Hive, Nest etc, cost-benefit calculations

[oldbutnotdead]

Idle curiosity really- has anyone ever done the sums to see how long the things take to repay their cost by reducing the heating bills/making the home more comfortable
I can see the theoretical attraction but not sure about the actual. For instance, most of the year I'm at home on a normal day/night schedule. For a few weeks I work night shifts. So for those weeks I switch my cheapo wireless Sunvic programmers from P8 to P9- takes about 10 seconds.
When I was working fulltime the evening heating schedule ran til 11pm anyway, if I stopped at the pub for a few after work the place was still warm at 2am so no need to boost the heating via an app (which didn't exist at the time). Likewise mornings, heating on at 7am til 10am, place still warm at 12 noon if I fancied a very lazy start to the day (Edwardian terrace, no wall insulation, DG, lots of loft insulation, gas bills low enough that Transco used to come and check I wasn't running a bypass every couple of years)
Share your stories.....

 

[muggles]

Every home will be different, so it's impossible to do a single calculation which will demonstrate a blanket saving. There are just far too many variables. If you do have super low bills then obviously the benefit is going to be much less. I spend less than £300 a year on heating oil, for example, so buying one would take years to pay for itself if it ever did, but someone spending £3000 a year might see a faster payback. I've got a Honeywell T6R-HW, because Honeywell gave it to me as a test unit in the final prototype phase before they released it. I don't really interact with it much

 

[bernardgreen]

Share your stories.....

Too cold....... Add more coal to fire,

Too hot....... Open a window.

No coal in shed and still cold....... put more clothes on

Too hot and windows already open.........

1950's

 

[aptsys]

Depends how it was set before. There's nothing about these devices that makes anything more efficient other than turning off the heating when you go out.

 

[cdbe]

Surely you will save 30% on your heating bills - Advertising Standards Authority anybody?

 

[75pete]

Expect it also depends on what you had before you have nest or hive fitted and what you need in the why of improvement to your heating and hot water control.
Ours, old programmer and old room stat, both 30+ yrs
Improvements needed, better control of the hot water
Better schedule of both heating and hot water
Internet control
Price does play its part but both nest and hive are quite simple DIY installations for most systems.

 

[muggles]

Surely you will save 30% on your heating bills - Advertising Standards Authority anybody?

Up to 30% on a multi zone solution like EvoHome I believe is the official line

 

[ianmcd]

both nest and hive are quite simple DIY installations for most systems.

you wouldnt think so reading this forum

 

[75pete]

Haha, this is very true Ianmcd. I asked about fitting Hive and was very pleased to get great feedback from the lads on here willing to give freely of their time and experience.

 

[ericmark]

I would not think it saves anything, assuming the TRV's are set correctly then they keep every room at correct temperature as set for that time of day, all the wall thermostat does is stop the boiler cycling.

Hive is rather useless anyway, it is not OpenTherm and does not connect to the TRV's, Nest is OpenTherm and can connect to Energenie TRV heads, so Nest may be better than a simple off/on thermostat.

But as to anti hysteresis software with a non modulating thermostat can't see how that helps with gas, oil is different as even if boiler does modulate it does not modulate much, but with a gas modulating boiler switching it off/on is likely to waste more fuel than allowing it to modulate.

However I have only 4 electronic TRV heads fitted, they are not on all the radiators, and the idea was to turn down the heating on ground floor at night, and dormitory area in the day, however the house is well insulated, so the setting may be 16°C at night, and 20°C in the day, but in real terms at night it rarely cools to 18°C the house simply does not lose the heat that fast.

On the heating side when the house has cooled due to being turned off completely other than frost protection, it will heat from 16°C to 18°C within the hour, but 18°C to 20°C more like 3 hours, if I actually cheat and set temperature to 24°C then it will raise from 16°C to 20°C within the hour, the boiler and radiators have the power, it is the software trying to stop over shooting which delays the warm up.

It does not matter how smart the wall thermostat is, unless the TRV allows the radiator to heat up, it will do nothing. So a Terrier i30 ebay price £12.50 so 10 only £125 still cheaper than Hive or Nest, each room set according to standard use, a simple thermostat in one or two rooms may be to stop boiler cycling as weather improves.

During the Summer I try to keep house cool, the last thing I want is on a clear night for the central heating to cut in, then have the house too warm in the day, only way I have found to ensure this is to manually turn it off. So from March to November manual control as an when required, and November to March the TRV's control each room, next step would be EvoHome or Tado when the TRV head tells a central computer if heat is required, then the central computer tells the boiler what output is required, as long as the boiler is opentherm.

To my mind with gas either just swap the wax heads for electronic and stay with simple thermostat, or go all the way, no point going half way with Hive or Nest, yes Nest will link with TRV head, but thermostat and head then set to same temperature, and whole idea is each room set at different temperatures.