Forum menu
I bought a Nest for my work unit many years ago when it was pretty much the only "smart" (as in connected) option, primarily because the existing thermostat/control unit was absolutely horrendous to program/schedule whereas the Nest is a doddle and can easily be adjusted remotely if e.g. no-one will be in because it's a bank holiday. Never used any of the auto-adjusting features/away mode etc. It doesn't have zoned heating but then we don't need it. Has worked flawlessly for years but would not recommend it unless your needs are [I]very[/I] basic i.e. just want to be able to schedule easily from an app and check/adjust temp remotely. Assume Hive is broadly similar.We recently got a Nest thermostat when we had a new boiler installed. I wasn’t convinced, but my Wife seemed keen to have some ‘smart’ functionality, although I am fairly convinced that she had no idea what that actually meant for a heating thermostat/controller.Anyway. It’s pretty meh.
interestingly (or not 😃) it was only when I fitted my smart TRVs that I discovered most of the regular ones were stuck and didn't actually do anything 🤣The cheapest solution at the minute would be to turn off your manual TRV’s in the rooms you are not using
Our Hive is only used as a timed/programed zone control. The thermostat side of each Hive TRV is a bit flakey/needs calibrating a lot, so i just use it to completely turn on/off certain radiators.
Mostly upstairs (with one downstairs in the hall), just to open in the morning when the heating is on to warm up before work, off during the day when we are downstairs then back on at night before bed. The only exception is the office, where a: the desk is right next to the rad and b: when i open the TRV the rad heats up so quick it doesn't need advance warning! The Hive TRV comes on in the spare room for an hour during the night just to keep any damp at bay.
Could do with a couple for downstairs as well, just to lock out the rads in the living/dinning room when the log burner is on (cant reach normal TRV as behind furniture). The main Hive stat is in the kitchen, with a normal TRV fully open on that rad. as mentioned above, if you have a TRV and thermostatic controller in the same room they can end up fighting each other in certain circumstances. You should also have at least one rad in the system with no TRV on at all (often the bathroom) this should be enough to reduce the return heat temp to the boiler if all other rads were closed. our boiler just wont fire if the return temp is too high, the pump keeps circulating the water until the temp drops enough.
None of the above is 'smart' though, all set up through the app. It doesn't learn our habits, Geofencing is only an alert not an action within the app. It really cant cope with a flexible shift pattern for example. I work mon - fri same hours each week, Mrs F can work any 3 out of 7. There isn't an effective way of managing this through Hive that i have found.
Just on the balancing thing...
When all the TRVs are shut, the flow will go to the last remaining path of least resistance. This is easy to design in with either a bypass or a permanently on radiator.
When all the TRVs are open, you expect to get an proportionate flow through all the rads. This is hard to achieve and is why you need balancing.
The pressure drop across a pumped system with an incompressible fluid (water) is determined by the flow rate and resistance to flow. It is just like calculating resistance in an electrical parallel circuit.
1/R = 1/R1 + 1/R2 + 1/R3 ...
or 1 = R/R1 + R/R2 + R/R3 ....
You can think of this latter form as the proportion of the total flow going through each radiator. If R1 has a resistance close to zero (path of least resistance), then the total resistance R will be close to zero and R/R1 will be close to 1. Almost all the flow will go through that one radiator.
Lot's of approximations in this. The theory gets as far as saying it is easier to balance circuits where all radiators have some form of restriction rather than trying to balance things with everything wide open.
That restriction also reduces overall flow rate lowering the return flow temperature. This is good for boiler efficiency (condensing).
Genius home / Genius hub will do what you want.
It has a footprint mode which tracks the rooms you populate, when and builds a heating profile around it.
Seems pretty smart from the reviews I've read but I imagine the payback is hefty.
I plan on getting it for the house but want proper integration through the API so I can do other things with the room sensors.
Honeywell Evohome allows each room to be its own controlled zone - the main unit has a thermostat that can be used but doesn't have to be. It worked brilliantly for me when I was on oil as it kept the cost down.
For the OP it's overkill - if you're moving around the house in the days there's no massive benefit to be had, except that your wife and yourself can set the rooms to your own preference.
Re her approach of turning the thermostat and opening the window - my ex used to take that approach. Get Greta around to have a word !
The evohome system has an "open window" detection facility where if it detects that it's trying to heat the room but the temp isnt changing it determines that a window has been left open and turns off the heating in that room.
You can also program in an offset to the temperatures - intended for calibration but could be used for whatever purpose you decide.
When all the TRVs are shut, the flow will go to the last remaining path of least resistance. This is easy to design in with either a bypass or a permanently on radiator.
If it's all fully smart TRV's the boiler and pump won't fire up as they rely on a TRV calling for heat via the hub/controller. From what I can see of our newly installed boiler a bypass is now a feature on heating circuits. The plumber installed one as it wasn't present.
The evohome system has an “open window” detection facility where if it detects that it’s trying to heat the room but the temp isnt changing it determines that a window has been left open and turns off the heating in that room.
I've had the evohome system here for a couple of years and I've been tempted so so many times to switch that on, but thankfully the kids have learned to shut windows/doors without me doing so!
Similar to @FunkyDunc, we installed Honeywell evohome not long after moving in so I don't know if it's saved us money compared to a non-smart system. However, compared to our previous house we’re using a lot less gas which surprised me, as ours should be a much less efficient and much more expensive house to heat.
Previous: 262sqm 6-bed detached, 2006-built, modern insulation etc.
29,271kWh gas over 12 months
Current: 178sqm 4-bed detached, 1870s-built, minimal insulation, high ceilings etc.
21,568kWh over 12 months, including significant WFH during lockdown
That’s with 9 individual zones, including a conservatory. Hate to think what our gas usage might be without a smart system.
sounds good but damn - the price 💰💰💰😃Genius home / Genius hub will do what you want.
It has a footprint mode which tracks the rooms you populate, when and builds a heating profile around it.
Would be interesting to see a proper technical analysis/review of it but couldn’t find one. Room occupation dynamic scheduling is cool - I’ve manually scheduled our heating based on what I [i]think[/i] our routine is but it would be interesting to see actual data (although IME PIR motion detectors - which it looks like these are - aren’t an ideal solution for that).
API is open though - looks like the Home Assistant integration can access the data, including room occupation. Be very interesting to know how reliable that part is, if you end up investing!
Controls now commissioned by the sparks today. I'm waiting for the TRV's to calibrate before throwing the heat on demand switch and allowing them to control the boiler. Should be live early next week once all the firmware updates are in place too.
I stand corrected on the radiator balancing issue. I knew that you balanced with the lock shield valve but thought that if you then turned the TRV valves on half the radiators to low, throttled their flow, it would affect the flow to the others.
They should all be in parallel and the balancing is to account for the different pipe lengths to each rad. Once balanced the flow should evenly divide between all radiators and turning one of more off will make no difference.
If you turn too many off the pump might over pump, but IIRC most modern CH pumps can sense flow and back off as radiator TRVs switch off (ours certainly does).
No experience of it so can't recommend personally, obviously there's a few on here very pleased with it tho: Tado starter kit & 3-valve packs almost half price on Amazon at the moment.
https://www.amazon.co.uk/dp/B098BKHT3R?smid=A3P5ROKL5A1OLE&tag=pepperugc03-21&ascsubtag=2257400699
https://www.amazon.co.uk/tado°-Radiator-Thermostat-Universal-Mounting/dp/B098B2XP8C/ref=pd_bxgy_img_1/260-6611601-1495959?pd_rd_w=4KAh6&pf_rd_p=c7ea61ca-7168-47e3-9c8b-d84748f5b23c&pf_rd_r=YG2TNEDCYDAV0H9NKEVG&pd_rd_r=6fab7bb2-edba-4805-bde8-7fc1034c51bc&pd_rd_wg=YAUhS&pd_rd_i=B098B2XP8C&psc=1
PSA
Tado starter kit currently half price in Screwfix
https://www.screwfix.com/p/tado-v3-heating-hot-water-wireless-smart-thermostat-starter-kit/141kt