Page 4 of 4 FirstFirst 1234
Results 40 to 52 of 52
  1. #40
    Join Date
    Jun 2008
    Posts
    128
    Personally, I think that if you are going to exhaust, you should exhaust... Our master bath has a 180CFM fan near the shower/tub and a 50 CFM fan in the "WC". The other 3 bathrooms have 80 CFM fans with motion sensors/timers.

    I'm finding that I need better mixing of internal air at night. Bedrooms have elevated CO2, rest of the house is minimal. The ERV is relayed to the zone control so it circulates air to all zones when running. Seems like I need more AH fan, not necessarily more ERV time. Wondering if moving the ERV to "low" speed and increasing the run time percentage would help, but then run the risk of more ERV time without Y1 to remove humidity... Oh the agony of finding balance...

  2. #41
    Join Date
    Jun 2008
    Posts
    128
    Quote Originally Posted by Carnak View Post
    Right now I have no ERV, I have very humid outside air, more humid than the vast majority of posters in here, going to my cooling coil right now. It can take more moisture, I can obviously add a lot more fresh air given my homes present affinity for low humidity.

    The house cannot take stupidly pumping in untreated fresh air around the clock. That is why I advocate ventialting at high rates intermittently and conditioning it first.

    The reason it works is I do not have to worry about infiltration.
    This is one of the reasons I like the VP IAQ. It *attempts* to satisfy vent requirements during cooling/dehum runs first, and then only runs without Y1 if required to meet minimum vent settings.

  3. #42
    Join Date
    Apr 2002
    Posts
    11,808
    Well since you have the full nine yards with the dehumdifier, the cadallac solution would be to duct fresh air from the ERV directly to the bedrooms, then say one supply in an open common area.

    Bedrooms do tend to build up the CO2 quickly and when you are fortunate to be active, the levels build up higher. My master bedroom has two outside walls, south and west and is not overly huge, so it has a failry high CFm per unit volume and the air turns over quick less than 7 minutes when the cooling cycles on.

    If I am in the living room and my wife in bed reading, you can watch the CO2 levels jump up a few points every timne the cooling kicks on as it purges it out of the bedroom.

    The strictest residential ventilation codes in the world have 20 CFM going to a master bedroom so following said code your indoor levels will rise.

    A lot of data presented on this forum shows that bedroom CO2 levels are the lowest when you run your air handler fan all the time, and the effect is more profound than running a ventialtion fan to pump fresh air into a home.

    CO2 itself is not going to hurt you. It merely gives an indication of how much fresh air you get. Supposedly when the indoor CO2 is about 678 PPM higher than outside and this number gets rounded up to 700, they say you are receiving enough air to purge 'bio-effluents' so that the place does not smell like a monkey den.

    If you foolishly built your home out of poisonous materials then you will need more fresh air to try and dilute the poison.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  4. #43
    Join Date
    Apr 2002
    Posts
    11,808
    there are numerous timers out there, aircycler and others that try and give you your air changes

    You can count on one hand and have fingers to spare on how many days a year my cooling system never runs.

    I am moving towards intermittently ventilating at about triple the ASHRAE 'continuous rate'

    I am going to add a CO2 sensor as a test but right now I feel it will not run the system much. I have a device that functions as an event logger, can tell when up to four systems run
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  5. #44
    Join Date
    Jun 2008
    Posts
    128
    Quote Originally Posted by Carnak View Post
    Well since you have the full nine yards with the dehumdifier, the cadallac solution would be to duct fresh air from the ERV directly to the bedrooms, then say one supply in an open common area.
    I don't have a whole house dehumidifier, only the dehum cycle built into the Arzel HPP zone panel.

    I'm trying to piece together a time of day based relay system that will only open my bedroom zones from 9pm-5am for ERV calls, and then open all zones (or maybe just the central zone) during the day.

  6. #45
    Join Date
    Apr 2002
    Posts
    11,808
    Quote Originally Posted by patchesj View Post
    Personally, I think that if you are going to exhaust, you should exhaust... Our master bath has a 180CFM fan near the shower/tub and a 50 CFM fan in the "WC". The other 3 bathrooms have 80 CFM fans with motion sensors/timers.

    I'm finding that I need better mixing of internal air at night. Bedrooms have elevated CO2, rest of the house is minimal. The ERV is relayed to the zone control so it circulates air to all zones when running. Seems like I need more AH fan, not necessarily more ERV time. Wondering if moving the ERV to "low" speed and increasing the run time percentage would help, but then run the risk of more ERV time without Y1 to remove humidity... Oh the agony of finding balance...
    You must have a large master bath. I am doing a substantial home right now with the vrv system.

    I am using an ERV on the master bath to draw about 200 CFM exhaust, all the time. I am going to over load it and bring in 300 CFM of fresh air.

    This fresh air from the ERV is going to get mixed with some return air from the central core and then cooled by a unico high velocity air handler. Going to run the unico small supplies to a guest bedroom, three regular bedrooms and then a couple to the master suite. Be some supply air to a big 'grand hotel stair case in the central core, and then a supply down to the basement.

    The supplies will be more than 50% fresh air.

    Will be like a 2 ton first stage cooling system to a 12,000 square foot place.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  7. #46
    Join Date
    Jun 2008
    Posts
    128
    M Bath is about 170 sq ft, WC is about 20.

  8. #47
    Join Date
    Apr 2002
    Posts
    11,808
    A cfm per square foot is pretty decent exhaust from a residential bathroom, sometimes with the master suites you can get away with a little less, but need something over the whirlpool, the WC and in the shower to capture
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  9. #48
    Join Date
    Jun 2008
    Posts
    128
    Quote Originally Posted by Carnak View Post
    A cfm per square foot is pretty decent exhaust from a residential bathroom, sometimes with the master suites you can get away with a little less, but need something over the whirlpool, the WC and in the shower to capture
    The fan is located between the heated corner tub (I think it's about 180 gallons) and the shower (has sprays and water from multiple walls). I hate steamy bathrooms. I want to be able to shut off the fan when I leave and not worry about residual humidity. We used the Panasonic DC fans everywhere. Love them.

  10. #49
    Join Date
    Apr 2002
    Posts
    11,808
    My ERV will get interlocked with my compressor in that when the compressor is running the ERV runs. Not vice versa, meaning the ERV will not force on the compressor.

    I will have the wall switch for the existing fans turn it on as well. The CO2 sensor will just jump the same contact I will use for the wall switch start.

    I have a fire lite fire alarm panel housing to house what I wire up for this. If i was more of an electronics geek, it would all be on a little circuit board.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  11. #50
    Join Date
    Apr 2002
    Posts
    11,808
    do you have a range hood and or central vac ducted outside?

    just asking as numerous substantial bath fans, a clothes dryer and a range hood, sort of factor in on the total air changes. Especially the dryer.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  12. #51
    Join Date
    Jun 2008
    Posts
    128
    Quote Originally Posted by Carnak View Post
    do you have a range hood and or central vac ducted outside?

    just asking as numerous substantial bath fans, a clothes dryer and a range hood, sort of factor in on the total air changes. Especially the dryer.
    Yes and Yes. I think the percentage of run time for the range hood/central vac/dryer are fairly minimal. Certainly when compared to the ERV run time. I haven't taken CO2 measurements while either was running, I'm sure it has a big short term impact on ACH but averaged out over the week probably not much.

  13. #52
    Join Date
    Jun 2008
    Posts
    128
    This is an old thread, but I wanted to update with some new data. I had a blower door test done today. Came back with readings between 2000 and 2300 cfm @ -50. The meter was reading "Lo" for a while and the guy actually turned it off, reset everything and then turned it back on because he thought it had to be an error. Seems like those numbers actually fit into the guestimates made 3 years ago, so I think they might be close.


Page 4 of 4 FirstFirst 1234

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event