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  1. #14
    Join Date
    Mar 2013
    Posts
    112
    Thanks

    One of th quotes I have for a heat pump has the HRV install included. I think they run the HRV supply and return to the HVAC return and run the airhandler continuous. The HRV will somewhat temper the incoming cool air but the BTU's /hr needed to heat the fresh air at 0 is ~ 3000btus. From what I have read the HRV's do dehumidify the incoming air and you can set them to the amount of humidity you require.
    Last edited by JimmyP; 04-22-2013 at 04:19 PM. Reason: spelling

  2. #15
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Quote Originally Posted by JimmyP View Post
    Attachment 376341here is a table of average RH for the year
    If you want to maintain <50%RH, you need supplemental dehumidification. As your average chart shows, the average is a little high. To get a high average, you need higher and lower moisture levels. During the days/weeks of high humidity, you will be damp inside. An erv/hrv does not remove moisture in the home during outside high moisture conditions. This why they call outside conditions "weather". Its dry, its wet, and it is just right. The "Whims of Weather" have some wet springs, summers, and fall. You need supplemental dehumidification. Add the moisture from the occupants and their activities, you have 2-4 lb. per hour dehumidifier load during the damp times of the year.
    Going with a hrv/erv, gives you a home that is barely ok during average weather conditions. While a whole house dehumidifier with the ventilating option provide the need fresh filtered air when needed and maintains <50%RH during the seasonal wet extremes. Being able to provide fresh air for indoor air quality, and (<50%RH) for comfort during the wet "Whims of Weather" should be an important part of a quality system. So, HRV/ERVs needs supplemental dehumidification also. If your home is not wet during cold windy weather, an HRV will not save enough to warrant the investment. Also remember that your home needs make-up air for the clothes drier and other exhaust devices.
    Regards TB
    Last edited by teddy bear; 04-23-2013 at 07:19 AM. Reason: change phrases
    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"

  3. #16
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,163
    "It there some way to tell if I am getting enough fresh air without adding ventilation without a blower door test?"

    Teddy bear has a methond of determining fresh air changes per hour based
    on CO monitering.

    when determining how tight a house is you have to have some actual
    basis..rather than just a wag or assumption.

    it is amazing that you would spend a good chunk of $$ on erv..or hrv..whichever
    hasn't been determined..but not a small $$ amount to understand what you need
    hrv/erv to achieve.
    sounds to me that the company selling you this equipment has not
    explained it well to you.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  4. #17
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Quote Originally Posted by energy_rater_La View Post
    "It there some way to tell if I am getting enough fresh air without adding ventilation without a blower door test?"

    Teddy bear has a methond of determining fresh air changes per hour based
    on CO monitering.

    when determining how tight a house is you have to have some actual
    basis..rather than just a wag or assumption.

    best of luck.
    Attaching a data graph showing the CO2 levels, inside/outside dew points, and outside temp. This home is a .2 ach at average WI winter temp and winds. So not fresh air ventilation needed at the colder windy WI weather. By the middle of April, as the outdoor temps rise, the natural infiltration has declined to about .1 ACH per hour or about 50 cfm. On calm moderate days, the natural infiltration declines to near zero. This homes needs mechanical fresh air during calm, moderate temps.
    The indoor dew points are higher than the outside. As the outdoor dew points rise to +55^F, dehumidification is needed to maintain <50%RH. An ERV/HRV will not solve this problem. A whole house dehumidifier with the filtered,fresh, make-up air ventilation option is ideal.
    Regards TB

    Dew Point CO2 data
    WI 4 15 13 Dew Point Data .pdf
    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. #18
    Join Date
    Mar 2013
    Posts
    112
    Quote Originally Posted by energy_rater_La View Post
    "It there some way to tell if I am getting enough fresh air without adding ventilation without a blower door test?"

    Teddy bear has a methond of determining fresh air changes per hour based
    on CO monitering.

    when determining how tight a house is you have to have some actual
    basis..rather than just a wag or assumption.

    it is amazing that you would spend a good chunk of $$ on erv..or hrv..whichever
    hasn't been determined..but not a small $$ amount to understand what you need
    hrv/erv to achieve.
    sounds to me that the company selling you this equipment has not
    explained it well to you.

    best of luck.
    They are required by code here in Canada.

  6. #19
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    WI indoor outdoor dew points CO2 ppm .pdf
    Quote Originally Posted by JimmyP View Post
    They are required by code here in Canada.
    They tell me that fresh air ventilation not necessarily HRV are required in CA. But whatever. I need an excuse to show additional data on the graph of the outdoor dew/inside dew point. The additional information shows the average outdoor/indoor point to make the point of the increased moisture levels caused by the occupants. This home has a 50-60 cfm natural infiltration during mild winter conditions which is .1 air change per hour. Yet the home shows +.2 ACH during average winter weather. The average outside dew point is 29^F for the week. The average inside dp is 45. The occupant contribute about 1 lb. of moistue per hour of occupancy.
    As the outdoor dew point rises and the outside temps rise, the natural fresh air change declines and the inside dew dew point will rise. All of this increases the need of a dehumidifier.
    The best for you is too track the outside/inside dew points and keep us posted.
    Increase the fresh air ventilation as the weather becomes more moderate. Track the %RH in the lower levels of the home. When the %RH rises above 55%RH, operate your dehumidifier.
    REgards TB

    Outside inside dew points and averages
    WI indoor outdoor dew points CO2 ppm .pdf
    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"

  7. #20
    Join Date
    Mar 2013
    Posts
    112
    Thanks teddy bear.
    Sorry , I thought it had to be a HRV. So any kind of mechanical ventilation woud do then. Does that include the Range hood fans and bathroom fans. Would it be best to hook up a whole house dehumidifier into the HVAC ducting like they do with the HRV? Can you, or is it better to have both?

  8. #21
    Join Date
    Mar 2013
    Posts
    112
    Name:  Dew Point average.jpg
Views: 35
Size:  90.1 KBName:  Temperature average.jpg
Views: 35
Size:  90.9 KB

    TeddyBear
    I am attaching the average dew point and average temperature. Could you tell from this what size of a dehumidifier I would need?

    Thanks
    Attached Images Attached Images  

  9. #22
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    How many occupants? How many cfm of fresh air? Suggest 50%RH as objective during the high outdoor dew points. Also suggest a fresh air change in 5 hours. Also the a/c should be setup with a 45-50^F coil temp to assist in humidity control.
    Look forward to the your specs.
    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"

  10. #23
    Join Date
    Mar 2013
    Posts
    112
    teddy bear
    There are just 2 of us 85% of the time. 12500cuft of air volume and a change every 5 hours would be 72 cfm. I don't know how often the a/c will be running as it doesn't get very hot although with all the windows it can get quite warm. So do I ask the tech's to adjust the coil temp to 45 to 50 while they are installing it, or do I do that?

    Jimmy

  11. #24
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Quote Originally Posted by JimmyP View Post
    teddy bear
    There are just 2 of us 85% of the time. 12500cuft of air volume and a change every 5 hours would be 72 cfm. I don't know how often the a/c will be running as it doesn't get very hot although with all the windows it can get quite warm. So do I ask the tech's to adjust the coil temp to 45 to 50 while they are installing it, or do I do that?

    Jimmy
    Installer set the air flow to get the coil temp. Does the 12,500 ft^3 include the basement? 12,500 cuft in 5 hours is 42 cfm. The moisture in 42 cfm at your max of 23^C dew point dried down to 23^C, 50%RH,13^C dew point is 2lbs./pints per hour. The occupants may contribute upto 1 lbs. per hour. This is about 3 lbs. per hour. A 70 pint per day quality dehumidifier should work. The Ultra-Aire 70H whole house dehu is a good canidate. With the filtered make-up air option and the DEH Controller, you would have filtered fresh air ventilation when occupied and <50%RH during all weather conditions. During peak cooling loads, the dehu will not operate. Only supply fresh filtered air. When you are away, the dehu will maintain <50%RH without any cooling load.
    Keep us posted.
    Regards TB
    A small blurb.
    http://www.youtube.com/watch?v=4vnl2Se2g70
    Last edited by teddy bear; 04-26-2013 at 11:47 AM. Reason: update
    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"

  12. #25
    Join Date
    Mar 2013
    Posts
    112
    Teddy bear

    Thanks for that info. I made a typo it should be 21500 and yes it includes the basement. Will I still need a HRV or ERV with this? Should I tie it into the HVAC or have it seperate?

  13. #26
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,163
    nice video Teddy Bear, had me checking out the switches on my 70H.

    is that you in the video?
    The cure of the part should not be attempted without the cure of the whole. ~Plato

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