Opinions on smart radiator thermostatic valves?

RedMonty

So the timer on my boiler (Valliant Ecotec plus 831) has given out. Winter's here and while pricing up a new timer, of course I'm interested in what's new in home heating.

Quickly concluded the lovely-looking Nest thermostat would be a colossal waste of money for me. I have a 3 bedroom semi and small kids at school, and I don't want to be paying to heat up the whole house every day via a single thermostat in the hall. Also my habits are highly irregular (!) - I often work from home but never sure when.

We as a family tend to have very fixed times when we use each room, and rarely use other rooms at these times. This has been pretty constant for the last few years. This leads me to thinking of having individual room radiator-mounted smart thermostats - would set them to:

a) only heat up the kids rooms at bedtimes and in the morning,
b) the adult bedroom a fair bit cooler, only heating at adult bedtimes / really cold mornings.
c) heat the kitchen in time for our breakfast, and only for breakfast / dinner / only when I'm working from home / weekends
d) living room for a short time each evening (& all day weekend)

I think all this can be accomplished with 4 maybe 5 smart radiator thermostatic valves. The other radiators can be left with the current manually controlled thermostats.

I would leave the boiler on all the time in the daytime (set the new timer to only turn off at night) with the smart radiator thermostatic valves turning the radiators on and off as needed.

Not really sure what to get. Some of the stuff on the market seems ugly as sin. Wife isn't keen on having digital displays in every room.

Honeywell Evohome Wifi seems to do the trick, but maybe there are other cheaper / better options?

Suggestions?

Thanks RedMonty

Grenage

How well insulated is your house?

I ask, because in my last place, if I left the thermostat on at 18C 24/7, it cost about the same as having it come on in the morning and evening. Sometimes, keeping it simple is a money saver.

lstar337

My opinion is that the savings you may make will not cover the cost of these things.

If you want a cool toy though, go ahead.

TheCyclingProgrammer

I don't want to be paying to heat up the whole house every day via a single thermostat in the hall

Why? I think you're underestimating the effectiveness of a good smart thermostat in a typical 3/4 bed house. We have a 4 bed semi and a Nest in the hallway, away from any drafts and it works almost perfectly:

* We have TRVs on all the radiators in the house except the two in the hallway and the towel rails in the bathrooms. Most of the upstairs TRVs are set to max, some (master bedroom and living room) are down a few notches.

* Our Nest thermostat is set to our preferred temperature (20-21C usually) from 7am until 11pm and set to 17C overnight. Its motion sensor (and the one in our Nest protect) and the GPS functionality on our phones work to auto-disable heating entirely when we are out of the house, although there's a fallback temperature of 12C IIRC for frost protection.

* Our house is reasonably insulated although some parts of our loft only 100mm. We have double glazing though its about 12 years old so not as efficient as modern glass. We have composite front and back doors with minimal glazing and a conservatory open to our kitchen with thermal film on the roof. All in all about average - could be better, could be worse.

Overall, after experimenting with TRV settings in certain rooms, the house maintains a reasonably consistent temperature throughout - when its reached the ideal temperature in the hallway the rest of the house is within 1C of that temperature.

Our heating started coming on again about a month ago when it started getting colder and in that time its not come on for more than an hour a day on average, mostly in the morning and briefly in the evening as the outside temperature drops. We occasionally put it up half a degree if we don't feel warm enough.

As I have the whole thing hooked up to a home automation server I can see a full history of the Nest's temperature readings, humidity and also outside temperature. To give you an example, the outside temperature reached a low of around 5C last night - pretty cold - and was below 10C from 8pm until about 10am this morning. The heating had come on briefly (about 15 minutes) around 10:30pm so the hallway temperature was at its set point, 20.5C at 11pm. It only dropped 1C over night so by 7am the heating only had to come on a very short time to get it back up to temperature.

Based on last years readings, once we get into the coldest point of winter, we may find the heating is on anywhere from 2 to 5 hours a day but this kind of usage only lasts a couple of months each year. I have no complaints about our energy usage overall.

We don't take full advantage of all of the Nest smart scheduling features - because the house is almost always occupied (I work from home) a simple manual schedule works for us. If your schedule is a bit more complicated you might have more luck with the Nest's learning and automated scheduling.

getmore4less

will all the doors on the rooms not being heated at special times be closed at all times?

zoning only really works if you isolate the zones

One way to heat the bedrooms is open the doors and use the heat from the lower rooms around bedtime.

unless rooms are thermally isolated you get conduction anyway.

The other issue is the thermal inertia of the property and the heating system, we went with a single programmable stat.

we have overnight at 15c and on really cold overnights it gets below 17c a good 30min warm up time.

when away in the winter and the fabric of the building gets down to 10c needs a good 12-24hr to stabilise to comfortable.

What you could do is pick a system that supports programmable rad stats but start with a house stat for each of your current zones(maybe just one) and see how you go,

RedMonty

Grenage wrote: »

How well insulated is your house?

I ask, because in my last place, if I left the thermostat on at 18C 24/7, it cost about the same as having it come on in the morning and evening. Sometimes, keeping it simple is a money saver.

That's an interesting thought - how did you work out the weekly cost of the different strategies?

I'm guessing you recorded the gas meter reading at the start and end of the 7-day period, and hoped that the average weather wasn't too different from the previous week.

RedMonty

TheCyclingProgrammer wrote: »

Why? I think you're underestimating the effectiveness of a good smart thermostat in a typical 3/4 bed house. We have a 4 bed semi and a Nest in the hallway, away from any drafts and it works almost perfectly:

* We have TRVs on all the radiators in the house except the two in the hallway and the towel rails in the bathrooms. Most of the upstairs TRVs are set to max, some (master bedroom and living room) are down a few notches.

* Our Nest thermostat is set to our preferred temperature (20-21C usually) from 7am until 11pm and set to 17C overnight. Its motion sensor (and the one in our Nest protect) and the GPS functionality on our phones work to auto-disable heating entirely when we are out of the house, although there's a fallback temperature of 12C IIRC for frost protection.

* Our house is reasonably insulated although some parts of our loft only 100mm. We have double glazing though its about 12 years old so not as efficient as modern glass. We have composite front and back doors with minimal glazing and a conservatory open to our kitchen with thermal film on the roof. All in all about average - could be better, could be worse.

Thanks for your information.

To be honest, our house is good in some aspects, not up to scratch in others.

It's a 1930s metroland semi in NW London, which means it's pretty drafty, with reasonably high celings. All windows now double glazed.

Loft is floored with chipboard (and full of junk), and has so-so loft insulation (100mm glassfibre on top of piles of old newspapers from the 1950s(!) ) plus extra insulation under the roof tiles, held up by rather flappy membrane nailed to the roof rafters. ('Warm loft" style.) Both were done in 2010 by builders who we later had problems with. I'm skeptical of how well insulated the loft is, given that it's still a bit drafty up there (possible gaps in insulation, drafts from eaves into the loft space etc. I'm aware the underside of roof tiles need ventilation, but it seems to be coming though into the loft) Redoing it would mean clearing the loft, taking down the membrane and checking, plus taking up the loft flooring and replacing / topping up insulation where needed.

Ground floor is suspended (with a cavity underneath) stripped wood from the 1930s. Two seperate handymen at different times messed up filling in the cracks between the floorboards, so that is still as drafty as an elephant's shithouse door. I'm sourcing quotes for someone to go down into the cavity and put up kingspan/rockwool between the joists. My mate is willing to do it for a few quid, but the wife wants a professional to do it, so that is extra cost.

Previous owner put in french doors in the 1990s, that open to our kitchen / dining room (where we spend most of our time). They're double glazed, but the doors and side panels have a large white alu frame that feels freezing to the touch. The glass itself always feels colder to the touch than the window next to it that we had replaced in 2010. Seriously considering buying a large roll of thick transparent window film, cutting to size, and sticking that down on the panes & frames to reduce heat transfer.

So all in all, a decent list of jobs. But the comment from above about it being the same costs to heat the entire house as separate rooms has made me think again. Just need some confidence in methodology for comparing weeks with different weather.

TheCyclingProgrammer

I would certainly focus on things like insulation, where possible, and having a good programmable thermostat. I'm not convinced zoned heating is worth the outlay unless you have a big enough house with logical zones you want to heat separately.

For a typical 1930s semi, like ours (4 bedroom extended) it makes more sense treat the house as a single zone to keep the house at a constant average temperature, only turning TRVs down in some rooms for comfort (for instance we prefer our bedroom to be slightly cooler).