I had a new system boiler, hot water tank and Nest installed about 9 months ago. We have the hot water come on from 7am until 8am and then from 5:30pm until 6:30pm and that's it.
The morning schedule covers us for the day - any washing up, cleaning, shower after gym etc.... The second schedule covers us for baths and showers in the evening (kids have a bath at about 6pm so the schedule ensures there is hot water for them and it tops it up afterwards for ours later).
I have very occasionally used the boost function to add an extra 30 minutes if we've been decorating and used loads of hot water to wash up or been for a muddy walk and needed to wash earlier.
The heating is on 24/7 but cycles through different temperatures at different times. It has to hit 21 for 8am when we all get up, drops to about 19 for the rest of the day and then jumps up to 21/22 for the early afternoon. Going down to 17 for the evening and overnight to ensure it doesn't get too cold. What actually tends to happen is the house hits 21 at 8am and then stays warm throughout the day and into the evening and drops down to about 18 before heating up again for the next days cycle (to hit 21 for 8am).
The Nest system as a whole works flawlessly and we occasionally use the app to boost the house up to 22 or higher if we've been on a really cold walk and want it to be warm for when we get in. The only thing to remember is that if you schedule it to be 21 at 8am it may start heating the house at 6am to get to that temperature (we originally set it to about 20 at 6:30am and I noticed it was coming on full blast at like 4:30am to get it there, meaning I would wake up at that time boiling).
Family of 4, large detached house.
I have an unvented indirect HW cylinder that the central heating coil runs through and warms the water. Wouldn't it make sense therefore that every time the central heating is on it does this rather than scheduling separate times for the boiler to fire up to warm the water? I get that this is required when the central heating isn't on (summer) but isn't there a setting that does this? i.e - always heat water if the central heating is on?
I suspect this would make your heating very inefficient. When ours comes on I want it to heat the radiators as fast as possible to get up to temperature. I don't imagine there is a massive amount of water in the heating system, pipes and rads but our hot water tank is about 160L. If it had to do the heating and make sure 160L of water was up to temperature it would just slow the whole thing down.
With our Nest the hot water tank has a temperature cut off (about 60 from memory) so even though the hot water is on for an hour in the morning and evening, it may only actually heat for half that time if needed.
