Trying to get head around central heating!

[ericmark]

At night house is too hot, tried switching off central heating with programmer, but then too cold, also tried wireless programmable thermostat which was also a failure, it kept loosing the RF link.


So what I need it seems is a better quality programmable thermostat and it would seem “Nest” is the answer, since this thermostat has two way coms and it can be set to “follow” with the eTRV already installed.

However it will involve some work to install so I want to install it in the correct place.

What I would think will work, is if installed in same room as the eTRV and set to “follow” and placed away from the radiator, then one a cold day the “Nest” will always be colder than the eTRV so if set at nearly the same temperature the boiler will run all the time, which is what is wanted. However on a warm day the “Nest” will be nearly the same temperature as the eTRV so it can be set so it switches the boiler off on a warm day, but not on a cold day. Since the eTRV will “follow” “Nest” then if we turn temperature up or down with the “Nest” then the eTRV will also go up or down by same amount so the system will still work.

Or will it? The question is really what is meant by “follow”? If by follow it means when Nest goes up or down 2˚C then the eTRV will also go up or down by 2˚C then it will work, however if it means when Nest is set to 19˚C the eTRV is also set to 19˚C then it will not, the Nest will never switch off as there will always be a temperature drop between the eTRV and the Nest.

However I can’t find anything in the instructions which explains what “Follow” means.

 

[omega015]

By house is too warm/cold, are you meaning a single room or area of the house? do you have much of a temp dif. between upstairs/downstairs? I'm not sure if eTRV's allows nest to work with multiple zones independently or if this is still only for a single room or if you will have to use multiple apps or some kind of integration for them to work together. Nest website seems to not mention any integration with smart TRV's and simply states its best to control heating with the Nest.

If your wanting to get a nice balance for the whole house, while Nest is by far more stylish and pretty to look at the evohome (and possibly others) Offer far more choice for individual room/radiator/zone temp control. I use the evohome in a 3 bed semi, mixture of brick/breezeblock walls and have zero RF issues between the relay, controller, gateway, thermostats or valves and some of the valves are blocked behind drawers etc... While the setup cost me a bit more than nest and other solutions at the time due to the individual radiator valves I get a comfortable temperature across the entire house and do see some savings in energy usage (instead of the other half turning the house into an oven).

EDIT
The energenie mihome seems to convert the nest into a multi room/zone with use of its smart TRV's. Which probably makes the actual nest thermostat/features redundant and the nest simply becomes an on/off switch for the energenie (haven't fully read how it integrates so I could be wrong)
http://nest.energenie4u.co.uk/

 

[ericmark]

EDIT
The energenie mihome seems to convert the nest into a multi room/zone with use of its smart TRV's. Which probably makes the actual nest thermostat/features redundant and the nest simply becomes an on/off switch for the energenie (haven't fully read how it integrates so I could be wrong)
http://nest.energenie4u.co.uk/

This is my problem, I also haven't read how it integrates, all it says is "Follow" it does not say how it follows.

Up stairs the standard TRV's seem to do a reasonable job, down stairs hall has no TRV I really think it needs one, kitchen has a towel rail which seems is enough, wet room has towel rail and electric under floor heating, latter used to dry floor rather than heat room. So the two rooms which are important are living room and mothers bedroom (down stairs), today is very bad due to Doris (also mothers name) but wind gets through front door and not much I can do, needs to be threshold free for wheel chair, and years ago my dad extended front of house into the porch single brick, there is a sliding door after front door, but drafts are a problem. Added to this down stairs the living room has a bay window and it is a sun trap.

So there extra control is to compensate for the house failings, the eTRV has helped, but the hall radiator is on the wall between hall and bedroom, I assume reason why bedroom is hot is the heat going through the wall. If I turn down the hall thermostat then bedroom better temperature, but in the morning living room is still cold, basic fact hall is not a good place for general thermostat.

When I first fitted the programmable wireless thermostat in the living room it worked reasonably well, but at that time all up stairs radiators were on just frost setting, so when the programmable wireless thermostat started to fail I tried using a pair of eTRV's, not a failure, they do work, but not quite good enough.

As far as I can tell, the Nest thermostat needs some hard wiring, unlike the programmable wireless thermostat the temperature measuring part is not battery powered, so once fitted don't want to move, I think wall between living room and bed room is likely the right place, it's diagonally away from radiator and last place for sun through bay window to hit. And I can then program the temperature to rise at 7:00 am, and drop at 8:30 pm. I would want the eTRV to raise and fall at the same time. The difference between the two would need some experiments, but likely the Nest will need to be set one degree higher than the eTRV judging from the thermometer which now sits where I intend to place it.

This is the problem, if "follow" means eTRV and Nest are the same, then the Nest will control heating rather than the eTRV which means heating turning off and on rather than adjusting radiator temperature.

 

[omega015]

There's almost zero information on how these two work together apart from this "follow" bit of blurb from automatedhome.co.uk This seems to suggest you have 2 options. putting the TRV's in Follow mode has them (or just one maybe?) mirror whatever set point you have on the nest, this does not seem like it makes any use out of the investment and seems rather pointless to me. I assume there's the second option of individual TRV set points that once any TRV needs some heat, the controller sends a message to the nest to switch on the heating. Not sure if some kind of override or if it adjusts the nest set point to match the highest TRV set point.

If you do happen to go down the nest/energenie route be sure to let us know how it works and your findings. I am actually looking at some energenie stuff for the electrics/sockets so I might see how they integrate with other tech as that might also offer some insight.

 

[ericmark]

Thank you omega015 clearly you found same as me, very little info. I do have one double MiHome socket, this one from Screwfix (ElectroFix) it does what I want, it powers the door alarm to alert us if mother opens a door, and extruder alarm rather then intruder alarm. The problem was if I switch it off to go out I needed to switch it back on again so my wife knows if mother is escaping, so these sockets allow that, the other was we have three carer visits per day at fixed times, the socket is programmed to turn off when carer are due. Except for Wednesday and Saturday when mother goes to day care. At first we tried using a simple remote controlled plug in socket, however a few times we forgot to re-set it, so then went to simple timer, but can't reactivate that from outside. So for me it has worked well.

However two small niggles, one is it does not tell you if on or off on phone or PC, you select on and hope it works, so far it always has, and second it only has three timers per day, I expected like the eTRV it would be unlimited, you can select which days of the week the timer works on, so afternoon on Wednesday and Saturday the alarm is not set.

It seems there are also three plug in units, these have three flavours, switching, monitoring, and switching plus monitoring, but it seems the double socket replacement only comes as a switching unit. As to the plug in units again it does not say if when unplugged it retains the program one has set? I looked at the MIHO005 unit and no where does it say how many on/off sequences can be programmed per day, the same with the MIHO007 which I have, it does not tell you how many, but I know it is three.

 

[D_Hailsham]

There's almost zero information on how these two work together apart from this "follow" bit of blurb from automatedhome.co.uk

I have tried searching the automated home web site, but can't find the blurb. Can you post the full URL of the link please.

 

[omega015]

This was what I saw about the "follow" option: http://www.automatedhome.co.uk/new-...alexia-amazon-echo-support-to-nest-ifttt.html

 

[D_Hailsham]

Having read the link, I would assume that "follow" means the TRVs target temperature is always the same as the Nest target. If the Nest is set to 20C, the TRVs will automatically set to 20C; and if the Nest is turned up/down 1 degree, all the TRVs will get turned up/down the same amount.

I notice the devices use the 434MHz band, not the 800MHz. I wonder why that is? All the big manufacturers (Honeywell etc) moved away from the 434MHz band years ago as it was not reliable enough.

 

[ericmark]

430Mhz to 440Mhz up to 40W I am allowed to transmit. I would think that would cause a problem, 433,600 to 434,600 is all modes, so yes it does seem a bit odd to use a shared frequency with such a small power.

As to the follow I see a problem, living room target 19 current 21 independent thermometer 23.5 and bedroom target 17 current 20 independent thermometer 20.1 it is degrees centigrade but that hardly matters, want the radiator thermostatic valve to control first, only when the sun comes out do we want the thermostat to switch off boiler, until that point want the eTRV to do the work.