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  1. #1
    Join Date
    Feb 2012
    Location
    colorado
    Posts
    12

    ERV/HRV and elimination of cooking odors

    IN BRIEF, HERE'S MY QUESTION:
    Will getting an ERV air exchange vent system help eliminate cooking odors from my house and make a significant improvement in our IAQ from our current set up? How much will it help reduce our utility bills?
    Thank you! Tom


    We are currently under contract to purchase a new home in eastern Colorado. It is a ranch-style house with a finished basement, 10' and 9' ceilings, total 3200 Ft^2 or about 30,400 cubic feet. We will have a high-efficiency Lennox G61MVP with variable speed fan and a Honeywell F300E 20x25" electronic air cleaner. It has a pre-filter and optional carbon post-filter, which I will likely use. I think they are dry-walling the house now, making any major changes to the system now more difficult. http://hvac-talk.com/vbb/images/smilies/gah.gif

    The house ventilation system is a Panasonic 80 CFM fan in the laundry room on the main floor. The fan will be set to run 20 min every hour (or 5% of the house air volume every hour). It is to be synced with a damper for passive inflow of outside fresh air into the return register duct.

    In the new house there will be a kitchen stove hood with fan vented to the outside, which should help some (we do not have one at our current home that we are moving out of in a couple months). The main floor is a fairly open plan with no walls between the kitchen and the living area. There is a main return duct at the far end of the living/family area. There is a second return near the secondary bedrooms, and also in the basement. We have jumper ducts between the rooms on the main floor.

    From all that I've read, ideally we would need about (0.15-0.3 x 30400)/60 = 76-152 CMF continuous ventilation. Per tech at Venmar, based on the # of rooms in the house it would be 140 CMF to "meet code" (whatever she meant by that).

    To me, switching to ERV at somewhere in the range of 100-140 CMF would seem to be an ideal solution for the following reasons:
    1) My wife is pregnant and very VERY sensitive to cooking and other odors (which may be a recurring condition if we are lucky). We (translation, I) basically have to open the windows in our current location at meal times for her not to barf from the cooking odors.
    http://hvac-talk.com/vbb/images/smilies/gah.gif
    2) With a new baby soon, I want to minimize the hazards of off-gassing VOC's and improve IAQ
    3) I just learned there is some data to suggest having good ventilation (fan, open windows) may reduce the incidence of SIDS (sudden infant death syndrome), but rather not have my wife opening and closing the windows all the time, plus the security risks.
    4) Hope to retain some humidity in the house with the ERV (vs. HRV) as we are essentially in a desert environment.
    5) Seems kind of a dumb concept to build a tight, energy-efficient house, then realize you can't breathe in it, so the solution is to poke a hole in it and let cold (hot) air in. genius http://hvac-talk.com/vbb/images/smilies/censored.gif
    6) we live just outside an area with VOC's in the ground water. So really only a theoretical risk, but I would feel better about more ventilation in the home. We do have an active radon system under about 80% of the house then a conditioned crawlspace under the remain 20% (for whatever sense that design makes!).
    7) Wife also has bad seasonal allergies and does better indoors with the A/C on for a good part of the year. Therefore, we can't always rely on open windows for ventilation. Also the neighbors are about 10' away (not a zero lot line property, but close) and I don't know how noisy they will be.

    I just talked to 2 HVAC guys in our area and they both discouraged me from getting an ERV as a solution to the cooking odor problems. They tried to sell me on a rgf phi (photohydroionization) which I am against based on the EPA recs and a study that showed increases in formaldehyde with PHI use. Also tried to pitch me on the Trane clean effects, but I opted for the Honeywell as it was an available option with the house and seems to maintain it's efficiency better with dirt loading.

    Sorry for the length, thank you very very much for you comments!

  2. #2
    Join Date
    Aug 2000
    Location
    Central Oregon
    Posts
    749
    Our customers use high cfm exhaust fans in their range hoods to control Cooking odors. Code most every where requires a make up air source when over 400 CFM though.
    Recircing through your heating system charcol filter will remove them very slowly.

    hrv/erv is for air exchange energy savings. which help with #5 on your list. You can control the air comming in and out with a tight house or you can live at the whim of mother nature infiltrating/exfiltrating whenever and through areas unknown to you. This not only affects you but it affects your home.
    If you think our goverment is screwed up. You haven't lived in another country.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,646
    Good to hear from someone concerned about his family. Selecting the right equipment depends on how air tight the home turns out. A moderately air tight home probably get enough fresh air during cold windy weather yet needs mechanical fresh air during calm weather or a boost during cooking. This type of ventilation is most practically done by a good kitchen hood and a simple exhaust fan that will change the air in the home in 4-5 hours when the home is occupied. This is necessary to purge indoor pollutants and renew oxygen.
    If this was a extremely air tight home with a high heating cost, the erv could have some merit. Kitchen exhaust is best done with simple exhaust because of grease and short time of use.
    Keep up the concerns for your family. Keep us posted.
    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"

  4. #4
    Join Date
    Feb 2012
    Location
    colorado
    Posts
    12
    Thank you. The general sense I get is that you would mostly do it for the energy savings, but not for the other reasons. Is that right?

  5. #5
    Join Date
    Aug 2000
    Location
    Central Oregon
    Posts
    749
    Quote Originally Posted by teahouse1 View Post
    Thank you. The general sense I get is that you would mostly do it for the energy savings, but not for the other reasons. Is that right?
    Yes.
    If you think our goverment is screwed up. You haven't lived in another country.

  6. #6
    Join Date
    Feb 2012
    Location
    colorado
    Posts
    12
    If I go to an (ERV) air exchange system, where does all the make up air for the kitchen hood fan (225 CFM), bathroom fans, and dryer come from??!?! (furnace and water heater have their own intakes). Do you need to balance the system slightly positive (in). Or do you get enough of an increase in flow into the house with a favorable pressure differential to compensate?

    If the mantra is: filtration, circulation, and ventilation... I think our current system comes up a bit short on ventilation and I will continue to look into finding someone to work with me on this project or may consider doing it myself. Any recs on someone in the Denver area?

    Thank you!

  7. #7
    Join Date
    Dec 2010
    Location
    Toronto
    Posts
    1,253
    This has always been an issue and you cannot use an ERV for a kitchen exhaust so if the high CFM exhaust is running it usually just draws air in through the ERV through DE-pressurization and some normal infiltration.

  8. #8
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,841
    Without realizing it, you're asking for two solutions, not one.

    The first addresses the IAQ issue rather extensively. I'd recommend a blower door test be done on the house as well as a duct blaster test to determine the tightness of the house beyond question. Knowing the duct leak rate is also important and that data can be obtained using the blower door equipment or a separate test, just FYI. The ERV is a good solution to assist with the IAQ issues. You've stated you have an EAC for particle removal but I didn't see any reference to a non-ozone Ultraviolet Light (UVL). A UVL of proper watt output will aid in the prevention of living organism colonization through changing the DNA of those organisms. This is the product, when properly sized and maintained, that can minimize the exchange of cold and flu germs and is a welcome addition to the IAQ issue.

    The stove hood/food odor question is a secondary issue. If you have a tight house (see blower door test results) then operating the stove hood as the house is currently constructed will be akin to sucking liquid through a straw that has a piece of tape of the immersed end! Not much can get out through the straw because the inlet to the straw is blocked. This is what will happen in a tight house when the fan is turned on. You can't suck air out because you don't have air coming into the house. This is called make-up air and is needed whenever an exhaust fan (bathroom, kitchen, non-sealed combustion appliance, non-sealed fireplace, central vacuum cleaner, clothes dryer) is activated in the house. So you'll need to allow for make-up air into the home, which can be passive or active but one way or the other, you'll need it.

    To summarize, you've got a ERV which removes and bring in an equal amount of air for a net zero pressure change in the house. Then you've got the blowers and other things appliances in the house that just remove air, thus putting a tight house under a negative pressure. You need a method of equalizing that negative pressure back to zero.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  9. #9
    Join Date
    Feb 2012
    Location
    colorado
    Posts
    12
    Quote Originally Posted by SolarMike View Post
    This has always been an issue and you cannot use an ERV for a kitchen exhaust so if the high CFM exhaust is running it usually just draws air in through the ERV through DE-pressurization and some normal infiltration.
    Thanks Mike.

    Understand can't hook the ERV stale air return from the hood or too proximal to the kitchen as the CFM is too high and the ERV filters and heat exchanger would clog with the junk from the kitchen.

    In contrast to skippedover, sounds like you would not necessarily recommend a second make up fresh air inlet to compensate for losses out of the house from exhaust fans and the like at under 400 CFM. Sounds like you feel there would be enough make-up air brought into the house via the ERV via increased intake due to the pressure changes.

    It all certainly seems more complicated that I originally thought. you guys work in a very interesting field with a lot of new technology.

    Thanks!

  10. #10
    Join Date
    Feb 2012
    Location
    colorado
    Posts
    12
    [QUOTE=skippedover;12595311]Without realizing it, you're asking for two solutions, not one.

    You've stated you have an EAC for particle removal but I didn't see any reference to a non-ozone Ultraviolet Light (UVL).


    Here's my issue with above... below is from a published study conducted by the Lawrence Berkeley National Laboratory

    Abstract Ultraviolet photocatalytic oxidation (UVPCO) systems for removal of volatile organic compounds (VOCs) from air are being considered for use in office buildings. Here, we report an experimental evaluation of a UVPCO device with tungsten oxide modified titanium dioxide (TiO2) as the photocatalyst. The device was challenged with complex VOC mixtures. One mixture contained 27 VOCs characteristic of office buildings and another comprised 10 VOCs emitted by cleaning products, in both cases at realistic concentrations (low ppb range). VOC conversion efficiencies varied widely, usually exceeded 20%, and were as high as 􏰀80% at about 0.03 s residence time. Conversion efficiency generally diminished with increased airflow rate, and followed the order: alcohols and glycol ethers > aldehydes, ketones, and terpene hydrocarbons > aromatic and alkane hydrocarbons > halogenated aliphatic hydrocarbons. Conversion effi- ciencies correlated with the Henry’s law constant more closely than with other physicochemical parameters. An empirical model based on the Henry’s law constant and the gas-phase reaction rate with hydroxyl radical provided rea- sonable estimates of pseudo-first order photocatalytic reaction rates. Formal- dehyde, acetaldehyde, acetone, formic acid and acetic acid were produced by the device due to incomplete mineralization of common VOCs. Formaldehyde outlet/inlet concentration ratios were in the range 1.9–7.2.
    Practical Implications
    Implementation of air cleaning technologies for both VOCs and particles in office buildings may improve indoor air quality, or enable indoor air quality levels to be maintained with reduced outdoor air supply and concomitant energy savings. One promising air cleaning technology is ultraviolet photocatalytic oxidation (UVPCO) air cleaning. For the prototype device evaluated here with realistic mixtures of VOCs, conversion efficiencies typically exceeded the minimum required to counteract predicted VOC concentration increases from a 50% reduction in ventilation. However, the device resulted in the net generation of formaldehyde and acetaldehyde from the partial oxidation of ubiquitous VOCs. Further development of the technology is needed to eliminate these hazardous air pollutants before such a UVPCO device can be deployed in buildings.

    FROM: INDOOR AIR
    doi:10.1111/j.1600-0668.2007.00479.x
    Performance of ultraviolet photocatalytic oxidation for indoor air cleaning applications
    A. T. Hodgson1, H. Destaillats1,2, D. P. Sullivan1, W. J. Fisk1
    1Indoor Environment Department, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA, 2Department of Civil and Environmental Engineering, Arizona State University, Tempe, AZ, USA
    Key words: air purification; formaldehyde; clean air delivery rate; titanium dioxide; tungsten oxide; volatile organic compounds.
    Alfred T. Hodgson Indoor Environment Department Environmental Energy Technologies Division Lawrence Berkeley National Laboratory 1 Cyclotron Road 90R3058 Berkeley CA 94720 USA Tel.: +1 510 486 5301 Fax: +1 510 486 6658 e-mail: athodgson@lbl.gov
    Received for review 23 August 2006. Accepted for publication 21 November 2006. Ó Indoor Air (2007)

  11. #11
    Join Date
    Dec 2010
    Location
    Toronto
    Posts
    1,253
    I have, in the long distant past, done some tests on a really tight house to see where the infiltration happens when kitchen exhaust fan comes on. On the particular house we worked on, the CFM through the HRV increased considerably due to the kitchen fan. There may me some reason that current equipment might not allow that but I doubt it.

  12. #12
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,841
    [QUOTE=teahouse1;12596661][QUOTE=skippedover;12595311]Without realizing it, you're asking for two solutions, not one.

    You've stated you have an EAC for particle removal but I didn't see any reference to a non-ozone Ultraviolet Light (UVL).


    Here's my issue with above... below is from a published study conducted by the Lawrence Berkeley National Laboratory

    Abstract Ultraviolet photocatalytic oxidation

    Who said anything about photocatalytic oxidation? I suggested a straight UVL, nothing about photocatalytic oxidation UVL.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  13. #13
    Join Date
    Feb 2012
    Location
    colorado
    Posts
    12
    Some new photos. They installed insulated 8" flex duct to 2 vents. One for exhaust, one for fresh air intake to the (future) ERV. You can see the fresh air vent hood far off by the electrical panel. The exhaust is on the opposite side of the house. I'm guessing the total run is about 40 feet. They also seem to run it right over the top of the main HVAC supply trunk, but I can't completely tell.

    Is this going to be too long a run for a typical home ERV unit on the fresh air supply and exahaust lines?

    Do you need to keep this flexi duct off the hot HVAC ducting. Can I just slip some duct board in between the two as a solution.


    Thank you very much!
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