Back Pressure Logic
Hello, I'm using 1-3 flair vents in each of my 11 rooms, coupled with an Ecobee thermostat and sensors, which are used to set temp and the occupancy of these rooms. I have correctly set the number of vents in my system to match my HVAC capability and I see vents are being kept open for back pressure reasons as expected. However, there are a couple of problems with the back pressure logic as I see it:
1) If a room is already within the desired temp range and back pressure protection is in effect, that room should not be heated/cooled IF there are other rooms (active or not) that would benefit from cooling/heating to bring them into range. See my screen shots below - the powder room is well below target temp while the dining room & kitchen are above, yet powder room is open while the other rooms have closed vents.
2) If the logic in point 1 is applied, when a room has partially open vents due to back pressure protection, the room should have ALL its vents open. In the example I gave, the kitchen would benefit from the additional cooling and yet is only being partially cooled.
Even though these rooms are inactive, why waste the cooling/heating capacity of the system on rooms that won't benefit, as I'm going to use these other rooms at some point, so use the energy to prep those rooms for usage later?
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Excellent question. I also have had similar situations that I have noticed that don't make sense to my limited understanding of the logic. It would be great if someone from Flair could shed some light on the logic for this situation. I haven't seen much exposition on the logic from them in the past. (perhaps they consider it proprietary?). I appreciate your screenshots especially. In my setup, I have never seen "Back Pressure Protect is active", probably because only about half of my vents are Flair, so there are enough open vents that aren't flair to alleviate any back pressure issues.
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Hi Oliver McGill and Chuck Askew,
We have two Back Pressure Protection Algorithms to choose from
Active Room Priority
Flair will prioritize keeping Vents closed in Active rooms and open Vents in Inactive rooms first for BPP.
Inactive Room Priority
Flair will prioritize keeping Vents closed in Inactive rooms and open Vents in Active rooms first for BPP.
If this leaves either of you with further questions please let me know. If you have specific examples where this isn't working as you expect please write in with specifics to our support team - support@flair.co
Regards,
The Flair Team
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Where do I set this priority? And if it's set to "inactive room priority" and all vents are already open in active rooms, during BPP will it prioritize the inactive rooms that need cooling/heating the most? I.e. from my example, will it still try and cool the powder room even though there are other rooms that would benefit more.
This conversation is of a benefit to your users, taking the conversation to email removes that visibility and is also not useful for potential customers who want to know what is actually possible with your products. Let's keep things public please.
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Hi Oliver McGill and Evan Adams,
The setting for Backpressure Room Priority can be changed by members of Flair's Support Team. If you'd like yours changed, please send an email to support@flair.co.
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BWR - Flair Why isn't that just a setting in the app?
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Hi Todd Stotesberry,
This is one of the features that we like to have a dialogue with the customer about before changing and at this point we have not made it a feature the user can change in the app. I would be happy to submit a feature request to expose the Back Pressure Priority setting, but when or if this is released will be decided by our management team.
Regards,
The Flair Team
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Been thinking about this a lot. Seems to me this is because BPP exists to make sure you don't over pressure your supply ducts and damage your system. It assumes any & all non-flair vents could be closed. So all I had to do was tell flair there were more vents in my system than I have and the BPP doesn't kick in because the % of flair vents is so low vs whole system.
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@Evan Adams. Interesting take. I have assumed that the Flair BPP algorithm assumes all non -flair vents are open. I don't know that is the case, I just assumed it. I wonder if the flair team can be shed light on this. Either way, you can manipulate it by playing with the total number of vents you input into the of app
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Hi Evan Adams and Chuck Askew,
The Flair Back Pressure Protection algorithms are in place to protect your HVAC equipment. As more and more of the vents in a ducted system close the static pressure increases. When the static pressures get too high it can damage your HVAC equipment and the ducting. We do not recommend that you play with the total vent count to get around these protections unless an HVAC professional reviews your system and says it is safe, likely due to the presence of a bypass damper that can bleed the excess pressure from the supply side of your system back to the return side.
Flair assumes that your old-school vents are open and that the only vents opening and closing in your system will be the Flair Smart Vents. If you keep certain old school vents closed at times this should be accounted for in the total vent count you specify in the thermostat settings.
Regards,
The Flair Team
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