>>> Join Us in the Fight Against Air Pollution

AirGradient Forum

question about adding ERV

#1

I’m new to IAQ testing, and bought the I-9PSL-DE to test my indoor air to see if I really needed to buy an ERV. I had home energy audit that recommended the ERV as the house had a blower door test of 2 air changes per hour. I also have a whole-house air purification (MERV 16 filter) on forced air heating/cooling.
My readings over the past few weeks have been:
0 PM 2.5,
80 PM 0.3,
0 PM 1,
0 PM 10.
CO2 505,
TVOC (Ind30) 95
TVOC (Ind40) 101
NOx (Ind41) 1

Not having a baseline for “good air”, I put the monitor outside on a day with good air quality reports. The PM readings and TVOC readings went up substantially outdoors.
My uneducated eye doesn’t see any air quality problems with these readings, at least not enough to justify several thousand dollars to install an ERV.
I read through the long thread on TVOCs and set my VOC/NOx Index Learning Time Offset Duration to 720 hours. Am I safe to assume this device is adequate to measure air quality for the purpose of evaluating the need for ventilation? And are there other pollutants this doesn’t test for that might be a concern (I have a radon sensor and mitigation)?

#2

The CO2 is lower than I would have expected with a well sealed house. Now that your unit has been outside, the auto calibration should get updated, or you can set it outside again and then force a CO2 calibration to make sure.

I haven’t done a blower door test but have seen CO2 be steadily 1000-1500 in a home with 4 people and wondered about an ERV for that

#3

Yes, I think your values look excellent for indoor air quality.

What could be worth looking into are decay curves, e.g. after cooking how long it takes for the smoke from cooking to get flushed out.

#4

My C02 levels are fairly low because I’m the only one in the house, they do rise a bit when I’m in the room with the monitor. I think an ERV would drop your CO2 levels but so would opening a window. The home energy audit I had included the blower door test and a walk around the house with an infrared camera. It was very helpful and worth the $400, very reasonable if you ask me.

I’m very pleased with the Airgradient monitor, just wish more HVAC people were aware of these devices. Not one HVAC contractor, or even the person that did my home energy audit, mentioned an indoor air quality monitor. I didn’t even know such a thing existed until I started thinking about what pollutants might be in the air that would warrant an ERV.