[pzduniak]

>that they are very expensive niche products

My entire "medium sized European suburban house" runs on a $2.5k 400m3/h unit with HEPA filters made in Lithuania - and that was the more expensive model that I can directly control over MODBUS / 0-10V signal (even turning it into a "dumb" unit). Most of the expenses were running the ducts. YMMV

It's just awesome. Every single room has fresh-smelling air and after fine tuning all my heating systems with algos implemented in Home Assistant - I'm getting ~60-100ppm over outdoor CO2, perfectly clean air, temperature within 1C of the set value, on-demand humidity extraction after showers etc. All it needs to be properly overengineered now is a bunch of dampers and per-room CO2/humidity feedback :)

[tomashubelbauer]

I wish this was as common as having a fridge in the house. The productivity gains from people not being sleepy and tired from shit air would be insane.

[tashoecraft]

When having my mini splits installed I pushed for an erv system in the bedroom. The installer had only ever done them in commercial units, and he hemmed and hawed about it, but I had two c02 monitors in my room showing it getting to above 2000 whilst sleeping. I've noticed a big improvement in how groggy I feel in the morning.

[BizarroLand]

If there were good enough ERVs that could be installed by the DIY'er for about the cost of a cheap refrigerator (~$600 or so) then they would be more common.

I get that manufacturing the transfer plates isn't simple or cheap, but other than that one thing they're basically fans, they shouldn't cost that much.

[michaelmior]

> after fine tuning all my heating systems with algos implemented in Home Assistant

I'd be very interested in hearing the details of this.

[pzduniak]

I'll definitely prepare a longer write-up when I have everything figure out, but here's a summary:

I have 4 systems:

- Komfovent HRV for ventilation

- NIBE F-series heat pump for floor and water heating

- Vaillant gas boiler that "supports" the heat pump

- Samsung multi-split AC units

HRV - Komfovent uses the same controllers in all of their units, so you get all the communication goodies you'd want - though it took me a long while to figure out that basic features need to be toggled on :) There are existing YAML presets for their C6/C6M controllers on HA forums. The only caveat is that if you want to feed it a virtual thermostat, you need a stuff a device simulating a 10k NTC inside of the ventilator. Otherwise it's just a single Ethernet cable.

Heat pump - I'm not exactly sure if I'm happy with NIBE, but thanks to the community the integration ended up being quite easy. I wasted a bunch of money on their MODBUS40 just to learn that you need to use a certain MODBUS address in the internal bus to make certain registries writeable (eg. thermostat values) - so I took an ESP32 with Ethernet, a galvanically isolated RS485 dongle, a 12V to 5V converter and used https://github.com/elupus/esphome-nibe. The firmware extracts my templated HA sensor's value and feeds it to the heat pump as a virtual thermostat.

Vaillant uses this weird "eBUS" protocol, there's a bunch of cheap PCBs that you can use to connect to it - I'm using https://github.com/danielkucera/esp-arduino-ebus. That's the last system that I haven't touched :)

Samsung ACs use their MIM-B19N modules installed in the outdoor units. There's some magic around enabling remote control, but once you plug their diagnostics device into their indoor units, you can flash all of them at once. I had to mess around with internal NASA addresses to have all the units appear at once.

For indoor sensors I have 3 types:

- AirGradient units measure CO2, tempeature, humidity, PMx etc. - these are mounted at ~150cm and feed the "current house temperature" template.

- I have like 8 Everything Presence One devices, powered by a custom PCB that converts 12V/24V sent over wired alarm cables to the device. They have built-in temperature, humidity and motion sensors. These are mostly installed for motion sensing and their height makes the temperature measurements quite useless.

- Everything else (and most importantly bathrooms) is done using custom ESP32-C3 devices that use SHT31 sensors to measure humidity and LD2412 for movement sensing. Also using the same adapter PCB for powering.

Thermostats are synchronized across all the devices with HA scripts. The HRV specifically uses its own wired temperature sensor to determine if it should enable heat recovery ("free cooling mode"), since its extracted air temp is always a bit lower than room temp (laziness :-)). "Current temperature" template fed to other heaters is derived from multiple room temperatures (currently using an average), with rooms "ignored" if AC is heating there (or was turned on recently). Ventilation has 2 modes set up - 20% and 80% - with the latter toggled by a bathroom humidity threshold.

There are 3 remaining things I want to set up:

- auto switching to gas heating if it's cheaper / the house is running on batteries - so far I've only imported electricity / gas prices into HA and quickly realized that I'm missing a power monitor on the heat pump circuit

- dampening of air ducts to reduce the temp drop when high humidity extraction boost gets triggered

- using more of the HRV range by auto-adjusting fan speed depending on real CO2 values - there's max 2 ppl at the house most of the time, so even at 20% the HRV is quite wasteful

[michaelmior]

Very cool! I think one of my biggest things is that I need my sensors to be able to manage things well.

[semi-extrinsic]

As a comparison for a "dumb" system, our house has a Nibe F110 that handles all air extraction and energy recovery (only for water heating) and a single Mitsubishi mini-split AC. And the bedrooms have some small electric panel heaters. I just cannot be bothered to fiddle with the smart house stuff, this solution works just fine for us.

[karussell]

How is the noise of these systems? And how often/long need they run to give you clean air and humidity extraction. Is there extra noise when it is windy outside? Is it installed inside the windows somehow or do I need to drill through the wall?

[sgerenser]

Typically 2 holes, one for air intake and one for air outtake are drilled through the wall. They’re often installed when a home is being built or heavily remodeled. They can be installed after the fact (especially if you have an accessible basement or attic) but it might be a bit invasive running ducts where you need them.

[ericd]

Alternatively, we got one piped into the HVAC ductwork. It's not as optimal as its own ducting, but it's much easier/cheaper than running a bunch of new ductwork.

[organsnyder]

That's what we did. Our house was built in 1916, but the weather sealing we've done combined with six people breathing in it led to quite high CO2 levels. We have a traditional ducted air conditioning system in the attic (heat is hot water radiant), and added the ERV there. It made a massive difference.

[ericd]

Yeah, same here on most counts, even going down to 3 ACH on the blower door test made CO2 levels pretty high, now they’re barely above outdoor.

[danans]

> My entire "medium sized European suburban house" runs on a $2.5k 400m3/h unit with HEPA filters made in Lithuania - and that was the more expensive model

That is just the HRV, not the design of the system, the ductwork, and the installation. All those add up. In new construction those costs can be shared with the regular HVAC system design, but in a retrofit its far more expensive

[tinco]

Anyone know if there's a good way to control 0-10V dampers? I looked for a solution to control 5 dampers but I didn't find anything, so I started to design my own a couple years ago but never finished the project. I'm having a hard time imagining something so common doesn't have a common solution.

[pzduniak]

If you're OK with large controllers, the cheap Chinese RS485 stuff seems to work perfectly fine. For "digital inputs" I started out with Polish $150 devices, eventually ended up using the cheapest AliExpress listings for some expansions and so far they've been working exactly the same, with the only difference being the quality of the docs. I'd expect the 0-10V modules to be exactly the same.

[yrcyrc]

Would you have a link/reference?

[pzduniak]

https://www.komfovent.com/en/products/domekt-r-400-f-c6m-573

I think this is the one I'm using for ~200-ish sqm.

[yrcyrc]

Great thank you