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  1. #1
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    Homeowner seeking advice with ERV

    Sorry for the following long post but I am at my whits end...

    I built a new ICF home in 2018. Because of the properties of this house, it requires a vent to the outside. I did most of the work on the home myself, using very few contractors, one of which was for heating and cooling. I trusted the guy and told him, install in my house what you would in your own. He gave me a price and I hired him. He installed a Bryant system: a modulating furnace, 20 SEER condensing unit, and a 200 CFM ERV, whole house humidifier, and a Bryant touchscreen thermostat. He finished his work near the end of 2018, where I paid him in full ($). I dont like when I dont understand things so I started looking at the system, the best I could tell, he didnt install the ERV. I contacted him and in 5 short months, he finally came out to install it. While he was here, I asked him if my thermostat could control the humidifier. When the humidifer was installed, he put a dedicated humidistat in but I saw that my thermostat measures humidity. Any how, he said that would be no problem. When he finished with the ERV, he told me that he misplaced the wire harness to wire it to the furnace so he would order another one and just leave it running on a timer for now. That same day, he "fixed" the humidifier and after that, I couldnt get it to come on. I also noticed that the ERV would run sometimes when the furnace didnt and wouldnt run other times when the furnace did. I assumed this was normal because it had no way to communicate back to the furnace because he misplaced the wire harness.

    So, fast forward in only 2 short months, he finally returned to wire the ERV to my furncace, after which, I saw no change in the way it ran, it just seemed to be running on the same timer.

    Also, the humidifier was still not working. Finally, I started looking into it and realized there is a terminal on the board, so I turned off the furnace, wired past the humidistat, wired one wire to the terminal and the other to the 24v power and it started functioning properly.

    Now, I am a utility lineman by trade and also have a bachelors in civil engineering. I like to work on cars, build things, blah blah. At no time did I question this guy because I trusted him. Well, I dont anymore. If he cant even get a simple humidifier to work properly, how can I trust him to feed me straight answers on this ERV.

    Hang in there, almost done:

    So, ideally, I would like to be able to control the ERV with my thermostat but I am not sure it has the capability this is ideal because I believe that an ERV is humidity transferring, meaning that the humidity outside effects the humidity inside. So, if its super humid out and I am cooling, I would like for it to be shut down.

    Basically, my question is, what should I do? Can someone on here help me get this figured out or is there someone in my area that I can hire to fix it that is trustworthy?

    Any help is greatly appreciated! I have pictures and model numbers if anyone is interested.

    Thanks for reading

    PRICING REMOVED BY ADMIN

  2. #2
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    Visit our contractor locator and see if there is someone near you.

    This sounds like a communicating system, so it will take someone with understanding of how this works. visit Carrier's site to see if there are local designated dealers, too.

    When you talk to potential contractors, be specific.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
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  3. #3
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    Thread Starter
    pacnw, thank you for the response. I will do so.

  4. #4
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    I am happy to hear about your desire to know how everything works. ERVs and HRVs are not well understood by most homeowners and are rarely used correctly. Most people are under the impression that "HRV/ERV reduces humidity. When you run the HRV/ERV the humidity in the house goes down." This is not correct. Running the HRV/ERV may increase, decrease or not impact the home's humidity depending on the outdoor conditions.

    Where are you located?

    What is the make and model of the ERV?

    How is it connected? Does it take return air from the bathrooms or is it a simplified connection where the return and supply are connected to the furnace return?

    I am not a fan of using humidity alone to control the ERV as it is not always a good indicator of the need for ventilation. As you mentioned if it is humid in the summer time and the ERV is set to run above a certain humidity then it will continue to bring in humidity in the summer when fresh air may or may not be needed and give the undesired effect of increasing the indoor humidity. In the winter time you may run into a situation where the ERV is drying the house and the humidifier is running to add humidity and the two systems are working against each other. You may also have a situation where there is a need for ventilation in the winter time and as a result you need the humidifier if the ERV over-dries the house in order to maintain good air quality.

    CO2 is a better indicator of the need for fresh air ventilation. If the CO2 concentration is too high the ERV runs. If the CO2 concentration is at a healthy level the ERV does not run. While this is happening there may or may not be a need to add humidity or reduce humidity via a humidifier and dehumidifier.

    In general ICF houses are very tight and have very little dry air leaking in during the winter. If the ERV is only running when people are home (and generating CO2) most airtight homes probably do not need a humidifier. Leaky homes may have so much fresh air coming in naturally they need a humidifier and rarely need the ERV to run. In my house for example we have an ERV that is run when needed by CO2 concentrations and our humidity has never been below 35% and we do not have a humidifier. 1986 built house with 2.5 ACH per hour (fairly tight) with 4 occupants, 2 of which are always home. Next year our youngest son will be in school and my wife will be back to work and the CO2 and humidity situation will change. This is all very application specific.

    The next best way to control humidity besides CO2 controller is to have a central control that allows you to run the unit on high speed, low speed or intermittently. VanEE for example has a controller (deco touch controller) that allows you to run the ERV on high speed, low speed or 20 minutes per hour but you need to manually change the setting. VanEE's platinum controller allows you to schedule ventilation (ie. you could have it run at low speed over night when you are home, 20 minutes per hour between 3 and 6 when 1 when one your kids is home from school but nobody else, high speed from 6-7 when dinner is generally made then back to low speed after 7pm). You can get an inexpensive monitoring system like the Netatmo Home Coach which allows you to remotely monitor CO2 levels in real time and help you decide when ventilation is needed.

  5. #5
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    So; did you buy a Energy recovery ventilator or a heat recovery ventilator?

    ERV tends to keep humidity where it is at. Brings moisture back into home in winter and keeps it out in the summer. Probably a good fit with ICF and super tight construction. Are you in a "green grass" climate or Desert climate?

    In a tight home I'd run the ERV 24/7 at the minimum ventilation level for the occupancy and volume of the space. So; do you have a dedicated duct system for the ERV or is it just "jumpered" between the FAU's return and supply? If "jumpered" then the FAU's fan will also need to run 24/7 to properly ventilate the structure.
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  6. #6
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    jdaley, wow, thats a lot of great information! Thank you for taking the time to respond.

    I have a Bryant ERVXXLHB1200.

    As far as how it is connected, I have an intake and an exhaust through the outside of my house, so each of those connect to it. The other two connect to the main supply from the furnace.

    I never even considered why you would need an ERV for fresh air other than just the fact that the house was tight. I didnt even think of CO2 when setting up a schedule to run the ERV. This makes complete sense!

    Youre right on not needing a humidifier, I had a whole house humidifier installed and it barely ever runs. As a matter of fact, last summer, before the ERV was installed, I had a hard time keeping the humidity below 55%. At this time though, there was just 1 hole in the side of my house and it was connected to the furnace, so I feel like it was pulling in outside air all the time.

    After I get done responding to you, I will look up the controllers that you have mentioned.

    This is definitely a step in the right direction of me understanding the workings of my system. Thanks!

  7. #7
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    Juan, thanks for your response.

    Its an Energy Recovery Ventilator.

    I live in central IL, so I guess I would consider that a green grass environment? It does get cold here and snows, but we also get temps up to 100 in the summer months.

    Based on your description, the duct is "jumpered". So, there is a button on the unit, press once for low speed, another time for high speed and the third time turns it back off, this is where the unit can be controlled by something else, whether is be a dedicated controller or wired to your thermostat. You think I should turn it on low and leave it, but then also run my fan on my furnace on low for 24/7?

  8. #8
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    Fan "on" low 24/7 is best for recirc and blinding of fresh air into the home. A fresh air change in 4-5 hours is suggest when the home is occupied. Cold, windy days naturally change even in a tight home. Mild calm weather in a air tight home is lucky to get a fresh air change in +12 hours. CO2 is best to control any fresh air ventilation. Amazon CO2 controller is slightly + hundred $. Set for fresh air when +650 PPM. With one person, 650 ppm is about 50 cfm of fresh air. The air flow should be about a fresh air change in 4-5 hours. 2,500 sqft. home is 80-100 cfm.

    ERVs do not provide make-up air for exhaust devices like the clothes drier and kitchen hood. Any open combustion devices may back draft when the kitchen hood or clothes drier operate.

    In my home, I ventilate when the CO2 is +650 ppm An ERV or HRV will not control %RH. As others stated, humidifier may be needed when the outdoor dew point <50^F. A properly setup a/c should be able to remove the moisture from fresh air infiltration, ventilation, and occupant moisture while significant sensible cooling loads are present. Evenings and rainy day will require a dehumidifier.
    If the home has a basement, a dehumidifier will also be needed during most of the mild months of the year. Personally, I would prefer a small whole house dehumidifier with the fresh air option in mild, green grass climates like yours.

    Keep us posted on the steps you take and results.
    Regards Teddy Bear
    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"

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