Smart heating options

Hardware
1

Hi,

this is going to be a long post so I apologise in advance, but the essence of it is that I would like to ascertain my options regarding smart heating, and while I’m a software engineer and can handle that side of things no problem, the hardware side I am far worse at and have basically zero knowledge on heating systems.

The situation at the moment is, I bought a house recently (in Ireland) and my house (built around 1999) has a gas boiler that heats both the house via radiators, and the water via a cylinder.
There is a Danfoss programmer controlling both of these (not sure the exact model, but looks like a Danfoss CP715 Si based on trying to search similar ones on the internet).
There is also a Danfoss thermostat (again based on searching the internet my best guess would be Danfoss RET M) that controls the heating.

So what I ultimately want is a system that integrates into my Home Assistant setup and I can control from there.
The specific things that I want though are:

  • Needs to be 100% local, it can be wifi and have internet stuff so long as it works 100% without that, as I will be blocking it from accessing the internet on the router
  • I would very strongly prefer if it would be both smart and dumb, by which I mean, if my Home Assistant and/or network goes down, I’d like to still be able to have at least basic heating, even if it’s just very dumb fully manual heating by pressing a button to turn the heating on and pressing it to turn it off

Additionally, some of the radiators in my house do have a valve on them to adjust the heating, but some don’t. I don’t know if it’s possible to add these valves, there are some caps that look like they might be there to hide the connection point for a valve, but I don’t know how to find out if that’s the case.
Ideally, I would like to be able to have control over temps in individual rooms as well, though this is not a requirement.

Right now, the boiler is a fairly old one and I will need to replace it at some stage, it’s mostly working still, but has started to show its age.
Additionally, while I’m doing that, I would be very happy to replace it with a combi boiler instead so I don’t have to deal with a cylinder (for my needs, a cylinder doesn’t make a huge amount of sense as it can be hard to anticipate the amount of hot water I’ll need so heating the cylinder overnight ends up being inefficient overall).

So now comes the part where I ask for help. I’m feeling a bit overwhelmed with all of the details here, does the boiler affect the rest, do I need to just put TRVs on radiators and not mess around with anything else to get it smart, are there even options that are both smart and dumb at the same time, …
So I’d like to get some help on this.

I’ve considered also an option of simply making the existing system smart by doing something really dumb like placing a couple of fingerbots to control the programmer and putting a camera or some sort of sensors on the programmer display so I can get status info. Surely there’s a better way, but I’m open to this option as well :slight_smile:

So with all that context here, I’m going to ask a few questions to try and make this post a little easier to action, but I definitely have lots of missing knowledge so if anyone has comments rather than answering the below questions it will be much appreciated.

  1. Is replacing the boiler something I need to consider in this (as in, if I switch to a combi boiler does that somehow mean potentially a thermostat or something I go with will become incompatible)?
  2. Can any radiator take a smart TRV even if there’s currently no knob on it to adjust?
  3. What would be a good option for fully local, dumb/smart devices for this? Maybe if the answer to 2. is yes an option is to put TRVs on all the radiators and set the programmer and thermostat to always be on, but then I’d still have the boiler on all the time which I don’t want so I guess I still need a way to deal with that, but not sure what would be a way to deal with that then while retaining the dumb/smart thing

Appreciate any thoughts, comments, …

2

Not sure if this is local but this was one of the videos I saw a while back that comes to mind for your project.

and it looks to have a HA integration:

3

Your post has a lot of excellent detail, and I’ll take a deeper look later when I can focus more. However, I wanted to jump in because boiler-related topics in Home Assistant (HA) often bring up fascinating challenges and opportunities.

Boiler System Complexity

There are multiple styles of heating equipment, each with unique demands:

  • Single Stage: On/off functionality.
  • Dual Stage: Allows for partial or full heating based on demand.
  • Variable: Modulates output to match the precise heating demand.

For multi-zone systems, especially with radiators or in-floor heating, ensuring the system can adjust its output based on demand is critical. Variable systems, for example, often use advanced communication protocols, but there are controllers available that can bridge simpler on/off thermostats into these systems.

Key Points for Your Setup

  1. Boiler Considerations:
  • If you’re replacing your boiler with a combi boiler, you’ll likely simplify your setup since you’ll remove the cylinder. This won’t necessarily make your current or future thermostat/controls incompatible, but it’s worth confirming with the boiler manufacturer or installer.
  • Modern boilers, especially heat pumps, offer impressive energy efficiency and flexibility. They often integrate with smart home systems for finer control.
  1. Radiator TRVs:
  • Most radiators can take smart TRVs, even if they currently don’t have knobs. Many TRVs are compatible with a range of radiator valve fittings. You’ll just need to verify the specific type of connection (e.g., M30 x 1.5 is common in Europe).
  1. Smart/Dumb Hybrid Controls:
  • One effective solution is to leave the boiler on a base schedule (or set it to always on), then rely on smart TRVs to manage individual room temperatures. However, you’ll still need a central device or automation to prevent the boiler from running unnecessarily.
  • A great option is to pair TRVs with a thermostat/controller like the Tado or Home Assistant-compatible Zigbee thermostats. These systems allow local control, even if the network or HA is down.

Heat pumps are increasingly being used for water and heating systems, and they can provide both efficiency and flexibility. If you’re considering a boiler replacement, it’s worth looking into.
In some cases, outdoor temperature sensors and advanced trim settings can optimize boiler operation further, reducing energy waste.

There are a lot of paths to take when integrating a boiler with HA, so your progress will likely involve some trial and error. Please do keep us updated on your journey, as these specific HVAC setups often lead to some great solutions and lessons!

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oh the horrors I’ve seen

4

I use Honeywell’s Evo Home with the excellent ramses_cc and ramses_rf integrations for HAOS

5

Well a post where an answer could take at least a month to write.

I’ll summarize my takes from very superficial searches.

  1. your current boiler seems to be piloted by some sort of relay (hidden inside the thermostat and/or inside the control panel) so it’s just a matter of finding the rights pins and you can swap it for a smart relay. Coupled with a wireless temp sensor you can do all the automations in ha

  2. TRV can usually be fitted on almost all radiators, you may have to call a plumber to change the valve base if the currently installed don’t support TRV (usually there must be a pin on the valve that the TRV pushes to close the flow on reaching the desired tem)

  3. if you choose to change the boiler I’d try to find something that can be integrated locally in HA (opentherm compatible or ebus compatible)

  4. in your journey try to keep the appliances (boiler, TRV etc) as autonomous as possible and do with HA or other automations only “smart things “ like integrating other info sources to decide what to do, eg. time the increasing of the house temp based on how much time you’ll take to get back from home. But if you leave your phone at the office you should find a home that is at least basically warm, not a concrete igloo.

HVAC system is mostly hardware related, so you must study much ……

1 Like
6

Thank you everyone for the responses!
I’ll be pondering over all this info and most likely come up with more questions, potentially come up with next actions for me. Either way I’ll post back.
I do have other stuff going on so might be slow, but once I have things set up I will definitely post back my learnings, my thoughts anything else interesting along the way :slight_smile:

1 Like
7

In my opinion TRVs are too loud and not reliable enough.
Go for thermal actuators instead.
They run on mains and can just be plugged in to the outlet in case HA goes down.

8

If you plan to renovate the house, you could consider using floor heating instead of radiant heaters. This will also prepaire your installation for a heat-pump in future. To control floor heating thermal valves, I developed the ControlBox. It’s basically a Home Assistant server with hardware for heating control integrated. If you already have Home Assistant; there will be an ESPHome variant with wired ethernet as well.

1 Like
9

This topic is exploring thermostats on a similar system.