go “smart” I have no way of measuring gas now, there is no pulse or anything on the meter!
I am looking for a better control system - is Home Assistant any good? I want to be able to control TRV valves as well, at the moment these have simple timed programmers.
You can see it In my Airing Cupboard Box working below!
There are 4 mains neons connected through black tubes to photo diodes and a small comparitor circuit to drive 4 digital inputs on a Pi ZeroW these pick up the mains signals to
- Hot Water Demand (from timer)
- Hot Water Heating Demand (from Thermostat on tank)
- Heating Zone Valve Open (i.e. programmer calling for heat)
- Pump Supply
You can also see
- 1 Wire connection (the three terminal strip above comparitor board)
- USB OTG Hub (to right of PI) this provides serial & power connections to the Arduino measuring the solar divert power and a 2nd Arduino measuring the boiler current.
At the moment it only monitors my system The space in the bottom right is for a couple relays to allow control at a later date. The multi core cables go to the box where all the terminals are connected.
The PI ZeroW makes API calls to the emonPI on the “control” V-LAN to log the data.
It’s all a bit home brew, at the time I needed the logger for the solar divert the emon shop was bare so I improvised to make one, the rest of it sort of grew organically!