System Boiler (Y-plan) with Google Nest 3rd Gen and OpenTherm?

[hometech]

I have one customer who has done the above. He has used his professional technical knowledge to access the Honeywell Evohome wireless network that controls his wireless TRV's. He built an app that allows him to track everything. It must have taken him a very long time and he was rightly proud.

However, 99.9999% of people just want it to work, maybe save them some money and not have to think about it.

Boilers modulate, controls do their thing and manufacturers are always concerned about giving access to their products. Especially if it can turn into a bomb or poison you in your sleep.

Is this what is know as the Jihadi plumbing defence LOL. Please explain how a boiler becomes a bomb with the added ability to poison while you sleep. You don't write the Russian stories for the BBC by any chance?

 

[albert85]

To attempt to answer your original post regarding the circuit for opentherm, my immediate reaction on reading the Nest manual you linked, was that the opentherm connections on P24 are to be used in addition to all the other connections for the system (in your case Y-plan on P23). This seems to be borne out by a thread (but S-plan) I've seen, but some people who have done this have had trouble with demand for hot water only not firing the boiler. Might be worth looking through this (admittedly from a few years ago):

Thanks Basher for digging that out.

From that thread it sounds like if I configure the Nest in on/off mode for hot water, and in OpenTherm mode for central heating, I might be able to get it working, so long as the Ideal Logic+ system boiler can sensibly handle switched live (on/off) and OpenTherm inputs at the same time.

Regarding 'sensibly handle' multiple inputs, the questions to understand I think are what happens if:
a) Nest is calling for heat via switched live and not via OpenTherm. I assume the boiler will prioritise switched live at that point and fire on the flow temperature configured in the boiler.
b) Nest is calling for heat via OpenTherm but not via switched live. I assume the boiler will then fire on the temperature requested via OpenTherm.
c) Nest is calling for heat via both OpenTherm and switched live at the same time. I assume that in this case switched live will be prioritised and the boiler will fire on the flow temperature configured in the boiler.
d) Nest is not calling for heat via either interface. I assume boiler will stay off as expected in this case.

I've asked Ideal support to clarify how their Ideal Logic+ system boiler specifically will handle these four scenarios and will update here if I get useful input from them.


@hometech thanks for pointing out the DYI option with the raspberry pis. It sounds like a fun project but I'm still looking for a more accessible setup so it can be serviced by most heating engineers without my input. Else my house will have to come with its own GitHub repository if I ever decide to sell it...

 

[hometech]

Thanks Basher for digging that out.

From that thread it sounds like if I configure the Nest in on/off mode for hot water, and in OpenTherm mode for central heating, I might be able to get it working, so long as the Ideal Logic+ system boiler can sensibly handle switched live (on/off) and OpenTherm inputs at the same time.

Regarding 'sensibly handle' multiple inputs, the questions to understand I think are what happens if:
a) Nest is calling for heat via switched live and not via OpenTherm. I assume the boiler will prioritise switched live at that point and fire on the flow temperature configured in the boiler.
b) Nest is calling for heat via OpenTherm but not via switched live. I assume the boiler will then fire on the temperature requested via OpenTherm.
c) Nest is calling for heat via both OpenTherm and switched live at the same time. I assume that in this case switched live will be prioritised and the boiler will fire on the flow temperature configured in the boiler.
d) Nest is not calling for heat via either interface. I assume boiler will stay off as expected in this case.

I've asked Ideal support to clarify how their Ideal Logic+ system boiler specifically will handle these four scenarios and will update here if I get useful input from them.


@hometech thanks for pointing out the DYI option with the raspberry pis. It sounds like a fun project but I'm still looking for a more accessible setup so it can be serviced by most heating engineers without my input. Else my house will have to come with its own GitHub repository if I ever decide to sell it...

Your boiler has a manual, why not your home?
I would suggest you look around your locality for a raspberry pi club. There are lost of 10yr olds who could do this for you. Its really very simple stuff but it looks like magic to the those who never use a multimeter lol.
Is your boiler a sentient being? How would it handle two instructions simultaneously but being able to decide which one to choose?
The nest instructions are for an S plan OR Y plan OR opentherm...its not a pick and mix lol

 

[albert85]

Had a reply from Ideal. Sounds like with their boiler its not possible to use OpenTherm and switched-live at the same time.

Response from Ideal support: "if you was to have both controllers wired in each terminal then boiler wouldn’t fire as the link would be broken in the circuits, the only way the links would be made on either switched live or open therm would be to have a demand on. As stated earlier, if this was to be the case then the switched live would take priority making your open therm void."


For future readers, I can confirm that in my Nest settings when setting up a system boiler,

• I first get to pick if heating should be controlled with OpenTherm or on/off
• If I pick OpenTherm (see attached first image), I then get to pick if I want hot water to be controlled via 'OpenTherm' or 'on/off' or 'not controlled' (see attached last three images)
• And if I pick the heating to be controlled via 'on/off' then the offered hot water control options are either 'on/off' or 'not controlled'

And judging from the thread linked by Basher the Nest seems to output as you would expect from these settings. Just thought I'd leave that hear in case it helps someone

 

[hometech]

Raspberry-Pi Home Heating Controller

Raspberry-Pi Home Heating Controller: Have you ever wanted to remotely control your home heating and hot water from anywhere, but did not want to pay over £200 for a commercial system ? Using off-the-shelf hardware and shareware code, you can build your own DIY controller for less than …

www.instructables.com

 

[Jerry]

Is this what is know as the Jihadi plumbing defence LOL. Please explain how a boiler becomes a bomb with the added ability to poison while you sleep. You don't write the Russian stories for the BBC by any chance?

Are you high?

 

[Jerry]

Your boiler has a manual, why not your home?
I would suggest you look around your locality for a raspberry pi club. There are lost of 10yr olds who could do this for you. Its really very simple stuff but it looks like magic to the those who never use a multimeter lol.
Is your boiler a sentient being? How would it handle two instructions simultaneously but being able to decide which one to choose?
The nest instructions are for an S plan OR Y plan OR opentherm...its not a pick and mix lol

Go and find a 10 year old! What an answer! You sound like Groucho Marx

You are disconnected from reality.

It's so easy. All you have to do is buy rasperbby pi. Learn how to turn it on, connect it to your computer and you are away! No learning the computer language you can just download the prewritten scripts made by 10-year-old (who looooooove boilers and heating. So much better than Fortnight). You won't have to learn, stress, swear and scream at this tiny little computer at all. It will all be fine and easy and plain sailing. Figuring out a multimeter will be the hardest part. It will be the only doohickey you have to buy and you can easily do it in an evening.

You have no idea what you are talking about. Please stop lying to people. The more you write, the more ludicrous you sound.

TO THE ORIGINAL POSTER - if you really want to go down this route, I have a lot of respect for your desire to understand and control your heating system. Please be aware the cost/benefit ratio will be in the negative. BUT, you will learn a lot along the way.

HOMETECH - please stop misleading people. I am sure you have a wonderful heating system but what you are so flippantly discussing is beyond the reach of nearly everyone. Including nearly every registered insured qualified experience profession heating engineer who does this for a living. I pity the person who comes to service your boiler.

 

[Basher]

The nest instructions are for an S plan OR Y plan OR opentherm...its not a pick and mix lol

if you are correct, please could you explain how Nest can control the heating and hot water when its internal switches are not connected to anything (as per the Opentherm schematic on P24)?

 

[Jerry]

Raspberry-Pi Home Heating Controller

Raspberry-Pi Home Heating Controller: Have you ever wanted to remotely control your home heating and hot water from anywhere, but did not want to pay over £200 for a commercial system ? Using off-the-shelf hardware and shareware code, you can build your own DIY controller for less than …

www.instructables.com

You are insane mate.

Let me just copy and paste a little of the instructions for everyone to read:

Software :

Connect to each pi-heating-sensor in turn,

ssh [email protected]

We can now start to install the packages and software that will read the 1-wire thermometer data and make it available the the heating controller hub.

again there is a script to do this :

curl "https://raw.githubusercontent.com/JeffreyPowell/pi-config/master/pi-heating-remote-install.sh" > pi-heating-remote-install.sh && sudo bash pi-heating-remote-install.sh

once everything is installed, reboot :

sudo shutdown -r now

now we need to edit the config file ~/pi-heating-remote/configs/sensors

but first we need the discover the serial numbers of the connected 1-wire thermometers

ll /sys/bus/w1/devices/

Will show that I have two 1-wire thermometers connected, 28-0000056e625e and 28-0000056ead51.

drwxr-xr-x 2 root root 0 Jan 25 15:23 .

drwxr-xr-x 4 root root 0 Jan 24 16:17 ..

lrwxrwxrwx 1 root root 0 Jan 24 16:43 28-0000056e625e -> ../../../devices/w1_bus_master1/28-0000056e625e

lrwxrwxrwx 1 root root 0 Jan 24 16:43 28-0000056ead51 -> ../../../devices/w1_bus_master1/28-0000056ead51

lrwxrwxrwx 1 root root 0 Jan 25 15:23 w1_bus_master1 -> ../../../devices/w1_bus_master1
Now edit the config file and insert these serial numbers.

vi home/pi/pi-heating-remote/configs/sensors

Delete the default settings and insert the serial number and a name for each 1-wire thermometer.

remove all this :

28-000005cf873e = External

28-000005d0065c = Conservatory

28-000005d01a5a = Conservatory Rad
and add your data, e.g. :

28-0000056e625e = Lounge

28-0000056ead51 = Garden
save and close the config file.
​

Did i mention there was soldering involved?

Muppet

 

[albert85]

I don't find the DYI option ridiculous thats why I thanked hometech for suggesting it

I have a physics degree and develop software at work, so it would be a fun project for me and totally within reach, as it will be for thousands others.

As a software engineer I'm also keenly aware of the responsibilities that come with maintaining legacy software for many years. With that said I don't think it would be too hard to set it up in a way where there is a straightforward way to convert it back to the well known on/off system if desired at any point.

Anyway, for me personally I've decided I want something more off the shelve where I can pay a heating engineer to maintain it, but I could totally see myself make a different choice in the future

The more options the better