Perhaps we could all agree with some proxy or working definition for stale vs fresh, but the word stale is ambiguous, and will mean different things to different people.
miner: stale = methane/low-oxygen
dry climate: stale = high particulates/CO2
humid climate: stale = humid AND high particulates/CO2

And while indoor air is usually more “stale” than outdoor air, that’s not always the case. Matt McLagan identified an issue where his intake is not noticeably fresher than his exhaust. More generally, some regions have days/times with low air quality, and sometimes doctors recommend staying indoors. On those days, the intake air would be more “stale” than the indoor air you’re exhausting.

I am a bit surprised that you did not exhaust from the laundry room which could be [not always] a source of high humidity [re: article: high humidity = source for bad stuff to grow].

While it takes very little energy, = 100 watt light bulb, to run the ERV have you calculated the COST of heating/cooling the ventilation air per year?

I, too, am in the Atlanta area, but Zehnder does NOT have a dealer in the area.
How are you going to commission the system when finished? And what should this cost be?

When I called Zehnder in NH, since they have no dealer in my area, their offer was “send us the money, trust us and good luck”

I have contacted Energy Vanguard to design my zoned, Water Furnace GSHP System.

No concerns about the EPP supply and exhaust pipes?

Btw, are you employing any make-up air strategies for the bath fans? Will the Zehnder ERV provide any?

And a followup to your last sentence, John, is that you need to specify what may seem like an oversized ERV to be able to run it at lower speed. At Energy Vanguard, we generally specify an ERV with twice the maximum air flow rate we want to run continuously. That also provides room to have boost mode with switches where the extract vents are.

I’m using a Lifebreath 170ERVD, which is not the premium product the Zehnder is.
I’d be curious if you notice anything similar when you put yours in commission.
I’d recommend keeping those outdoor hoods well-separated if you can.
And I’d recommend a CO2 monitor to measure the performance!

Hi Barry. I think it is worth noting that the vapor permeable material in an ERV core is less thermally conductive than an HRV core. Therefore, an ERV has a lower heat recovery efficiency than an HRV. But in a humid climate it makes sense to forfeit the highest heat recovery efficiency in order to reap the benefits of humidity transfer from the more humid airstream to the less humid airstream.

Also, lower fan speed = slower airflow = more time for heat/humidity recovery = higher efficiency. So, it makes sense to run an H/ERV at the lowest speed that provides acceptable indoor air quality.

My own experience with the 4 HRVs I installed over 20 years in my 4 of my own houses is that they they are magical. I have been told that ERVs are even more so. I do not want to skew your scientific judgement, so pay no attention to my empirical assessment and give us the numbers as you gather them. Should be very interesting.

Yes …. and Thank you.

Barry: Great question. The capillary core consists of a lot of parallel channels separated by a thin membrane. In a heat recovery ventilator, the membranes are vapor impermeable so only heat transfers through. In an energy recovery ventilator, the membranes are made of a vapor permeable material that allows water vapor to move from the more humid side to the drier side.

Make sense?