Controlling ventillation system?

[Andras Gaal]

Hi,

I would like to implement a ventillation system and am thinking about controlling it through Loxone. What are your experiences with controlling such systems? Is it a better practice to leave the control to the ventillation system or can I use my existing sensors (temperature / humidity) and look for some system Loxone can easily communicate with?

[Duncan]

many of the standalone systems have relatively poor control/settings and there is a good opportunity to add better control using loxone

i found that most underspecced the fans to offer a cheap quote, but the fans are running at a high% of max to give the required air changes leading to a noisy system

many only had a normal and boost rather than a finer control such as 0-10v, and many have a self-contained automatic summer changeover that removes the heat exchanger at a certain outside temperature but you cant override it.

i struggled to find a system with a 0-10v speed control and manual electric control of summer/winter but they can be found.

I used regavent who offered to provide both 0-10v fan controls for both the inlet and extraction fans, and also a 240v switched heat exchanger allowing full integration with loxone.

having loxone control things enables you to add other functionality such as c02 levels, humidity control, integration with blinds, heat exchanger control and motorised roof blinds to help with summer temperatures etc

you may well find that the required ventilation for building regs set by the ventilation company is far higher than you actually need, and being able to slow the fans from loxone saves energy and noise without compromising the air quality. I set my system and balanced the air outlets to meet buiding regs at around 40% fan speed, then run it higher (55%) in the mornings after the showers have been on, but only 15% at night for a silent system. It runs a boost of 70% for kitchen extraction or overheat extraction (with the heat exchanger switched out).

[Andras Gaal]

Thanks Duncan. I now have talked to a few companies, lot of them started talking in-room controllers for 100-200-300€ a piece. It more and more confirms my suspicion that these companies make big bucks on the control while the air handling is essentially very similar amongst them.

[Rob_in]

Hi,

We chose a 'dumb' system specifically because we have Loxone and intended to perform any control through that. It was quite tricky to find something affordable that could be interfaced with Loxone but ended up with a S&P (Unelvent) Domeo 210. They do larger models if your house isn't as small as ours.

https://www.solerpalau.com/en-en/heat-recovery-units-domeo-1942-serie/

Comms are via Modus and this seemed a bit temperamental to begin but think that was a wiring issue as now works fine. Fortunately you can change the address and other settings of the device to suit your Modbus implementation.

We have numerous points of control:

- Scaler block which sets demand according to humidity.

- Scaler block which sets demand according to air quality (we have $5 homemade MQ135 AQ sensors in a couple of rooms - works well).

- Demand boost on a timer when someone is in the WC (PIR sensor).

- Demand boost on a timer when someone takes a shower (detected by sudden jump in bathroom humidity but it has been suggested to put temperature sensor on the hot water shower manifold to detect flow there).

- Demand boost when the kitchen hood is on (we have a recirculator as the house is airtight). Ikea model I hacked to put a relay inside so Loxone knows when it's fan is running.

- Put the unit on bypass (fresh air directly into the house avoiding the heat exchanger) if temperatures in/out warrant this. Mainly for summer nights to bring in colder air if the house has become a little warm in the day. It's a bit more noisy in bypass but if we are away from home have it run full bore as who cares how noisy it is when we're away ;)

- Change the airflow balance and reduce flow if a window is open somewhere.

Think that's about it.

The manufacturer sells flow restricting vents (BM2D range aimed at commercial buildings) and I would like to fit these to the extraction rooms. They are 70EUR a pop though (plus the hassle of wires and more actuators) and right now seems like a convenience we don't need. The idea is that if you restrict flow to just the room that needs demand (taking a shower for example) then the overall flow rate can be lower as the other rooms would be 'closed' and not much airflow would happen there. Maybe will add these when we fit out our attic (further bedrooms and bathroom).

HTH.

Robin

[David Wallis]

Following with interest as looking at trying to see if we can follow the passivehaus best practices for a our refurb and considering HVAR systems - depending on what I can do for duct runs once the desing is done as the plant room may end up being 20m away from the furthest point and at one end of the house unfortunatley. 

[seniab]

Have been watching this group for a while as seriously considering loxone for my own build and plenty of questions to come, however, I’m a Passivhaus and refurb expert and sit on the uk technical group amongst other things so if I can help on anything with mvhr (or something else) just ask. I have so far found a few certified units that can be directly controlled by loxone through one of the extensions such as Zehnder or proxxon (HPV in UK), although I expect many more can be controlled through modbus.

As mentioned above you are likely to get better control through integrating with loxone but the gains will be marginal financially when it has been designed, installed and commissioned correctly, and this has repeatedly proven to be very rare. It could help with avoiding over ventilation in the winter and potentially create a more comfortable environment then but considering running costs for these units often come under £50 for the year the benefits of integration are minimal.

[Andrew B]

I control my UltimateAir unit (North America) from my Loxone and it works very well. Monitors humidity and allows for smartphone based speed control and timed boost requests (the latter also available via wall switches).

[Andras]

Speaking of control, is it a good idea to do room-by-room control of airflow (most probably through 0-10V vents)? Most systems I have found are either not controllable this way (so not preferred by for my use) or can accept one demand signal (0-10v) and increase/decrease airflow proportionally. The more I think about it, the more I think the global control of the system would suit my needs (low speed at night, quick ventillation when we leave).

Is there any added benefit in making the inlet/extraction fans 0-10v controllable? If yes, how do you control fans in the central unit?

[Andrew Brownsword]

In my setup the HRV (actually its an ERV) has an optional component I have that samples air pressure inside and outside (somewhere sheltered from wind), and it uses that to balance the intake / exhaust flows dynamically.  This is useful in a very airtight house (mine is built to the Passive House standard, albeit not certified).

Personally, I wouldn’t bother with room-by-room unless you have a really enormous house.  Too much complexity for the benefit you’re likely to see up to at least 5000 sqft, I’d guess.  Monitoring for occupancy would reap much higher benefits (turn off ventilation at least intermittently while unoccupied reduces heat loss via exhaust air, even with the HRV’s heat exchanger plus eliminates the power draw of the HRV).  Adding CO and CO2 sensors in addition to humidity is on my todo list as well, especially if you have any combustion appliances.

Also on the subject of ventilation:  for your cooking surface you need a hood fan, and it ought to be vented to the outside (even if not combustion I’d recommend that).  If you have a tight house, you really need to have a make up air duct that opens when the high powered exhausts turn on.  The HRV can only compensate for up to about 60 cfm (typically) of flow, so above that you need to let air in to make up for the powerful exhaust fan depressurizing the house.  The latter effect is unpleasant, and you’ll also find your exhaust fan doing much less than rated capacity!  In my place the home automation isn’t involved in opening the make up air (MUA) duct, it is just hard wired to the hood fan and dryer (both of which have very slightly spring loaded flaps to prevent airflow when the fans aren’t operating, but which don’t impede the exhaust).

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[Andras]

Thanks Andrew, good hint on the occupancy sensor automation.

[Jedi Tek'Unum]

Just built a home in Minnesota. Building codes here require a passive makeup air intake. Hoods are limited to 300CFM if you aren't doing an active (powered) MUA. In our climate, an active MUA means a massive/expensive electric heater that warms the incoming air. This morning our air temperature is -33F thanks to the polar vortex - I don't even want to think about what an active MUA, even with a heater, would feel like!

Fortunately, a hood above 300CFM is really only needed with a gas range/cooktop. Although the wife initially wanted gas I ended up vetoing it due to the expense of the MUA. Instead we went with induction (which she loves). Many hoods these days are rated above 300CFM and then have a way to permanently (well, I imagine that isn't really too permanent) disabled speeds above 300; in our case only the first 3 of the speeds do anything and the last 2 speeds don't go faster.

For ERV I have a Broan ERV140TE. I reversed engineered this model in my old house. The speed can be controlled via a resistor as described here. At the old house the automation was Indigo running on a Mac and it watched the CO2 level reported by Netatmo to adjust the ERV speed and time.

The standard HRV/ERV controllers are just plain stupid. Either on, full speed all the time, or on full 20 minutes per hour. In my opinion even 20 minutes per hour is way too much. And running at high speed in winter in Minnesota is just plain ridiculous. I found that 10-15 minutes every two hours on slow speed was enough to keep my CO2 levels good. In the summer it needed high speed. I haven't automated it in my new home yet so its grinding away 20 minutes an hour at full speed when its -33F outside! Not good. Its doing lots of defrosting I imagine.

I should warn that my research suggested that there is a lot of variation amongst HRV/ERV brands as far as how they are controlled. Many are rebranded Venmar but they seem to alter the resistor values for different brands just to keep life interesting. I found my values by measuring the cheapest controller they sell. I suppose there are also brands that don't use resistance values to adjust speed.

[Simon Still]

On Monday, 28 January 2019 18:00:04 UTC, Andras wrote:

Hi,

I would like to implement a ventillation system and am thinking about controlling it through Loxone. What are your experiences with controlling such systems? Is it a better practice to leave the control to the ventillation system or can I use my existing sensors (temperature / humidity) and look for some system Loxone can easily communicate with?

As others have mentioned, I'm of the view that you can overcomplicate this - i'm not sure what having continually variable fan speeds gains.   

I've got a Vent Axia Sentinal Kinetic which i've linked to Loxone.  It has volt free contacts for fans off (linked to smoke alarms), low (house unoccupied/overnight), and boost (when high humidity detected in bathrooms, toilet is used for longer than 3 minutes, or when cooker hood is running).  

I've got Loxone humidity sensors in the bathrooms but there is also an internal humidity sensor in the unit itself - i saw no reason to attempt to diable that.  Also, the summer bypass - the settings on the unit seem to work so no need for a link to Loxone that I could see. 

I'm not sure what finer control would offer - if humidity is high, or you're cooking you want to vent as quickly as possible then drop back to normal.  

Cooker hoods are an issue in an airtight/passive house.  You don't really want to extract a lot of hot air and put it outside, and draw in cold air that's not been through a heat exchanger.  

I've fitted a Berbel hood - they use a dyson style cyclone to extract grease (rather than just a mesh filter) and have a large, long life, carbon filter if used in reciculating mode (supposedly need to replace the loose carbon in the container about once every 3 years).  They do make an airtight vent for extract for airtightness but I just use the volt free contact to set the MVHR to boost when it's on.  It works well to both filter grease and smoke and remove smells.   

 

[Rob_in]

On Thursday, 14 February 2019 19:16:21 UTC+1, Simon Still wrote:

As others have mentioned, I'm of the view that you can overcomplicate this - i'm not sure what having continually variable fan speeds gains.

All you need for continuously variable fan speeds is a scaler block and a min/max limiter behind it if you want to keep the output within a certain range. It's hardly overly complicated.

As I said above, we use this for demand based on both humidity and air quality and it works really well.

The advantage is the ventilation is always working 'just enough'. Ie. it is never over speed and therefore more efficient. If you have the sensors anyway then why not? It's just a few more blocks.

Yes, there are scenarios you want to vent quickly (we use full boost when people shower or someone is cooking) but the scaler is great for the rest of the time. Particularly useful when guests visit and there's just a little more more CO2/humidity in the house than normal for example.

Robin