Regular Guest
House is 3 years old. When I put the airadvice outside, the VOC levels are really low (almost non detectable). I agree, the offgassing in a new house is always there - BUT, why would the offgassing be worse in the winter than in the summer - also why do we get big spikes in the VOC levels? It would seem if materials were offgassing, it would be more of a constant, high level, rather than all of these fluctuations we are seeing.Originally Posted by l'ville guy
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Do you open your windows in the summer? During the winter is when you button your house up the tightest. Probably why it is trapping more VOC's in the winter. Also people tend to go in and out more often in the fairer weather, creating more and more air exchanges.
We only want to do it, if we can do it right.
Banned
#13 01-03-2008, 07:07 PM
tfwalsh
Regular Member Join Date: Jan 2008
Posts: 8
"The negative pressure idea is very interesting. It would explain why things are worse in the winter. If this is the problem, is there a way to fix it? If it is sewer gas, how can we stop it from coming in? We already have a Lennox Heat-recovery ventilator installed, and I thought that was supposed to create a positive pressure in the house."
If they actually balanced the air flow for the HRV,yes positive,if not could be negative.
Regular Guest
Most of the time in the summer we kept the windows closed, except for running a test to see what effect open windows would have on the airadvice. Sure enough, when we opened all the windows, the VOC readings plummetted. When the windows were closed, the VOC levels went up, but not nearly as high as they are now in the winter. Also, there were never any spikes in VOC readings inthe summer, like we now have in the winter. That's why I've been suspecting tha my heater might be giving something off...
Banned
What controls the HRV run tims,and did they balance the air flow ,so as to not create negative pressure.We have found several that were not balanced by others,just ducted .
Where does the HRV connect ,to the ducts,for fresh and exhaust air?
Professional Member
tfw
For some reason your house is in negative pressure. I would agree with Dash that the HRV needs to be checked to make sure that this is not causing the problem. My guess is that it probably is.
Differences in pressure create a very powerful force. It is not uncommon to have VOC's from a water heater or other gas operated device drawn into a space with negative pressure. Also VOC's such as paints stored in a garage could be drawn into your living space. Just because you are not seeing high VOC's on the Air Advice in the garage does not mean this is not happening.
The fact that you do not have high VOC's when you are opening doors and windows supports this conclusion. Anytime you open up the house (by opening windows or doors) to the outdoors you stabilize pressure and your VOC's go down. Conversely, your highest VOC readings are at night - when the house is probably in the highest negative pressure.
Get your HRV checked and balanced.
Regular Guest
Again check the co2! This will tell you how much outside air you are getting!
Regular Guest
A three year old house is pretty new. New homes are built tighter than ye' old days. Newer homes are built with composite materials such as particle board that emit VOCs, and larger amounts when the material is humid. When you come home after being away for a few days do you get hit with that "new house" smell? This would be the off-gassing construction materials including kitchen cupboards, flooring material, carpets, furniture etc.
The HRV was a good addition. By constantly bringing in fresh air it will dilute the pollutants. However if the HRV (or your furnace) return air is routed using floor joists as make-shift plenums, again constructed of off-gassing construction materials, you may be distributing more VOCs and that may explain the spikes, coincident with the furnace fan cycling.
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Clothes drier, kitchen hood, bathfans, and stack effect cause negative pressure at the lowest levels in the home. Wind is the biggest negative pressure generator. HRVs are balanced flow devices at best. Most are installed poorly. Balancing the in/out flow and distribution are issues most contractors do not deal with.
The most effective ventilation is make-up air distributed low in the structure. Most air leaves your home high in the structure and down wind. The idea of low water in traps, marginal vent stacks, and burping when flushing toilets also allows soil gases to enter the home. Keep in mind stack effect is at it's high middle of the night.
More make-up air ventilation and tape the drains that are not used regularly. Maybe block the inlet of HRV and operate the make-up air on high speed. High vocs should be able to be identified with air sampling by a good industrial hygienest. If high vocs are and occasional-why worry. Most people are leaving in under ventilated homes epesially during the summer a/c season because of the lack of stack effect. More proof is that any home in a green grass climate geting an air change every 3 hours requires mechanical ventilation. Also they would get damp after an evening of 3 air changes. ---Unless they have supplemental dehumidification. Regards TB
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
Regular Guest
If it were sewer gasses causing a VOC measurement device to show readings off the charts, I would think that the house might have a sewer gas smell. Probably not the cause...
Regular Guest
Why doesn't your IAQ company test for methane! If they think it is sewer gas. Plus with out a carbon dioxide reading, you have no idea how much fresh air you are getting This should be a baseline test and should be with the first test you would take!!!
Professional Member*
I have bought stuff from Oregan Scientific. I have never seen an "Air Quality Monitor" listed. Do you have a model number? TIA.Is the Airadvice sensitive to "digestive emissions"? The Oregon Scientific "air quality monitor" is quite sensitive to them. It's not necessarily bathroom sessions; perhaps one of the water traps in your plumbing system has become dry (e.g., basement) and you're getting sewer gas in the house.
Remember, Air Conditioning begins with AIR.
Professional Member
ar112, not available anymore, probably didn't sell well.
http://www.amazon.com/Oregon-Scienti.../dp/B00006J047
Availability: Currently unavailable. We don't know when or if this item will be back in stock.
New Guest
You say that the monitor spikes on vocs at different times at those times what are the humidity readings and the temperatures. Are they different than others. It has been my experience that voc presence will rise if the humidity is too low,and that may be the reason they are more acceptable in the summer when the humidity is higher. However the chemicals in your home such as paints and glues will off gas for 7 years. Check the low humidity. 40 to 50% is a good range.
Regular Guest
Did you ever discover the culprit of the sporadically high VOCs?
We have this EXACT problem. We all wake-up ill nearly every night... Is been 4 months since we moved in: Our airthings monitor shows crazy VOC spikes. Always, and only, at night.
Was it the negative pressure? Or stuff coming from the furnace? If you found any answers, it would be a huge help to us!
Regular Guest
I'd be very skeptical of readings on the AirAdvice unit. They use a Honeywell ppbRAE3000 to calibrate at their shop and calibration, even on a ppBRAE3000 is touchy. Much less 1 step removed on the Air Advice. I speaking from direct experience with the ppBRAE3000. I've used this device many times for testing I've done
Also do you know if the *3000* reading is in ppb or ug/m^3. If it's in ppb the readings are exceptionally high and I would suspect you would smell something. If the readings are in ug/m^3 the readings are still high but not as bad.
Also if the AirAdvice is not using PID technology it's next to useless.
If you can take the AirAdvice outside. Readings should be very, very low - close to zero. If anyone tells you differently - they don't know what they are talking about (assuming you don't live under a freeway or next door to a unregulated chemical refinery or in S. Cal in the summer when ozone levels are very high). If readings are high outside the Air Advice is unreliable. Indoor VOCs are generated by what's indoors not outside. Particulate pollution is just the opposite.
Here a couple of suggestions to get accurate VOC readings:
1. Check out Home Air Check -https://homeaircheck.com/products/
For about $150.00 - 210 they will provide a test kit to take a calibrated sample your air. The sample is returned to Prism Labs and tested via Gas Chromatography/Mass Spectrometry. This is the gold standard for VOC testing.
Another provider is: : www.fikeanalytical.com. Fike is more expensive, but probably more accurate. One advantage of using Fike is that it includes a discussion with a PHD analytical chemist.
2. You can rent a real calibarted PID meter from Pine Environmental: http://www.pine-environmental.com/. They've got about 30 locations in the US. Price is about 150.00 for the weekend. This would immediately indicate if the Air Advice is misreading. If you do rent from Pine send me a PM for some tips on proper calibration before accepting the device.
My recommendation would be (1). This would provide the most accurate info. Also GC/MS testing indicates what types of VOC are detected. PID meters only indicate Total VOC levels without regard to type of VOCs. Also PID meters can not detect many VOC that GC/MS can.
If you do any of the test above and find a discrepancy with the Air Advice - I'd get my money back.
Here's a link to a pdf on the basics of VOCs, measurement and abatement:
https://www.dropbox.com/s/i6eor9zfh0...n%206.pdf?dl=0
Good Luck and I'd be very interested on what you find.
Regular Guest
Sorry, my bad. Just discovered this post originated in 08.
In any case - the info in my post still applies to your query.
If you're using one of the recently available consumer air monitor i'd be suspicious.
Check out HomeAirCheck. You might also want to see if your particulates high. See Dylos - http://www.dylosproducts.com/
Professional Member*
I hope we get a root cause on the complaint this time. I'm darn curious.
Professional Member
Would like to see what a ozone generator would do for your voc but wouldn't use one in a condo being afraid of ozone transfered to your neighbor. Built one with two plates from ebay and other parts put it in my crawl space and within 20 minutes could feel the o3. But with a sealed house and running it for 2 hours or overnight then ventilating the house then vacuum.Wondered if that would knock down the voc.
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