Is There a Way To Control ERV/HRV Based on Air Staleness?

[DavidNJ]

In another thread there is a discussion of using CO2 levels to determine air change rates. Typically, CO2 is at 450ppm outside, but can get way over 1000ppm indoors.

While humidifiers and dehumidifiers can be controlled based on the humidity level, is there a way to control Energy Recovery Ventilators and Heat Recovery Ventilators based on an air staleness measurement such as CO2 level?

Presumably, that would require the control to monitor the CO2 level and turn on the ERV/HRV and signal the air handler to turn on the blower when needed even if heat or cooling weren't needed.

Does this exist? Does it exist with some other air staleness indicator?

[dan sw fl]

In another thread there is a discussion of using CO2 levels to determine air change rates. Typically, CO2 is at 450ppm outside, but can get way over 1000ppm indoors.

While humidifiers and dehumidifiers can be controlled based on the humidity level, is there a way to control Energy Recovery Ventilators and Heat Recovery Ventilators based on an air staleness measurement such as CO2 level?

Presumably, that would require the control to monitor the CO2 level and turn on the ERV/HRV and signal the air handler to turn on the blower when needed even if heat or cooling weren't needed.

Does this exist? Does it exist with some other air staleness indicator?

Do you have a modern air handler?
Check out all the options.

..............................
OR

On- off timer could be set-up to run blower 1/3 or 1/2 the time at slower speed.

http://www.fanhandler.com/

IAQ mode

[DavidNJ]

The key would be measuring some indicator of stale air such as CO2 level the way a humidifier runs off humidity level.

[dan sw fl]

The key would be measuring some indicator of stale air such as CO2 level the way a humidifier runs off humidity level.

What is the chemical composition of "stale" that YOU can define?

[dan sw fl]

I'll set you up with a Reliable instrument?!

Cost is $5,678 + tax

[DavidNJ]

Since CO2 meters of thermostat accuracy are under $200, you seem to have your decimal point off a bit!

[dan sw fl]

Since CO2 meters of thermostat accuracy are under $200, you seem to have your decimal point off a bit!

Not really, detecting STALE reliably is PRICE LESS

[dan sw fl]

http://www.raesystems.com/products/qrae-ii-pump

QTY 4 REQUIRED.
Datalogger, program, circuitry, set-up and testing.

$ 4, 876 discounted this week.

Re-shelving fee 35%.

Activates blower for 20 minutes, air sampling repeats 10 minute after shutdown.

[DavidNJ]

And that has to do with measuring CO2 as a Rolls Royce has to do with NYC taxi service. They are both cars with 4 wheels, and I imagine you can order the Rolls in yellow.

CO2 meters start under $200. Google it.

[Carnak]

20 years ago, van EE was selling a CO2 based controller for residential HRVs. I have a telaire ventostat myself

http://www.gesensing.com/products/te...nt.htm?bc=null

[Carnak]

looks like vanEE now offers a "Detector" controller. It seems to respond to aldheydes, alcohol, ketones, carbon monoxide.

If you hang out in this forum long enough you will notice people talking about renewing oxygen and purging pollutants. They will even post formaldahyde readings.

Now all these IAQ devices are not like a tricorder from Star Trek, and formaldahyde meters will false alarm and read high formaldahyde levels in the presence of alcohol, carbon monoxide etc.

So it looks like vanEE is capitalizing on how other 'bad indoor pollutants" will register as formaldahyde, so in this case two wrongs make a right, and it allows the control to turn on the ventialtion over a wide arrray of problems.

CO2 itself is not a pollutant, and those who go on about 'renewing oxygen' are full of it. CO2 does give an indication of the ventialtion rate and that is it. So something that responds to actual bad things in the air is actually responding to indoor pollutants or 'staleness'

[DavidNJ]

Thanks...they are all CO2 sensors (I found two other brands also using the info you provided as a basis) designed for demand controlled ventilation. Yes, CO2 is only monitoring the air change rate the number of occupants, but high levels have adverse effects. Many of the units have remote sensors with transmitters.

It is probably the right addition to an HRV to ensure it runs when needed and rests when it isn't.

[Shophound]

CO2 seems the way to go as it can account for variances in building occupancy loads. Why ventilate a house that is unoccupied (meaning no pets as well as people)?

Caveat is it must sample moving air to work. So even during unoccupied times it would need to run on a sample timed basis to determine if ventilation is required. You can have most of your cake, but not all of it.