Nest Thermostat Query

kev2009

Thanks, ill give it a week and see how its going then

Kev

Le_Kirk

Ibrahim5 said:

I had a Siemens with PID control which was pretty good at keeping the temperature constant. 

Oh, that brings back memories, the Proportional, Integral, Derivative temperature controller.  I spent hours as a young service engineer setting these up for customers (large industrial ovens) and then their own staff would come along and change things because "they knew better" except they didn't specifically that it took a while for things to settle down and for the system (house boiler or industrial oven) to acclimatise to the settings.  I could spend a whole day taking readings every 20 minutes, making calculations and then altering one setting before going back to taking readings.  Oh, how we danced up and down with joy when temperature controller manufacturers brought out the "Auto-learn" facility.

getmore4less

Most of the compensation features are available on standalone(cheaper) units as well.
Including holiday modes and setback temps.

The main advantage of the smart option then becomes remote access and potentially better interface than on the box to change settings.

They probably use an off the shelf standard IC these days with a bit of memory to store the history

I have a different system(Owl) but they are mostly the same as long as you have enough time/temp options.

The trick is to set target temps for the time you want and let the system adapt
On mine I can set max startup and cool down times.

We use a background setback temp of around 15c when using the property as we find that ok for say night time.
reheat times are OK with that. 

When away for longer periods the fall back is frost protect.

if the property has got down to say 10c you can get the air upto temp quite quickly but if the heating goes off the fabric of the building sucks the heat away and temp drops quickly. (it does not really suck but that describes the effect)

Have to be a bit careful with the restart as it can take ~24hr to get to steady state due to the thermal properties of the building so we turn it on the day before return if we think it will get below 15c, can override remotely if needed.

Owl is on a subscription now but I have not found a system that has the same hot water control,  you can set time/temp windows just the same as heating as it has a proper tank thermostat 


If you can capture the real time temp and status you can do your own graphs.
Someone will have done it for home automation.

Might be something you can grab and use standalone for the Nest.



  

moneysaver

[Deleted User] said:

Not sure why you would invest in an expensive Nest thermostat and then turn off all the smart features that you've paid for and more importantly save energy / money.

The true radiant mode means you don't have to worry about what time the heating comes on, you just set it that you want the house to be 19C at 7am when you get out of bed and it works out whether it needs to put the heating on at say 6:30am or 6:50am.

The true radiant mode also understands the overshoot that occurs when the set temperature is reached and will switch of at 18C because it knows the latent heat in the system will take it up to 19C anyway.

Both save energy and still give you exactly the temperature you need when you need it.

I know exactly how it works. I was on to tell the OP the options.

I do not need a lecture on what I spend my money on. My car is loaded with tech and I do not make use of all of it, Is that a waste too?

 Some options on the Nest Do not work for me due to my work schedule. Until my schedule changes  I will turn off certain options.

Moneysaver

Neil_Jones

kev2009 said:

Thanks, yes, I've left the true radiant on, only turned off the auto schedule as I want to set that myself.  My concern is the system turning it on and costing more to keep the house at X temperature so I've now set it 30mins later so that it doesn't come on too early.
It's a shame the history part of the Nest thermostat doesn't give you a list of times it came On/Off, instead the little chart where if the items are close together its hard to see the times.

Still getting used to it here.  Keep changing the settings which prob isn't helping the learning part

The big advantage to this system is being able to adjust/turn on when not at home i.e. when on hols, set temp lower BUT if it got real cold, I'd often thing maybe I set it too low but now I can just increase it etc to suit and also ensure is up to normal temperature when I'm returning home

Kev

The radiant thing doesn't affect the running costs, it'll just be more intelligent about it.  Pointless firing up at 7am regardless (which most "dumb" systems will) when its half a degree below  at 6:55am, and likewise if you set the "off" period at 9am and its already at temperature at 8:30am, it'll probably shut off because it thinks hey, its warm enough already, I'm turning this off now.

You can always override in any event.

kev2009

Yes thanks.  I changed the time today and it still came on at the same time so I've changed it to later to see what happens now as not sure if its picking up my changes to the schedule.

One downside I'm seeing already is I have no idea when the heating is being turned on unless i either am in close proximity to the boiler to hear it come on or I keep checking the thermostat as the screen is off most of the time.  My old system used to show a red light when it was on so I got a visual indication, with this one i have to get near the thermostat to be able to tell, wish I could set the display to always on or have it send me a notification when heating was turned on/off so I'd know.  Granted notification would getting annoying but would be good to ensure system is working for a couple of days and then when i know its doing what i want, then turn off notifications.

Kev

[Deleted User]

Neil_Jones said:

kev2009 said:

Thanks, yes, I've left the true radiant on, only turned off the auto schedule as I want to set that myself.  My concern is the system turning it on and costing more to keep the house at X temperature so I've now set it 30mins later so that it doesn't come on too early.
It's a shame the history part of the Nest thermostat doesn't give you a list of times it came On/Off, instead the little chart where if the items are close together its hard to see the times.

Still getting used to it here.  Keep changing the settings which prob isn't helping the learning part

The big advantage to this system is being able to adjust/turn on when not at home i.e. when on hols, set temp lower BUT if it got real cold, I'd often thing maybe I set it too low but now I can just increase it etc to suit and also ensure is up to normal temperature when I'm returning home

Kev

The radiant thing doesn't affect the running costs, it'll just be more intelligent about it.  Pointless firing up at 7am regardless (which most "dumb" systems will) when its half a degree below  at 6:55am, and likewise if you set the "off" period at 9am and its already at temperature at 8:30am, it'll probably shut off because it thinks hey, its warm enough already, I'm turning this off now.

You can always override in any event.

Modes like true radiant do save running costs, you need a different mindset to understand modern smart thermostats / programmers.

You no longer think in terms of what time you want your heating to switch on, you think in terms of what temperature you want the house to be at a certain time.

Let's say you get out of bed at 7am and want the house to be 21C when you get up.

Old thermostats / programmers you would probably set the heating to come on at 6:30am and at some point after that the house would reach 21C - could be at 6:40am, could take until 7:10am on a really cold day - but you have no idea when it will be.

With a smart thermostat with something such as True Radiant mode you set the temperature to be 21C at 7am and the thermostat decides when to turn the heating on based on it learning how long it takes for the house to heat up from specific internal and sometimes external temperatures.

So instead it may switch the heating on at 6:50 am if it is already 19C and the next morning it will switch it on at 6:30am if the house is really cold at say 16C. Either way it is aiming to get the temperature to 21C at 7am and will switch the boiler on as late as possible to achieve that temperature.

And this is where it saves money, on the warmer mornings the heating switches on later so it saves energy. Either way you end up with 21C at 7am every single day and that's all that matters, not what time the boiler comes on.

When it comes to the end of the schedule, say from 11pm you have set it to drop from 21C to 16C, it will be sensible and not switch the boiler on at 10:50pm just because the temperature has dropped below 21C because it knows it will be wasted energy. Dumb thermostats would still trigger the heating and waste energy.

Then there is the overshoot compensation that saves energy. Old thermostats "click off" when the temperature reaches say 21C but all the heat that is in the radiators continues to heat the room to say 22C - wasting energy.

A smart thermostat learns about overshoot after a few days and knows it is ok to switch the heating off at 20.5C because it will rise to 21C anyway in say the next 15 mins - so again it saves energy.

Also they often use shorter firing intervals for boiler - essentially turning it on and off more regularly to ensure that the return water to the boiler is as cold as possible which maximises efficiency in condensing boilers.

Even better, with an OpenTherm boiler it will actually regulate the water temperature going to the radiators to find tune the heating even more and will can raise and lower the water temperature if needed instead of cycling on and off to fine tune the heat delivery.

I've said above I don't have a Nest thermostat but I have and ESI wireless smart thermostat that has all those above functions equivalent to true radiant mode, the manufacturers bumpf claims 10% energy savings and I can well believe it because I've seen it in action.

anotheruser

Have you got a smart phone?
Have you downloaded the app?

With the Hive, you can set up the thermostat timer like an older "traditional" thermostat.


In this example, the current day selected is Monday.
The person wants their home to be at 17°C between 06:30 and 08:30.
The heating will be off between 08:30 and 12:00.
The heating will be off between 12:00 and 14:00.
The heating will aim to get to 10°C between 14:00 and 16:30.
The heating will aim to get to 18°C between 16:30 and 22:00.
The heating will then be off overnight between 22:00 and 06:30 the following day - Tuesday.

While quite a lot of different timings, you can have less.

The Hive can also learn and start the boiler earlier than 06:30 so by the time 06:30 arrives, the heating is at 17°C instead of starting at that time.  I don't have this feature on as I don't require it.

I would like to think Nest has the same sort of scheduling, so set it and leave it.  You shouldn't need to worry about whether the heating is a couple of degrees more - remember, as soon as the 17°C warm air reaches the thermostat, it'll tell the boiler to shut off.  However as others have said, the room temperature is likely to increase a little further as the boiler isn't likely to turn off immediately and the hot water will still be pushing through the radiators.

I don't know if the Nest thermostat has any indicator lights on it.  The Hive one doesn't (the screen is off unless I push a button) and I don't really care if the boiler is on or off as I have already set the schedule to what I want.  If I'm a bit cold, I can always boost the boiler for an hour.  But if I really want to know, I can look at the app, which says "heating" in the top corner when the boiler is on.  But I can tell as our boiler is in the kitchen so I can hear it slightly and I can feel the warmth.

Stop messing about with the timings and just set the schedule for what you want (you should be able to copy this to other days or set other days to be different).  Then you don't need to worry about it and just boost the heating ad-hoc if/when you feel the cold.

When you get these basics down, you can start realising the true effects of smart heating, like having it fire the boiler when you're 5 miles away from the house for example.

kev2009

Thanks, adjusted it to a bit later yesterday and now its not coming on as early so goign to leave as is now and see how it goes after a few days.
Thanks all

Kev

kev2009

Hi all,

Could anyone advise how I can find out the MAC address of the Nest heat link?  Looking on my router, I can see all the devices connected to show what IP, mac address they are etc but I can only see my Nest Thermostat and the Nest Protect smoke alarm.  The heat link isn't showing up at all.  It is all working ok, I just wanted to see it on my list and name it accordingly so I know what it is as makes it easier to locate and investigate if issues.  

Looking on the nest app, i can see the technical info for the thermostat which gives me the mac, IP for the thermostat but for the heat link no IP or mac address is listed.  Any ideas?

Thanks

Kev