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With elevated levels of formaldehyde in my home air, should I install an ERV or HRV system?

I just tested the air quality in my home and found it to have elevated levels of formaldehyde.

We researched and found among other things (lowering the humidity, getting clean air plants in the home, air purifiers, getting rid of the formaldehyde containing furniture), installing a system to push fresh air into the home would help to lower or get rid of the formaldehyde.

(I live in Chicago, IL in a home that was built in the late 50's)

They will all be using the existing duct work and there is minimal space to install the machine.

The 3 quotes were:
1. New Life Breath ERV system, around 100 cfm ($3,146)
2. Carrier Comfort Series ERV, 100 cfm ($4,195)
3. Bryant ERV XXNNA090, 90-130 cfm ($3,160)

I received these 3 quotes above. Is the ERV the best option for my house and for eliminating the formaldehyde, or would an HRV be better? Also, are each different companies ERV's and HRV's relatively the same quality?

Thanks in advance for your help!!!

Best,

Jeremy

Asked by Jeremy Stern
Posted Nov 1, 2016 10:26 AM ET

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17 Answers

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1.

Formaldehyde will not be exchanged through an ERV's core. Both an ERV and HRV will have the same effect on the formaldehyde level at any given ventilation rate.

Answered by Dana Dorsett
Posted Nov 1, 2016 11:01 AM ET

2.

How many square feet is your home? How many occupants? Can you share your formaldehyde test results?

Also... It's curious that any older home has high formaldehyde readings. Have your remodeled recently or purchased new furniture?

Answered by Steve Knapp CZ 3A Georgia
Posted Nov 1, 2016 11:09 AM ET

3.

Either HRV or ERV will work to reduce formaldehyde levels. There's some data showing that with some ERVs, the rate of formaldehyde removal is somewhat lower than with HRVs, but that data is for the type of ERV used in large commercial buildings, with large desiccant wheels, not for the layered paper type used in most or all small residential ones like what you are looking at. It seems likely that the residential types of ERVs are not significantly different from HRVs at removing formaldehyde, but I don't know of any data on that. Dana seems more confident of it.

So I would choose between HRV vs. ERV based on other considerations. In your climate you could argue for going either way, assuming you air condition in the summer. If you don't air condition in the summer, I would choose an HRV.

Installing an HRV or ERV using shared ductwork with an HVAC system is generally problematic. I would choose a system with a minimal but independent distribution system over a system with shared ductwork.

As far as choosing between those three, I usually recommend looking for a unit with an "ECM" motor which uses substantially less electricity. Since that motor will run all the time, it's a situation in which is can be worth investing in a more efficient motor. Life Breath has an ECM model, but only in HRV, not ERV, it seems. There are other manufacturers who make ECM ERVs, including Venmar, Zehnder, and vanEE.

Answered by Charlie Sullivan
Posted Nov 1, 2016 11:28 AM ET

4.

Dana stated categorically that "Formaldehyde will not be exchanged through an ERV's core."

The truth is more nuanced.

Here is a link to the Max Sherman article that ignited the controversy: ERVs Get The Yellow Flag.

Here is a link to a previous GBA thread on the issue: Does using an ERV as opposed to an HRV pose any risk that air-borne contaminants may fail to be fully exhausted?

Here is a link to Home Energy's followup article on the controversy: ERVs Still Get The Yellow Flag?

Answered by Martin Holladay
Posted Nov 1, 2016 11:29 AM ET

5.

Square feet: 1374
2 adults and 3 young children
Our formaldehyde results were:
Formaldehyde concentration: 81 ng/L (65 pub)
We were considered at the upper end of the "elevated" level according to Indoor Science in Chicago.
(they conducted a 20 minute test using an active sorbent tube with analysis using the Hantzsch method of Prism Analytical Technologies, Inc.

We did update the house with many new things, a re-finished basement, carpeting, a few new furniture pieces, a new kitchen from Ikea....

Overall we're still not so sure about why it's so high, and why things haven't off gassed more, b/c most of our new construction happened 3 years ago when we moved in.....

Answered by Jeremy Stern
Posted Nov 1, 2016 12:17 PM ET

6.

From the "ERVs Still Get The Yellow Flag" article:

----------------------------

Results

We measured formaldehyde transfer of only 0.9% in high speed (0.9% returned into the house versus 99.1% exhausted to outside). We also validated the SF6 gas transfer on the same ERV and obtained exactly the HVI-published EATR of 1.9%.

------------------------

OK, so it only fixes 98.% to 99.1 % of the problem, in a properly balanced ERV system, to maybe only 75% if it's badly unbalanced and the incoming air temperature is low.

Answered by Dana Dorsett
Posted Nov 1, 2016 12:26 PM ET

7.

Thanks for all of the responses so far.....the articles and previous threads are helpful and just to verbalize where I'm at....

I'm a bit more confused now than I was before I asked my question.

I am hearing that there is some controversy on the ERV's....then is an HRV the better and safer option?

Answered by Jeremy Stern
Posted Nov 1, 2016 12:50 PM ET

8.

If you have natural gas burning appliances, check to ensure you have adequate ventilation. Commercial styles ranges can generate a lot of combustion gas, for example. It also helps to keep humidity below 50 percent since more humid air seems to increase formaldehyde emissions.

If you haven't already, download this formaldehyde update from the Consumer Products Safety Commission: https://www.cpsc.gov/PageFiles/121919/AN%20UPDATE%20ON%20FORMALDEHYDE%20...

Answered by Steve Knapp CZ 3A Georgia
Posted Nov 1, 2016 1:15 PM ET

9.

Jeremy,
I agree with Dana that either an ERV or HRV will work. For more information, see HRV or ERV?

Answered by Martin Holladay
Posted Nov 1, 2016 1:26 PM ET

10.

Q: I am hearing that there is some controversy on the ERV's....then is an HRV the better and safer option?

My answer: It's true that there's a little controversy about exactly how well ERVs reduce formaldehyde. But there's no controversy about whether they work. And even with a pessimistic assessment of how well they work, you could get more formaldehyde reduction with 100 CFM from an ERV than you would from a 90 CFM HRV.

So my recommendation is still to choose based on the other considerations, as discussed in the article Martin just linked to. If we have made you nervous about whether an ERV will work well enough, we should apologize, because it will be fine--we are mostly geeking out over the details for our own amusement, but we all (I think) agree that ERV will be fine. If that isn't convincing, you could simply bump your CFM to 110 instead of 100.

Answered by Charlie Sullivan
Posted Nov 1, 2016 3:35 PM ET

11.

An ERV might have a secondary benefit relative to an HRV of making it easier to keep the humidity low in the summer.

There are a couple benefits of dedicated ductwork: i) You have control of where the stale air is drawn from. To take advantage of this benefit, you would need to have a better idea of what is causing the high formaldehyde. ii) You don't need to run the furnace fan whenever the ERV/HRV is running.

Answered by Reid Baldwin
Posted Nov 1, 2016 4:00 PM ET

12.

For a given amount of injected latent load in the summer season you can run an ERV at a higher ventilation rate, which is an important consideration if you're holding the line at 50% relative humidity, but far less so if you'll tolerate 60% relative humidity:

The dew point of 50% RH / 75F air is about 55F, whereas the dew point of 60%RH/ 75F air is 60F.

In Chicago the average outdoor dew point is above 55F from the beginning of June through half-past September, more than 3 months where high ventilation rates would be a latent-load adder, and an ERV might make some sense.

But the average outdoor dew points in Chicago average above 60F for about the 7 weeks from the beginning of July through the third week of August, and an HRV is probably going to be fine, since that's when the AC is running a higher duty cycle anyway, and it's only ~7 weeks of additional latent load.

Keeping it at 50% or lower in summer is usually only an issue for those allergic to dust mites. Most people's health & comfort are not adversely affected by 60% relative humidity.

For typical season outdoor dew points in Chicago, see the dew point graph near the bottom of this page:

https://weatherspark.com/averages/31158/Chicago-Illinois-United-States

Answered by Dana Dorsett
Posted Nov 1, 2016 4:36 PM ET

13.

Thanks so much everyone. I really appreciate your input.

I am taking everything into consideration.

Just regarding buying an individual ERV to get rid of formaldehyde, would there be a small or big difference between models?

For instance, I was just given a quote for the CARRIER ERV model ERVXXNVA1090. Or I'm also waiting on a quote from a Zehnder supplier (I understand that Zehnder is a bit higher quality)

Should I be picky in what i install, or no? If they are all going to do a relatively similar job to get rid of my formaldehyde then I'd be more inclined to just get something installed asap.....

Answered by Jeremy Stern
Posted Nov 2, 2016 1:44 PM ET

14.

Also, regarding dedicated ductwork, is this something I should really do to maximize the efficiency of the ERV? Could I get away with not installing it? Each of my 3 quotes were not planning on doing this...

I'm asking this b/c it's a much bigger project to install all new ductwork for the machine... :(

Answered by Jeremy Stern
Posted Nov 2, 2016 1:47 PM ET

15.

Jeremy,
Here is a link to an article that discusses the pluses and minuses of different approaches to ducting HRVs and ERVs: Ducting HRVs and ERVs.

Answered by Martin Holladay
Posted Nov 2, 2016 1:59 PM ET

16.

A system with dedicated ductwork, at least for the outgoing air, will do a better job of removing the formaldehyde IF you identify the source and design the system to extract from near that source. Otherwise, the difference is primarily energy impact, including: i) direct electricity use for the fan, ii) increased heating and cooling load, and iii) increased operation of your furnace fan if necessary.

Answered by Reid Baldwin
Posted Nov 2, 2016 2:29 PM ET

17.

Would be useful if you bought a formaldehyde monitor and could figure out what exactly is causing the elevated level. Might be much more effective to remove one or two things vs trying to ventilate it away.

Answered by Jon R
Posted Nov 2, 2016 8:08 PM ET

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