Looking for a thermostat

[JP_]

Hi

I am looking for a fully programmable thermostat that allows temperature settings at different tines, e.g. 20C 6am-9am, 16C 9am-4pm, 20C 4pm-11pm, 16C 11pm-6am, but 20C all day at weekends.

I've seen one that does 4C below set temp at night, but nothing that allows more complex settings.

Any suggestions?

 

[Diyisfun]

Honeywell CM907. Hard wired or wireless, I have 1 of each.
Easy to set up & change time/temp holiday modes, min temp.
Good piece of kit.

 

[gblades]

I used to have a Netatmo Thermostat (before fitting a new boiler and opting for their thermostat). What I liked about it was that either the thermostat itself or the wifi/relay module could control the boiler. As I didn't have a thermostat previously I simple wired the relay module into the boiler and put the thermostat on a bookshelf. The thermostat runs off batteries and the originals were still working fine 18 months later when I removed it. It is now fitted to the gf's oil boiler.

 

[muggles]

Essentially most programmable thermostats on the market will do this. Honeywell T4 / T6 Lyric / Nest / Hive / Tado / Honeywell CM907/927 etc etc

 

[ericmark]

I also wanted a thermostat which I could program and considered wireless was the best option. I already had a wired Horstmann DRT 2 at home been running for years without problem, also daughter and son had the same which was programmed as 5 days all the same with 4 times, and two days independent with two times each. So I bought the Horstmann HRFS1 which was wireless and did either similar to DRT 2 but with 5 times, or you could select for every day independent. It seemed ideal and I fitted it to mothers house and the remote part sat on a chest of draws looked like a thermometer although you could fix to wall as free standing it was measuring air temperature not wall temperature.

However then it started to go wrong, for what ever reason it would fail to tell base unit to switch on or off and it did not seem to send repeat commands, so once missed the house would either get hotter and hotter or cooler and cooler, only then did I look at the spec for the original thermostat, the Honeywell Y6630D has no programs, it is wireless it has no fancy display and looks to be about the simplest thermostat you can buy yet costs £120 compared with £67 for the Horstmann HRFS1, however it resends information to base and if the remote is not seen in an hour the base shuts down, it fails safe, however it has never failed except for discharged battery which seem to last for years.

It also has another very important feature, it does not simply switch off at set temperature but it starts to switch off and on before the set temperature and after the set temperature using what is called a mark/space ratio which stops the hysteresis normally associated with cheaper wall thermostats. Seems there is a good reason to pay the extra it does a better job.

With standard radiators and a modern boiler it would seem the EvoHome is the bees knees, however with better quality radiators which are fan assisted this system it seems will not work? So not sure which is the best system, using fan assisted radiators means the room temperature is even there is no problem with furniture in front of radiator and the radiator itself has the temperature control built it, you can even use same radiator for cooling.

But the problem today is if you control each room independent, the Pegler Terrier i-temp i30 programmable radiator valve at £22.50 is about the cheapest allowing accurate and timed temperatures for each room, how do you control the boiler? You could simply manually turn it off in summer and on in Winter. I did not go for the super cheap, mine are connected to a hub, however because they sense both air and water temperature they auto compensate for the heat from the radiator and do keep the room to temperature set.

However in this case the anti hysteresis software is too good, if I set the room to heat from 16°C to 20°C at 6 am, by 11 am it has just about hit new temperature, so it is set to go 16°C to 24°C at 6 am and then 24°C to 20°C at 8 am and that works. I am using Energenie there are many more. With mine they will work with Nest, it uses an "If This Then That" IFTTT protocol and Nest can either follow the TRV head or the heads can follow Nest.

My idea was to get Nest at a latter date, however I have found the house is so slow to cool down, the old Honeywell Y6630D and programmer (time switch) is doing a grand job, so I have not as yet fitted Nest, however Nest also has anti hysteresis software so does seem a reasonable option and uses two way coms so no problem with loss of coms it continuing to heat or cool.

However unless using the OpenTherm connection between Nest and the boiler not sure you want a wall thermostat. Let me explain, the modern boiler does not simply switch on and off to regulate output, it alters flame height depending on the return water temperature, so the thermostatic radiator valve (TRV) controls flow in radiator and as it closes the by pass valve opens sending hot water back to boiler which then reduces flame height so rooms stays at an even temperature. The other option is OpenTherm which nest supports this allows the wall thermostat to do the same, it does not switch on / off but regulates boiler output, so a low hysteresis.

I don't know which boilers have OpenTherm but know non of my family have a boiler which can use it. So it would seem step one find if your boiler supports OpenTherm.
Next decide how much you want to spend? I would say either cheap like the Pegler Terrier i-temp i30 programmable TRV heads or expensive like EvoHome not really worth going half way.

Although my eTRV can be set so as my mobile phone is within a set distance it will auto turn up the heat, they are so slow getting the room to new temperature it is rather pointless a simple time works better. I found once the eTRV were fitted down stairs the up stairs seemed to behave itself with simple TRV's so only got around to fitting two. I hope I can stop you repeating my mistakes.

So cheap wired programmable thermostats OK but if using wireless don't use cheap ones, look at Nest or Hive or even a proper EvoHome. I did look at a number of other systems after making my error, other than EvoHome most that use eTRV heads still need a wall thermostat monitoring at only one point to control boiler. EvoHome uses the sensors in the eTRV in each room to tell the central controller if the boiler is required, it is a cracking system but also a cracking price, I decided mother will not live long enough to ever get that sort of money back.

 

[gblades]

The anti-hysteresis feature is a pretty standard in all smart thermostats. It has two main components. The first is the heating prediction where it looks at the current temperature and outside temperature and then works out when it should turn the heating on for the house to be up to temperature by the set time. Normally this would turn off the heating before the set temperature is reached to cater for the hysteresis. The other mode is when maintaining the house temperature. It will turn on the heating for a set amount of time and then turn off because it knows it takes a bit of time for the warm radiators to actually heat the room.

The Netamo I mentioned previously has both of these options. The new Worcester boiler I got with their Wave thermostat because it regulates the boiler and is therefore running it more efficiently.

 

[ericmark]

It seems the Netamo is a good thermostat, I am sure there are others.

I made a mistake, I will now admit the Horstmann HRFS1 was a load of rubbish, I don't want to see others make the same mistake. I have since making my errors, and I see getting the MiHome eTRV heads also as an error, found the whole idea of central heating control seems to be a few good products and a load claiming to be good but are in fact flawed in one way or another.

Hind sight and hind sight is easy, I should have played safe and gone for EvoHome, however I tried to do it on the cheap.

Controlling the room is easy, it is the controlling of the system which is hard.

The condensate boiler turned everything on its head. Before the condensate boiler you could have fitted a motorised valve to every room each controlled with a thermostat and wired all the micro switches of the valves in parallel so if any valve is opened then the boiler runs. However when the condensate boiler arrived on the market we then wanted not to switch a radiator on/off but vary the flow so the boiler follows the valves with the flame raising and falling to match demand no simply switching on/off.

So the motorised valve is on/off and the thermostatic radiator valve is variable not simple on/off so we are forced to use the radiator valve, it is the same with thermostats, most are on/off there are some like Nest which do have a system where they can actually tell the boiler to adjust flame height, using OpenTherm.

The problem is finding out which do what, Worcester do a boiler controls explained and it tells one nothing, a simple label saying "hysteresis software included" would tell one which are simple switches and which have some thing extra, but to find out one has to down load the instructions PDF and read very carefully.

I looked at one the other week and at first is seemed the same as EvoHome in that it uses the sensors in the eTRV to tell the thermostat with is not really a simple thermostat but a hub which collects all information then in turns tells the boiler what to do, but as I read more carefully is still uses the old idea of a thermostat in the coldest room.

My own house is simple, open plan, put thermostat between living and dinning room and TRV's upstairs and it works a treat, mothers house with doors on every room and a hallway, very different, living room gets morning sun through bay windows and the temperature shoots up, then evening the sitting room gets evening sun so then that room shoots up temperature wise, so in mothers house the eTRV is required.

The same design but North / South not East / West and the result would be different, Even a garage or fence which masks the sun would charge it. I still can't work out why once down stairs was sorted up stairs seemed to run A1 with simple TRV's I will guess it is the heat raising through the floor?

My house original design one central gas fire, mother house original design three open fires and a solid fuel cooker, there were louvred windows in kitchen to let out the heat even then often cooked with back door open. As far as control goes my first house was best with gas hot air heating ducts took air to every room and vents in doors allowed it to return to boiler whole house was even heat, however blowing air across single glassed windows resulted in huge heat loss so very expensive to run. And of course all rooms same temperature.

 

[KksD]

Midnight and I must be missing something....but someone, please help. How do I put a new post on this platform?