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Community and Q&A

Balancing Intelli-Balance 200 ERV

Shawnnixon1 | Posted in General Questions on

Just hired someone to do dedicated ductwork for erv since I dont have an HVAC system, just electric baseboard he did a clean job however at the end found out he does not know how to balance and said the units he installs balance on its own….and said I dont need to balance.

How important is it to balance? From the picture below it seems like something I can do?

panasonic erv 200cfm
1800 sqft house 400sqft basement, we have one exhaust and one intake on each floor except basement only has intake which was already there and he just connected that duct through the roof when he was installing the new one for the 2 floors (noticed the air sucking in basement is weak compared to the upper 2 floors even on 200cfm? He said I can close the vents abit upstairs to make it equal.

Last question (sorry) how long will it take for the house air to be exchanger the way my set up? I have 1000ppm of co2 in the house right now

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  1. Shawnnixon1 | | #1


  2. Expert Member
    Akos | | #2

    Easy to do but you need a good differential manometer (avialable from your e-retailers for a couple of bucks). The unit does have dials to set the flow but it is not perfect, by measuring the actual flowrate, you can get it spot on. Make a note what the flow rate corresponds to on the dials in case you ever want to adjust it.

    A properly sized ERV takes about 3 hours to fully cycle the house air.

  3. DennisWood | | #3

    The point of “intellibalance” is that the ERV ramps the EC motors to whatever you set the dials to for CFM. Start with 100CFM continuous and then increase or decrease from that based on your CO2 readings.

    Balancing is important, but you “should” be pretty close on that unit as the motors adjust to static pressure. Just make sure the dampers are fully open now.

    Balance is important for two reasons:

    1. Heat exchange performance at the ERV core will be affected if it is not balanced.

    2. You can negatively or positively pressurize your home…and neutral is what you want, particularly in cold weather. Forcing warm/moist air into a cold building envelope (positive inside pressure) is not a good idea.

    You can measure the balance using that chart you included and a 0-0.25 in/hg Differential Magnahelic gauge like this one:

    You connect at the fresh ports with the two hoses (you will need to source these, they do not ship with the gauge) connected to the gauge and then do the same at the stale ports. Your chart shows you what the gauge will read at the given CFM.

    You will probably find that little damper adjustment is required if both exhaust and intake CFM are set the same. The unit should be balancing itself. I believe it does this electronically by comparing torque/current used by each motor to an internal table of CFM values. Checking with a magnahelic differential gauge will confirm this is working correctly, and allow you to fine tune with the balancing dampers.

    1. Shawnnixon1 | | #4

      Thanks alot for your help, the installer ziptied the ducts so tight it was crimping the duct, i broke all the zip ties and let it loose hope this will help??

      If you look at the attachment in the manual page it says i just need to attach the balancing tool onto the 2 holes and not the tubes? Is this something easy I can do?

  4. DennisWood | | #5

    The gauge has two nipples with I think 1/8" OD. Just order up some tubing. You may need to figure out a male end to go into the ERV pressure ports...or just order this which is inexpensive and simple:

    Using your balancing chart, and assuming the CFM dials on ERV are set to 100 CFM:

    You don't have a forced air furnace, so you can go straight to balancing. Make sure all your supply and return vents are fully open.

    1. Make sure the magnahelic gauge is level and plumb if using the manual one I linked. Set it to zero using the adjust screw on front.

    2. Connect probes to the fresh ports. If the gauge reads negative, reverse the tubes. At 100CFM it should read 20 Pa. If it doesn't adjust the damper on your supply. If the installer did not install one, you may have to.

    3. Connect probes to the stale air ports. If the gauge reads negative, reverse the tubes. At 100CFM it should read 20 Pa. If it doesn't adjust the damper on your return. If the installer did not install a damper, you may have to.

    Its pretty simple. Check the balance at whatever you set the CFM dials to. You are measuring pressure drop across the ERV core which has been tested at the factory to correlate to those CFM/pressure numbers.

    You may want to look over this as well:

  5. Shawnnixon1 | | #6

    Its running on max speed 200cfm not balanced and co2 on main floor went from 1000-1200 to 580-640,
    Top floor bedrooms around 700-800 from 1200
    Basement around 780-820

    If you see the installation the unit is hidden on the right room, do you think these curves will make cfm drop alot? Is it better just to put it on the left room?

  6. DennisWood | | #7

    I would not loose sleep on those curves. You could use support webbing (1 3/4 or 1 1/2" wide) vs the tie wrap on the support in pic 2 to make sure it doesn't restrict the duct over time.

    200 CFM is likely over ventilating for your setup. You may be throwing BTUs out the door, but I'm sure you'll find a balance you are happy with :-)

  7. Shawnnixon1 | | #8

    Dennis it seems like any hvac contracter in montreal dont balance I called over 30 companies…thanks alot for your help where can I buy those webbing?

    Im assuming if I lower the CFM then the co2 is going to up? I cant believe at max cfm is where its able to bring down co2 on main floor to 640 or so….for some reason the basement return is not as strong as the rest (installer connected a T in the roof to connect to the old duct that was installed with the house in 2004 but all other flex duct is new.

  8. Shawnnixon1 | | #9

    Will it be a big difference if I put it in the other room where all the ducts will go up straight except the fresh air intake coming from this room

  9. DennisWood | | #10

    Keep in mind that below freezing it will spend some time in defrost mode.

    You don't have a forced air system to move air around, so I'm guessing C02 levels near your ERV supply outlet will be quite low, and will increase as you move away. It will take some time for levels in your house to come down. If you lower CFM, yes, levels will go up. Just run it for a few days and see how it plays out. You'll find on windy days you may not even need to run your ERV.

    Webbing... or if you have MEC store, they carry it too. It's nothing special..just wider webbing.

  10. Expert Member
    Akos | | #11

    The unit does autobalance but within limits, about 0.4" WG for both interior and exhaust ducting.

    Your ducting doesn't look to be the best, 6" flex at 200CFM can add a fair bit of loss. Once you go above the autoblance limit, the unit will go out of balance, this is why you need to balance your setup with gauges.

    The gauge that Dennis linked to is a good one but a bit too low range, you want the version that goes up to 1" WG. If you are shopping online, lot of the digital ones are rated for 3PSI which is way higher than you need and you won't get much accuracy. The 2PSI ones are better, but a 1PSI max gauge would be the best.

    1. Shawnnixon1 | | #12

      I found someone who knows how to balance he said the meter is a cfm meter and he adjusts the dampers accordingly is this what balancing is?

      If you can share where I can buy it online really appreciate that

      1. Expert Member
        Akos | | #20

        A good one is a Fluke 922 but pretty spendy. There is a Klein ‎ET180 which is much more reasonable cost. There are also MANY on Amazon but you'll have to check the specs as most are for +/-3PSI. You want 2PSI or less.

  11. DennisWood | | #13

    Good catch there AKOS, yes..the 0-.5 is what he wants (or better) as at 200 CFM you need to measure .4 in. I have the 0-.5 and would prefer a 0-.25 for accuracy at lower CFM.

    Shawn, there is balancing at the ERV and balancing at the vents. They are not the same. A proper flow hood would be required technically, but you can approximate yourself with a hand held anemometer (like $40 from amazon). It will provide LFM (velocity) which you can convert to CFM if you know the duct size. It's hard to do a super accurate job this way, but you can get relative flows decently accurate. There are other methods (like time a garbage bag filling at the vent) but the meter is the easiest IMHO.

    The fellow you talked to likely has a flow hood for measuring output at the ducts. If he also has a differential magnahelic to balance at the ERV as well, then hire him.

  12. Shawnnixon1 | | #14

    The installer kept telling me to put one supply on each floor and the return in the basement but I made him put a supply and return on each floor but basement return only…is there a benefit to what he said?

  13. DennisWood | | #15

    You have a standalone system, so a supply and return on each floor is a good idea. You have a lot more options for balancing too if you have both supply and returns strategically placed on each floor. The typical recommendation is to have supply to main living areas and bedrooms, and return in bath, laundry and kitchen.

  14. Shawnnixon1 | | #16

    Is it normal for co2 to be more than the previous day but 2 more poeple in the house? Even were all upstairs in the bedroom, downstairs co2 level is 650-680 when the previous day when we were upstairs it was 570-580 downstairs

  15. Shawnnixon1 | | #17

    All this is with 200CFM, I’m not sure why he used flex duct all the way and metal only on elbows….all 4 ports for unit is flex duct all the way up from basement

    Do you think if I move the ERV to the left room and run all the flex duct straight up instead of all those curves will make a difference?

  16. Shawnnixon1 | | #18

    I just saw sticker on the flex duct it says “air conditioner” on top and under “length maximum installation 14 feet” but this duct is like way over 25 feet

  17. Shawnnixon1 | | #19

    This is what he used as ducts…it says air connecter!?!? Is this the reason the airflow is bad? I just checked online how air connecter and flex duct is not the samething

    1. Expert Member
      Akos | | #21

      People, pets and plants are the source of CO2 in the house. You have more people, the CO2 will go up.

      In terms of ducting. 6" flex is fine for 120 or so CFM but way undersized for 200CFM. If you want to run at 200, you need 7" at least, 8" is better if you have long runs. Most likely you are currently not getting 200CFM on the unit as the ducting is restrictive. Keep in mind that 200CFM is a lot of ventilation airflow, most houses run under 100CFM.

      The air connector label is for commercial drop ceiling install where you don't want long runs from main trunk to registers, this is not the case for your ducting. You can do long runs of flex but you have to watch flow rate and size.

  18. DennisWood | | #22

    Shawn, it sounds like you have three branches off the main trunk. So you could run 8"-10" duct to where the first branch occurs, at which point you're ok. It's that first stretch of 6" that would be restrictive if you continue to ventilate at 200 CFM. This diagram will help:

    From page 9 of this manual

    But again, running 200 CFM would be considered "over ventilating" your space. Commercial air quality targets are generally in the 800 CFM area, and getting a space consistently to 500 PPM with four people in it will be a challenge.

  19. Shawnnixon1 | | #23

    Online it says air connecters are not flex duct? And max should be 14 feet….the recommended duct for this says 6” on panasonic, the ports are also 6” i domt have space to go higher, he installed a real flex duct the silver one for exhaust from the unit to outside but the rest are the black “air connecters” dont use more than 14 feet.

    What if i I put the ERV in the other room so theres no bends, only for the fresh air intake to machine 8 feet and i will put a rigid elbow instead of this flex and from the erv to the top floors put rigid duct and leave the ones in the attic with the remaining “air connector” since it should be running around 14 feet accross to come down to my kitchen? Will this make a big difference?

  20. DennisWood | | #24

    How big are the hoods/openings in your outside walls for exhaust and fresh air?

    Shortening the run to the outside, and using hard duct will make a difference, but see that diagram I posted above for recommended duct sizes at different CFM. That was from a 200 CFM venmar unit.

    1. Shawnnixon1 | | #25

      This is the hood vent:

      If I move the other room so the runs are straight up for exhaust and supply to the 2 floors but i keep the fresh air tubing since hole is drilled already in this room but I will put rigid elbows? Will that make a difference

      1. Expert Member
        Akos | | #26

        To stay under the 0.4" WG pressure limit you need to fix your ducting. Assuming hard pipe you only have about 110' of equivalent length to work with. That might sound like a lot but a 90 deg metal adjustable elbow is equivalent to 35', so bends quickly add up.

        First you want to fix the outside runs. Make sure the flapper from the vent hood is removed both for intake and exhaust. This should get the vent cap down to about 25' equivalent length.

        From there run semi rigid aluminum duct (stuff the looks like dryer vent pipe but bigger) from the wall hood to the unit. This is much less restrictive than plastic flex duct and easier to work with than hard pipe. You can reuse the insulation sock of the flex pipe right over the aluminum one. Make sure to keep the plastic vapor barrier sleeve on the outside this is needed to prevent condensation. I'm guessing that will use up about 20' of equivalent length.

        That leaves you 65' for the house. This means you need to upsize a bit.

        Put a 6 to 8" adapter on the unit and run 8" flex to the first split for the fresh air. You can go smaller if you skip flex and use 7" semi rigid aluminum. The interior runs don't need to be insulated.

        For the stale air pickup, install a 6"x6"x5" T right on the unit. Leave the 5" port open as the basement stale air pickup and connect the 6" flex run from the rest of the house to the 6" port.

        That should get you into the ballpark but I would still pick up a good differential manometer and check pressure drops and airflow balance across the core.

  21. DennisWood | | #27

    Good point on the hood Akos. The intake flap should already be removed I’m guessing from your previous install, but the exhaust flap may still be there and it’s very easy for it to get stuck or frozen partially open. Just remove it as your ERV has dampers for both OA and EA.

    1. Shawnnixon1 | | #28

      So i did remove for intake but not exaust I will remove that, Akos what you meantioned sounds really good.

      Right now I have a duct for fresh air intake as u can see in the pic coming to the air exchanger (note pic was taken before it was ziptied to the top wood so looks slanted.

      2 more questions sorry!

      1.If u look at the other pic notice all 3 duct going to the other room with bends on the wall to the other side of the wall then upwards.

      The fresh air intake since this is going to have a bend no matter what to bring to the other room and the rest of the ducts will go straight up (assuming this will make a huge difference?) What is the best way for that fresh air intake duct? Should I do Rigid? Or flex then elbow and then flex to the other room and then another elbow to connect it downward to the erv?

      2. The ducts are going above which is my laundry room and in that room the supply has a split, one on the wall of laundry which is the main floor blowing air and the split and other duct is going above that to my walk in closet and straight to attic, in the attic theres a split connecting to basement an existing old duct that was already there since house was built 6”then to one of the rooms and then going down a walk in closet (10-14 feet away) from the main point of entry to attic, to main floor, all 3 is a return exhaust where its sucking in air (opposite of the supply where laundry room is). The other duct that was going to attic is going maybe 9 feet away which is middle of all 3 rooms and blowing fresh air. Assuming in the attic the ducts are not longer than 14 feet (air connecter duct) and everything else in the house will be rigid, is it ok? And do I still need to do the T on the machine if theres already a connecting in the attic connecting to basement.

      This is how my set up is if you can help me with those 2 questions that will be great. If its easier I can take a video upload on youtube

  22. DennisWood | | #29

    Shawn, draw a simple sketch of your setup and attach it to a post. Include the existing lengths and sizes of duct. I'm sure folks will be able to follow along much better this way.

    1. Shawnnixon1 | | #30

      I will do that thanks!

  23. Shawnnixon1 | | #31

    I tried to remove the vent cap on the exhaust vent outside but doesnt seem easy since the entire thing is siliconed and cant remove it by stick my hand in…i will remove the silicone next week and then take it.

    I did see that the cap is only halfway open for the amount of air its pushing out, for now i put double side tape on top of the cap and sticked it to the top of the vent so its more open….what difference does it make by removing it if it only opens for the amount of air it pushes out?

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