Many years ago, my daughter has a new house, and I in error advised she turned the thermostat for the DHW down to save money, what did happen was the immersion heated the water instead. Giving her a high electric bill.
Not an easy thing to work out, for years after that, I thought electric costs more than gas to heat DHW, likely it does when the central heating is running, but not when central heating is not running due to cost of heating a cold boiler, but amount of DHW used, and the pipe runs can also affect which is cheaper.
I do believe Tado is good, and now in summer is the time to change it. Loads of time to correct mistakes. But I have lived now in 4 centrally heated houses, and each one has changed my views as to how heating and DHW needs to be controlled, first was hot air, so really down to three, and one can hardly believe how different.
Two were rather old fashion houses, with doors down-stairs, one was open-plan, and with the open plan, all the TRV's did was stop bedrooms overheating, but with the homes with doors, there was a problem getting the boiler to run as and when required, and the problem still exists with this house.
The problem is the height of the thermostatic control, we see pictures
but, most of the books were written before we had better quality double glazing, linked TRV heads, and condensing boilers which must, to work, modulate (able to turn down output) so many of the old ideas no longer work.
The main problem is, it is natural to answer questions based on one's own house. My experience setting lock shield valves, taught me there is no one method, in the two houses with doors, the settings are completely different. Likely as one uses micro bore and is oil fired, and the other 15 mm pipe work, and gas fired, but it means what works for me, may not work for you, so explaining why is important, not just a do this, because this is the way we have always done it.
The Worcester Bosch Greenstar installed in my mother's house, had no option for any ebus controls, but it seems latter versions did, however they had to use Worcester Bosch own wall thermostat, and did not connect to TRV heads, so were limited as to where they could be used. The installers were a load of cowboys, as they connected a power shower to a combi-boiler, and fitted an external by-pass valve when one already fitted in the boiler, they also removed all the hard-wiring to the wall thermostat, and fitted a non-programmable type, although to be fair, good quality.
Both mother's house and this house, what did become apparent was one wall thermostat did not work, wind direction, sun through windows, etc, mean the same room is not always the coldest, so in both cases we ended up with multi-wall thermostats in parallel. But the open-plan house worked fine with a single wall thermostat.
The idea of linked TRV heads, sounds good, but again in practice there are problems, when heating is running they work A1, but since radiators against the outside wall, tend to fire up the boiler when not really required.
I was lucky, as when wiring up the central heating, I had no thoughts about solar panels, but since all from the same FCU (fused connection unit) it was easy to all battery back up to the boiler. Also as a result of solar panels, my electric costs vary through the day, get paid 15p/kWh for export, so using solar power means not paid for it, so calculate at it costing 15p/kWh, off-peak is cheaper at 8.5p/kWh, and peak at 30.17p/kWh so the best option to heat water is a time clock so heated from 00:30 to 05:30, but I use an Iboost+ so uses solar as well, I made a mistake, but what it does mean, electric heating of DHW is for me cheaper to using oil. Other people may have a different system so that oil/gas is cheaper, but one has to consider what may happen in the future.
You can't find out what it cost in p/kWh for gas and oil, as the shorter the burn time, the higher the losses, so for one family gas/oil may be cheaper, and for another family in the same house, electric could be cheaper. But in real terms, once losses are considered, likely not much in the cost, at 12 kWh per week that I use, likely less than £2 per week, hardly worth worrying about.
Because I have the iboost+ I know what the electric costs, without it, I would be guessing.
