I’m sure there would be other settings that could be changed on a Vaillant to temporarily prohibit both heating and DHW, but that Holiday Mode gotcha is definitely a good spot; thanks, @judith.

@ecoste i was reading the installation manual for my Cosy6 stored in manuals.lib last night. It warns not to set flow temp below 36C as it affects performance. 
Big Question is why in the settings part of the App they allow you to adjust it down to 30C, contradictory to the manual.

I've got mine set to 36C and getting COP of 4.59 last week. Don’t feel inclined to tinker with the setting to see if it lowers the COP, also would need to assess any changes made with the different weather each week, how many times the doors are opened (change of air volume), solar gain (lol its January)

An off-the-wall question; has anyone come across a relatively cheap smart light for outside with PoE connectivity? The only things I’ve found are ridiculously expensive and don’t look great. In fact, they’re costlier than PoE security cameras with lighting integrated, and all I want is the light bit.

I'm unsure what you're wanting by having a PoE connection @majordennisbloodnok 
Is that just a way of getting power to the outside light?

It's relatively easy to assemble your own smart-light, especially if you're a contributor to a Tinkerers' Corner. 😉 

The RCWL-0516 is a microwave presence detector which can be installed within any (non-metallic) external enclosure. It triggers an output if a human approaches within a range of around 5-8m.

There are a couple of pads on a corner of the PCB which allows you to add an LDR light-sensor. The presence detector output will then be prohibited from operation in daylight.

In the above example I've added an AT-Tiny-85 microcontroller and a 'logic-level' mosFET to control the brightness of the LED (porch) light, which is mounted separately.

My enclosure is 3D-printed, and includes a transparent window (arrowed) which allows in enough daylight to trigger the LDR.

In my case the method of operation is for the porch light to come on at 20% brightness at dusk.
If a human approaches, then it fades up to 70% within a second.

It will remain at that higher level for 1-minute after the microwave sensor is no longer being triggered, then fade down to 20% over 5 seconds.

Thanks, @transparent.

The reason I want PoE is twofold. Firstly, it’s a lot easier to run some cat6 cable than wire in a new mains socket, especially for more remote places. The second is that I don’t want motion detection so much as the ability to control it from Home Assistant, and I’d far prefer to do that over a wired connection than wifi.

I am starting to think I may need to do something DIY with an esp32 board and an RJ45 socket to build my own but if there’s something already available I’d love to see it.

Yes, I too use LAN cabling from a PoE router to supply power to remote places.
In my case that (Netgear) PoE Router is itself supplied with a nominal 50-52v DC from my LiFePO₄ storage battery  🙂 

Unlike you, I don't have Home Assistant, and I prefer each light to have integral autonomous control.
I don't like the thought of having a single point of failure which could lose control of everything at the same time.

Posted by: @transparent

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Yes, I too use LAN cabling from a PoE router to supply power to remote places.

I hear that can work very well. It is probably easier to keep secure than the average wifi repeater..

I use my Home assistant more like a lab, so will never be the most reliable. But when it comes operating smart plugs, using HA does not stop them from being operated via their own apps, so it is not difficult to make sure that it is not single point of failure (SPF) for those simpler routines.  

Since I try to prevent SPF, I end up with multiple points of control. And when some issue crops up, that can make it more difficult to troubleshoot. So no simple answer?

I have to admit that I generally underestimate the effort involved in keeping every bit updated and tuned to work as my needs change. 

@batpred, you’re quite right; it does work well. I don’t have any repeaters and I don’t have a mesh network. I do, of course, have wifi but that’s via physical access points cabled back to the central switch (and PoE over the same cable, meaning no need to compromise on siting just to be able to plug it in).

Anything I care about is wired so that the connection is as secure as it can be. You’re right that single points of failure exist, but in my case I’m comfortable the time to recover is an acceptable timeframe; it is, after all, only a domestic setting. You are also right that all my smart kit will continue operating with sensible defaults whilst uncontactable, and that is why I’d prefer a ready made solution for the PoE outside lighting. It’s only an extra to augment what we have already, though, so it’s not the end of the world if it became unavailable for a while.

One thing I have done to cope with the extra complexity of the installation I have is to install the BookStacks addon and create a home Wiki for documenting everything. The HA server is backed up regularly to the cloud, so a quick restore to another HA box would give me all my documentation immediately. And yes, I have tested it in practice. 🙂