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  1. #1
    Join Date
    Jul 2010
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    15

    Trane Fresheffects 200CFM ERV install. Please provide feedback

    Hello,
    I am in Portland, OR and I have the ERV installation scheduled early november. It will be a Trane Fresh effects 200CFM. Home is a 2700 sq ft home with a Trane XV90 (variable speed fan) furnace and a Trane Heat pump. I have been monitoring the CO2 levels inside the house and it averages 600-700ppm. In the thick of winter I expect it to be worse and hence the ERV install. The unit will be installed in the garage (insulated) and ducted to the furnace. Please provide feedback on

    1. What are the things to ensure? For example, I read that in one installation, the installer didn't insulate the intake and exhaust which resulted in a major redo. I want to avoid things like that. Please recommend if such insulations are needed.

    2. Length of runs for the intake and exhaust? Any requirement on how far they have to spaced apart?

    3. I have a honeywell f200 in-line merv 12 filter. Sometimes I use merv 13 and am considering Merv16 Lennox during cold/flu etc. Does the percentage of time the ERV comes on, have any implications on the filteration system in terms of how often to replace filter and workload on the furnace, thermostat settings etc

    There will be holes cut out in the garage wall to accommodate the intake and exhaust. Any precautions to be taken there. Basically any feedback or recommendation you have will be much appreciated.
    Thanks,
    -Jai

  2. #2
    Join Date
    Aug 2003
    Posts
    907
    In the winter one would expect less CO2, not more, because the stack (chimney) effect causes more air exchange with the outside. Did you actually monitor CO2 during winter? 700 is nothing to worry about. Offices typically don't ventilate for less than 1000 ppm. If anything your indoor plants will grow better.

    If you're worried about the flu and colds, the best thing you can do is maintain >30% humidity in the house (e.g., 35%). Trying to capture viruses with a furnace filter is futile.
    -If you won't turn it on then nothing else matters.

  3. #3
    Join Date
    Jul 2010
    Posts
    15
    Quote Originally Posted by pmeunier View Post
    In the winter one would expect less CO2, not more, because the stack (chimney) effect causes more air exchange with the outside. Did you actually monitor CO2 during winter? 700 is nothing to worry about. Offices typically don't ventilate for less than 1000 ppm. If anything your indoor plants will grow better.

    If you're worried about the flu and colds, the best thing you can do is maintain >30% humidity in the house (e.g., 35%). Trying to capture viruses with a furnace filter is futile.
    I got the monitor just a few months ago, so no there are no data points for winter yet. However, the windows always remain closed for extended periods of time during winter. The building is very well sealed so I am not sure to what magnitude the stack effect would impact in bringing in fresh air. Of course there are leaks from exhaust fans, it remains to be seen. If I can improve the quality of the indoor air to near fresh air levels, that is even better. More than a worry I see this as an opportunity to improve indoor air quality. Humidity is already well controlled. The furnace filter is not to capture disease causing bugs per say, but rather to avoid viruses/bacteria circulating throughout the house when/if they get into the ducts. Make sure that no one coughs hear the return next time . The install is going to happen regardless, so it is worthless to question the need for an ERV right now.
    Do you have any inputs for my questions?
    Thanks!

  4. #4
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451
    I would monitor the CO2 PPM with the windows closed over night would be a meaningfull number and the fan running. Knowing the CO2 ppm tells you the amount of fresh air you are ready getting. Two adults, 2 kids in 2,500 sqft with 900-1,000 PPM CO2 is an air change in 5 hours. This OK. More may be better.
    Most home with ERVs will be over-ventilated during cold winter weather. Keep us posted on the CO2 levels next winter with the ERV operating.
    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"

  5. #5
    Join Date
    Jul 2010
    Posts
    15
    Quote Originally Posted by teddy bear View Post
    I would monitor the CO2 PPM with the windows closed over night would be a meaningfull number and the fan running. Knowing the CO2 ppm tells you the amount of fresh air you are ready getting. Two adults, 2 kids in 2,500 sqft with 900-1,000 PPM CO2 is an air change in 5 hours. This OK. More may be better.
    Most home with ERVs will be over-ventilated during cold winter weather. Keep us posted on the CO2 levels next winter with the ERV operating.
    Regards TB
    Thanks for the suggestion. Actually I bought the CO2 monitor based on your suggestion and it was an eye-opener. Are there any issues with over-ventilating other than higher cost of operation? The CO2 monitor will help me modulate and set the ERV operation. I work in a fairly large building with lots of people (open cubicles) and was surprised to see levels of < 500 ppm throughout the day. It was refreshing to see that. They must have a good ERV in place to achieve those levels and they probably want all the neurons functioning at peak, so the more fresh air, the better productivity

  6. #6
    Join Date
    Jul 2010
    Posts
    15
    The install is scheduled for tomorrow morning. I would really appreciate feedback on two questions.
    1. How far apart (minimum) should the intake and exhaust be spaced apart?
    2. Should both the intake and exhaust be insulated?
    Thanks,
    -Jai

  7. #7
    Join Date
    Jul 2010
    Posts
    15
    This link suggests they should be at least six feet apart. Is this important?

  8. #8
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451

    p

    The distance between is to avoid exhaust air from being picked up by fresh air inlet.
    Regarding CO2 levels, how high are yours after a typical night with good air mixing and open interior doors? Two people in 25,000 cubic feet of space with 800 ppm CO2 are getting an air change in 6 hours. This is good. Overventilating makes space excessively dry during low outdoor dew points and wet during high dew points. Glad you were concerned about IAQ.
    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"

  9. #9
    Join Date
    Jul 2010
    Posts
    15
    Quote Originally Posted by teddy bear View Post
    The distance between is to avoid exhaust air from being picked up by fresh air inlet.
    Regarding CO2 levels, how high are yours after a typical night with good air mixing and open interior doors? Two people in 25,000 cubic feet of space with 800 ppm CO2 are getting an air change in 6 hours. This is good. Overventilating makes space excessively dry during low outdoor dew points and wet during high dew points. Glad you were concerned about IAQ.
    Regards TB
    After a typical night in the room with doors closed it is over 1200 ppm. In the landing area when we open the interior doors it ends up around 700-800. RH is around 40-50 with temp in the 65-70 range. Hope the ERV will give me more control in modulating fresh air. At some point in the thick of winter we will have humidifiers going full steam for a majority of the day. Just having more knobs would help dial in to desired comfort. There will be compromises when outdoor dew points are too low or too high. Thanks for the feedback.

  10. #10
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451
    1200 ppm CO2 in the bedroom with the door closed with 2 occupants is very good. Consider that the CO2 is introduced into a confined space and the therefore the CO2 levels are higher near the source. 1200 ppm indicates 10 cfm of fresh air per person is being mixed with CO2 in the bedroom.
    I suggest that when CO2 at 800 ppm in the open space and 1200 cfm in a master bedroom with two, indicatew ok fresh air in the home. Higher CO2 levels suggest the need for more fresh air.
    Keep us posted on your results.
    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"

  11. #11
    Join Date
    Jul 2010
    Posts
    15
    Quote Originally Posted by teddy bear View Post
    1200 ppm CO2 in the bedroom with the door closed with 2 occupants is very good. Consider that the CO2 is introduced into a confined space and the therefore the CO2 levels are higher near the source. 1200 ppm indicates 10 cfm of fresh air per person is being mixed with CO2 in the bedroom.
    I suggest that when CO2 at 800 ppm in the open space and 1200 cfm in a master bedroom with two, indicatew ok fresh air in the home. Higher CO2 levels suggest the need for more fresh air.
    Keep us posted on your results.
    Regards TB
    Thanks for the useful pointers.
    Is CO2 a reasonable proxy for other indoor pollutants? In other words, which is the major pollutant inside a house in general (ignoring dust and pollen that we can assume is filtered by a good Merv11 filter)? There is radon, stuff from daily cooking, gases from particle boards, the list maybe endless, and not everything is measured and monitored like the CO2. That makes me wonder if CO2 is a good proxy (if high other pollutants are high, if low, others are low, I mean being directly proportional) for other indoor pollutants. Asked another way, is the mixing ratio of CO2 similar to other indoor pollutants?
    Thanks.

  12. #12
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451
    CO2 is an indicator of the presence of occupants and a absence of fresh air change. People are in the home and the air change rate is indicated by the number of occupants verses CO2 ppm.
    Most homes have an excess of volitile organic compounds, most commonly is formaldehyde.
    Without occupants present, why ventilate? With occupant present, and enough natural ventilation to keep the CO2 levels low, why ventilate?
    Analize the CO2 level and the number of occupants, you can figure out the real air change rate of most structures.
    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"

  13. #13
    Join Date
    Jul 2010
    Posts
    15

    Is my ERV system working the way it should?

    The install completed yesterday but I am not sure if it is working the way it is intended to and if something needs to be changed with the low-voltage wiring. It is ducted such that fresh air from outside goes into the furnace return after being conditioned by the fresheffects. Stale air from inside is exhausted out indirectly conditioning (warming/cooling) the fresh air coming in. The switch is a % time control in increments of 10 staring at 10%.

    What works:
    The furnace fan comes on when the fresheffects turns on based on the timer.

    What is unexpected:
    The fresheffects comes on every time the furnace turns on. The timer switch goes blank (as in disabled) and probably gets reset.

    What I expected:
    The furnace fan comes on when the fresheffects turns on based on the timer. If set for 10%, it should for 6 minutes every hour and stops regardless of the furnace/ac being on/off. I don't want the fresheffects to turn on every time the furnace comes on.

    Is this the right expectation from the unit?
    Last night the thermostat was set at 65, and is normally 70 during the day. Apparently past midnight it was blowing cold air through the vents. How cold I don't know. I guess it is because the inside temp was around 68 and the fresheffects came on, furnace fan was on, but heating was off. The only heat is from the exchange in the fresheffects. If it is 30 degress outside and 65 degress inside, what temperature can be expected at the vents? Without an active heating system, can the fresheffects warm cool air at 30 degress close to 65 degress?

    Please correct me if I am wrong in my line of thinking.
    Thanks,
    -Jai

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