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  1. #14
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,399
    I will never own a gas range, ventless gas logs or ventless gas space heater. I can't believe they are even legal it's ridiculous, especially in a tight home you are asking for trouble IMO

  2. #15
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,139
    for most problems there is a solution. it is reasonable to keep a level head
    and figure it out rather than scare yourself or someone else.

    ventless fireplaces have make up air provisions.
    the problem is that these provisions are not followed with
    ventless fp is installed.

    same for stove vents. personally I don't see the need for viking ranges
    with 10 burners & huge stove vents. unless you do catering or run a
    soup kitchen..
    even so, there are provisions for these grossly oversized stove hoods.
    the directions for the make up air just have to be followed.

    4 burner stove with 600 cfm vent hood..that is sized right.
    it is the 1200 cfm hoods that cause problems.

    as your home is being constructed, you have the chance to see to the
    details that often get overlooked. use this wisely and focus on things
    that won't as easily be addressed at the end of the project.

    teddybear is one cool headed guy. his information is solid IMO.

    in the post on the other forum, you described your insulation package.
    could you share that info here also?

    house is just getting to blacked in stages. the information OP gets
    here will be achievable in a timely manner.

    before going off on a tanget, lets answer the questions OP has.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  3. #16
    Join Date
    Oct 2012
    Posts
    91
    Thanks all for your continued feedback & expert ops!

    Quote Originally Posted by teddy bear View Post
    I must appologize! This old bear missed your post and thanks for the support from my follow posters.
    Glad you are considering fresh air ventilation and humidity control. In moderate climates like yours, I suggest that a whole house ventilating dehumidifier will handle fresh air ventilation and maintain <50%RH when there is low/no cooling loads. 100 cfm of make-up fresh air ventilation is adequate for changing the air in your home in 4-5 hours. The fresh air ventilation is needed when the home is occupied and winds are calm.
    During cold windy weather most well built homes do not need supplemental fresh air ventilation. This is because the natural forces on the home will change the air in the home every 4-5 hours.
    The kitchen hood is a wild card. I suggest not using high speed exhaust unless you open a window or a dedicated make-up system. There are a few hoods that include make-up air as part of the design.
    Sorry about the mess-up on catching your original post.
    Regards TB

    Per the prompt from energy_rater & would like to get some feedback from every1 & Teddy Bear on if the cost of a central dehumidifier can be alleviated by using in lieu a couple of stand-alone DH's & circulating air via a HVAC attenuated damper?

    Basing my question on these 2 white papers:
    http://www.buildingscience.com/docum...search-results
    http://www.buildingscience.com/docum...ntrolling-cost

    Insulation are as follows:

    1) Attic's roof plane will be sprayed foamed.
    2) On top of ceiling in all other areas - Loose filled cellulose
    3) Walls - Dense Packed Cellulose
    4) Crawl space - 6mm Poly Vapor barrier on floor & sealed to walls.
    4a) Foundation wall - R10 XPS insulation or equivalent on this
    4b) Sill plate - foam sill sealer
    4c) Rim joist - spray foam
    5) Air sealing details will be applied in all other fine areas

  4. #17
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,139
    1) Attic's roof plane will be sprayed foamed.
    2) On top of ceiling in all other areas - Loose filled cellulose


    these items will be explained as soon as OP meets with builder this weekend.
    just fyi
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  5. #18
    Join Date
    Oct 2012
    Posts
    91
    Quote Originally Posted by energy_rater_La View Post
    1) Attic's roof plane will be sprayed foamed.
    2) On top of ceiling in all other areas - Loose filled cellulose


    these items will be explained as soon as OP meets with builder this weekend.
    just fyi
    So spoke to my builder & got some more info:

    Our house is 1.5 Stories in the first 1/3 of the house front & a rancher in the back.

    So the 1.5 story structure is foamed no cellulose at the roof line unvented HOWEVER, the "ranch roof" is vented, cellulose + not foam at ceiling plane

    So what do you think energy_rater?

  6. #19
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,261
    Quote Originally Posted by Ben44 View Post
    Thanks all for your continued feedback & expert ops!




    Per the prompt from energy_rater & would like to get some feedback from every1 & Teddy Bear on if the cost of a central dehumidifier can be alleviated by using in lieu a couple of stand-alone DH's & circulating air via a HVAC attenuated damper?
    areas
    Getting fresh clean air into a home is important. Keeping the home <50%RH is equally as important. Mechanics are upto you and your ability to manage them. Efficiency and durability of the devices varies. Units like the Ultra-Aire are more expensive than a couple of residental dehus with an air damper connected to a controller using the air handler blower. These devices operated 27/7 on some on/off cycle. The residential dehu are inefficient and not reliable long term. Short term, this type of system will work, but needs close monitoring.
    While the Ultra-Aire are high efficiency and durable. The ventilation timers and %RH controller are the best.

    You get what you pay for. If you can afford the UA, get it. If on a budget, do the best that you can.
    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"

  7. #20
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,139
    1/3 foam insulate unvented attic
    2/3 cellulose vented attic

    why?

    pick one or the other.

    with foam you'll air seal, put ducts in semi conditioned space &
    air communication between attic & living space isn't a concern

    with cellulose what you save on insulation costs
    you'll spend in trying to seal the air leakage between attic & living space.

    cellulose is a dusty product. the small particles enter the house through
    tiny leakage areas. while it does insulate, it does nothing to air seal.
    insulation without air sealing is a wasted effort.

    efficiency costs are always upfront. benefits are longterm.
    not a lot of room for negotation.

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

  8. #21
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,261
    Quote Originally Posted by Ben44 View Post
    Oooh - might have to research on your Trane statement. Do you think in a 'tight' house that humidity would be an issue?

    Can a centralize ERV's serve as a replacement for bathroom exhausting? Or would I still need indv. bathroom exhausts?



    To tell you the truth, these large hoods are starting to be more costly than their worth with all these 'add-ons'. We are erring on the side of conventional wisdom which says to provide x CFM's (8" duct btw) to cover a 30" 4-burner gas range. Even though we will NEVER have all 4 burners lit up MAX @ any one time.

    We are sensitive to smells, so minimizing the smell is a primary concern but reading has lead us to believe that we will have to add in MUA, Recovery Ventilators, & Dehumidifiers because we essentially are sucking out air & have to introduce air again into the envelope.

    Sorry to whine, I guess we never knew it can be so complicated & costly to breath! LOL!
    A few more comments on the suggestions for ventilation in your home. 200 cfm of real exhaust for range will cover oven/4 burner use. Install 300 cfm design will get you 200 cfm. Consider that you have a clothes drier, bath fans, and possible central vac. All need make-up air to function.
    During cold windy weather in your climate, typical air tight home will have a natural air change in 5 hours. This could be up to 200 cfm of infiltration/exfiltration. Operating any of the exhaust equipment will change the natural flow. Infiltration increases, while exfiltration decreases.
    During calm winds, moderate temps, natural delines to near zero and exhausting air will function while causing negative pressure. Any open gravity chimineis have great potiential for backdrafting. Avoid all gravity chiminey. Other than backdrafting, negative pressure is not a bad thing. During wind and stack effect, negative pressure can not be avoided.
    Because ERVs require balance in/out air flow devices and that you have significant natural ventilation during cold weather, I suggest very little benefit for the investment.
    Minimal make-up air ventilation during the cold windy months recommend. I would limit make-up air to normal times of occupancy and signs of excess moisture in the home.
    During warm calm weather, you need mechanical make-up fresh air at a minimum when the home is occupied. Dehumidification will be needed when the outdoor dew points are +55^F and there is low/no cooling loads.
    No ERV because of very low payback the need for make-up air for exhaust devices during normal occupancy. A whole house ventilating dehumidifier is suggested to provide make-up air on a occupancy schedule and maintain <50%RH. You may also need a humidifier depending on the number of occupants and ativities during low outdoor dew points and the amount air movement through the home. With a whole house dehumidifier, a simple properly set up a/c is adequate to maintain <50%RH. VS blower are nice but not a must. A good Merv 11 air filter for the ventilation and air handler are also important to keep the equipment clean.
    Keep us posted on your progress.
    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. #22
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,700
    Ideally your pressure is from dry to wet.

    So if you have humid indoor spaces in winter, having those spaces be negative helps avoid moist leaving air contacting cold surfaces. (rotted roof syndrome)

    In summer/ac dominant climates a little positive can prevent continuously pulling warm moist entering air in across cold surfaces. (moldy ceiling perimeter or register issues)
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  10. #23
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,261
    Quote Originally Posted by tedkidd View Post
    Ideally your pressure is from dry to wet.

    So if you have humid indoor spaces in winter, having those spaces be negative helps avoid moist leaving air contacting cold surfaces. (rotted roof syndrome)

    In summer/ac dominant climates a little positive can prevent continuously pulling warm moist entering air in across cold surfaces. (moldy ceiling perimeter or register issues)
    Technically, you are right. But during cold weather, the upper part of the home is under a positive pressure regardless of the ventilation system. This forces warm moist air up through the attic. ERV, make-up air, or with exhaust ventilation, a small amount of moist air leaves via the ceiling. The key is to have a moderately low dew point in the exfiltration air to avoid condensation on the cold surfaces. The wet roof deck is because the air leaving the home is excessively wet like +40^F dew point. Poolrooms in cold climates are examples of the need for a tight structure with enough exhaust to stop most of the exfiltration of high moisture out through the insulation of the upper part of the structure.

    I had a high occupancy home in WI with severe frost on the roof deck. When the warm weather hit, moisture ran down the outside siding. Moisture on the windows also. The furnace was gravity chiminey.
    There 8 occupants with summer moisture problems also.
    The home was .1 ach home and the clothes drier/kitchen hood backdrafted the furnace. Adding 150 cfm of make-up air dried the home down to 32^F and the attic dried. Of course, we did it with a whole house ventilating dehumidifier. The dehumidifier only ran when the outdoor dew point was +55^F. Of course a ERV would have dried down the home but not solved the backdrafting problem. They need the simplest low cost fix possible.
    This makes the point that moderately moisture levels can leave the attic dry. High dew point air will make a cold attic wet. Confusing?
    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. #24
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,700
    Nice post,

    Connecting the remaining dots - TB has just expressed the tremendous importance of sealing penetrations that allow stack induced leakage. This is easiest accomplished BEFORE adding copious amounts of porous insulation to your attic.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  12. #25
    Join Date
    Apr 2001
    Location
    Over Here
    Posts
    1,105
    Quote Originally Posted by teddy bear View Post
    The dehumidifier only ran when the outdoor dew point was +55^F.
    TB, this statement caught my eye. Could you elaborate on the control that was used.... or was this manually done?

  13. #26
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,261
    Quote Originally Posted by thermojohn View Post
    TB, this statement caught my eye. Could you elaborate on the control that was used.... or was this manually done?
    You set the dehumidistat that controls the dehumidifier inside the home at 50%RH. When the a/c runs enough to maintain <50%RH, no dehumidification needed. When the outdoor dew point is high, the indoor %RH rises, dehumidifier runs.
    If the a/c runs enough, the indoor %RH will be <50%rh. No dehumidification is needed.
    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"

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