Does a wireless TRV bring the boiler on?

[ericmark]

It does confuse me, the problem is until you buy and fit a device one is not sure what it will do. However to me whole point of having eTRV heads is that each room is individually regulated, some have no electrical connection with the boiler, the only connection is through the temperature of the return water, however most do report the set and current temperature so actually do transmit what is required to switch boiler on and off.

The big question is how to connect the boiler to the eTRV head? Some have it all ready made like the EvoHome however even EvoHome has a thermostat option, not really sure why? Others need some device to actually do the switching, theory it could be a simple relay, and there is no reason why an IFTTT app could not be written to switch on a relay when any valve head shows a target above actual temperature.

However as far as I can see for the app to work, the internet also needs to be up and running, this is one of those bits where not sure what happens? But it does seem the apps are on a central server, so no internet and no app. As to connection between Nest or Hive and the eTRV head, this also seems to use the IFTTT system so again no internet and no hand shaking.

Even with hand shaking, it seems either Nest or Hive follows the eTRV head, or the eTRV head follows Nest or Hive, but the whole idea is that each room is individually controlled.

I had every intention of fitting nest, however now I simply can't see how it will help? Yes I want something to turn off all heating at night, or at least reduce the temperature to a low setting. As it stands I have two options for the non eTRV head controlled areas, I have a programmer which can turn off the thermostat in the hall, and I have a programmable thermostat on the oven carcase in kitchen which can also switch heating on and off, used as a frost stat in the main. Although the kitchen thermostat is useless when the oven is in use, Christmas day is only time over used over night so not really a problem.

So I simply can't see how adding extra hardware will help me? OK the nest should learn, but really how does that help? the existing thermostat in the hall is there for one thing, to turn off central heating when the weather gets warm, it is simply there to stop house getting too hot, it does NOT control the temperature of any room, including the hall, that is controlled by the TRV on the hall radiator. All the thermostat does is switch off the central heating in the summer.

Even that is not really needed, it could be a simple on/off switch, when summer comes I don't want the central heating firing up, even on the odd cool day, temperature is controlled by opening or closing windows, I don't want a cold draft starting the central heating, it's switched off.

So since the thermostat does so little, why get any special one?

 

[bernardgreen]

Eric. For what it is worth,

When a family lost the internet connection ( cable fault in the street ) their heating system became erratic until the cable fault was repaired. Co-incidence ? Seems not as there were two periods of no internet acccess which was when the heating system was erratic., I got this third hand with no information about what equipment was involved.

 

[ericmark]

I think that if the eTRV is set then it would continue to alter temperatures as programmed even without the hub, never mind internet, the wall sockets and light switches do remember what was set within the switch or socket so would guess eTRV would do the same. If never set they will control to 16°C, pressing the grey push button and holding it in for two seconds boosts the eTRV to the comfort temperature setting (21°C) for one hour. This is with no programming this is default setting.

The problem is when using the IFTTT apps, these do need internet to work, and the linking of the Nest and the MiHome Energenie eTRV's is done with IFTTT apps.

One can hear the valves working, and when set to change from high to low or low to high they do not auto fully open or close, but do a little bit at a time over something like an hour, so although there is an app so it can sense your phones distance from home so when you get within a set distance it turns up the heating, it is so slow changing temperature unless you work over 100 miles from home it is not likely to heat it up in time.

In fact in the morning moving from 16°C to 20°C starting at 6 am it is not to temperature by 8 am, so I cheat, at 6 am it moves to 22°C then at 8 am back down to 20°C and with that setting it works.

What seems odd, to get down stairs to maintain set temperature I needed the eTRV, however up stairs works A1 with standard TRV heads, I assume it is the heat raising from down stairs which assists up stairs, but up stairs the standard TRV heads work fine. But down stairs the standard TRV allowed the two rooms both with bay windows which does not help to get really hot some times of day yet cold at other times, as the sun shines through the bay window the standard TRV was too slow to react and the room would over heat.

Of course with a standard TRV they are not marked 12 ~ 27°C they just have 1 to 6 which unless set at night when there is no other heat into the room are at best hit and miss, since it was my wife and I up stairs I started at 1 and slowly increased the setting until to our liking, no thermometers required, but for my 92 year old mother down stairs it was a different story, she will complain it's cold when room at 27°C and we have opened the windows to cool down, the thermometer is a must, when we see it showing 20°C or higher we tell her it's warm enough she seems to have lost the ability to judge temperature. When the central heating thermostat failed we found her with room at 14°C and not complaining she did not realise it was cold. Once the central heating is required the eTRV now really does a good job. However if I was doing it again I would fit the stand alone type. OK I can check her room temperature from this PC, at moment 18°C but baby alarm in her room is also telling me her room is a 18°C so don't need a PC to check on the temperature in her room. At moment all central heating is off. Up stairs is warmer 21.4°C in my room even with window open at 5:16 am outside it's 10°C.

 

[^woody^]

Just to update, apart from the Honeywell Evohome system, the Drayton Wiser sysyem will allow individual radiator thermostats to bring the boiler on, and I'm sure Tado does too, but am just waiting for confirmation.

The more I've looked into this, the more I am convinced that any so called "smart" thermostat or system that does not have individually controlled radiators that will activate the boiler, are not really smart but are pretty dumb and offer little practical value apart from being able to set your heating once a year while you are on holiday thousands of miles away.

Likewise the more I see that having a systems where each room can be its own zone and can have total individual control of the boiler, the more attractive it becomes.

 

[d000hg]

As the cold weather has arrived and our house gets down to 10C by mid-afternoon with no heating, I am thinking about this again. The ability to turn rooms on/off is seeming attractive - we have a large house with many rooms and no guarantee which ones we'll want to use when.
Being able to set it so every room stays at 14C minimum 24/7 and I can then decide which room(s) to heat to 20C on the fly would be quite nice... typically we only use 2 rooms at a time.

 

[ericmark]

Other than EvoHome and some really expensive building management systems they all seem to have the same problem, how to control the boiler.

However the question is do we need it to control the boiler? Unless the boiler has something like OpenTherm you can only turn the boiler on/off with an electric connection. However using the return water temperature it will turn flame height up and down, only when it can't turn down any lower will it start to cycle.

So if all you have is a programmer and TRV with no thermostat at all then heart of winter everything will work fine the TRV controls the rooms and the boiler is controlled by return water temperature.

The problem is as summer returns the boiler will start to cycle, so you have to manually turn it off.

In a large house with many rooms you select the coldest room with no alternative heating and no outside doors and thermostat goes in that room. In the smaller house it is a problem finding such a room. There are thermostats which can work on a average of 4 rooms, however can't really see how this helps if any room is cold you want boiler to run.

So the cheapest programmable hard wired thermostat is around £24 so select 2, 3 or 4 rooms and fit thermostats wired in parallel then if any of the key rooms demand heat the boiler runs, you can fit a cheap TRV head also programmable so each room £22.51 for TRV head and £23.72 for programmable thermostat so £46.23 per major room plus wiring, with wireless the price of thermostat rockets, cheapest around £47.46 (all Screwfix prices) and the receivers may interfere with each other, in this house if I had just two programmable wall thermostats and two electronic heads for the TRV it would work, for other rooms no one is really worried if a little two cold, as long as two major rooms OK.

The problem is installation cost of wired thermostats, in this house it is the moving of furniture to gain access, so not done it, However I have two wireless thermostats, not perfect but good enough, and two electronic TRV heads, every other room has standard TRV which is good enough. Every so often I do turn heating up, I use the programmable thermostat to turn it up so next program it auto turns down again, not perfect but good enough.

 

[dave1w]

I’ve just had a new boiler installed, Vaillant, and am controlling it with a NEST currently. While it was a big step up from the simple mechanical timer we had before, it’s actually pretty basic and just lets us set the times etc. that we want the boiler on. Unfortunately Vaillant have kind of kicked down the smart control side of it to their own system.

At the moment I bought some programmable TRVs from a site in Germany, and use them to switch if the bedroom radiators during the day and most of the downstairs radiators off at night.

I’m planning to get the wiser system with a couple of TRVs to put into the kids bedrooms to start with, with the times TRVs turning off the rest of the house rads during the night so at least we can maintain the kids rooms comfortably, with the eTRVs starting up the boiler when needed.

We have UfH going in in our extension, but Wiser doesn’t yet work with UFH, so probably going to hold off for now, until it does.

I think it would be £199 for the Wiser 4 channel kit, the £35 per radiator. Much cheaper than eco home, but it would soon start to mount up as you add more and more TRVs

 

[dave1w]

Sorry 3 channel kit

 

[SimonH2]

I’ve just had a new boiler installed, Vaillant, and am controlling it with a NEST currently. While it was a big step up from the simple mechanical timer we had before, it’s actually pretty basic and just lets us set the times etc. that we want the boiler on.

When we moved, I found that there wasn't a thermostat at all. I've put a Salus RT500 in, and really it's a great step up. It doesn't work like a stat+timer - it's a multi-temperature stat. 5 settings per day, and for each one you set the time plus the setpoint to go to. So instead of just switching off, it can set back to a lower temperature - so easy to set a lower temperature overnight and during the day, but without switching off altogether.

Also, it's a doddle to use if you want to alter the temperature. Just hit the up or down buttons and change the setpoint - and that stays in effect until the next programmed time when it resets to the programmed temperature.

Unfortunately Vaillant have kind of kicked down the smart control side of it to their own system.

I think they've done like others and gone down the route of closed proprietary controls.
Mum had a new Vaillant installed in her last house and I asked Vaillant how to set it up to have different temperatures depending on whether the hot water tank is being heated - needs to be set high for that, but that's far too high for the rads. They came back with needing one of their weather compensation controller systems to do it

 

[ericmark]

I thought Vaillant supported OpenTherm? Nest and EvoHome are OpenTherm so either should work well. Nest is not as good as EvoHome but cheaper, and it works with Energenie TRV heads.

 

[dave1w]

In the UK apparently it doesn’t. As I understand, in Holland you can get a board that lets you use opentherm, but in the UK it isn’t supported, so you need their own control