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  1. #1
    Join Date
    Jun 2007
    Location
    Bucks Co PA
    Posts
    364

    House Dehu- Fresh Air- Heat Recovery?

    I'm coveting a two stage heat pump, but the wife sees too many $$$. (styling is more important to her than function)

    My main problem is humidity 60 to 75%.

    Therefore, I'm looking at a Ultra-Aire whole house Dehu until I can persuade the wife a new heat pump is desirable. (BTW Ultra-Aire sent a list of dealers most of which are far away). I figure a whole house Dehu will give comfort and reduce the need for AC till it gets hotter.

    My question, I hear so much about indoor pollution and I read that the Ultra-Aire can be vented from outdoors, but won't that increase operating costs by bringing in outdoor humidity ?

    I also read on this forum, that CO2 can be an indication of indoor pollution. Do most HVAC techs have a device to read CO2 ? I know they are expensive devices.


    BTW Anyone see many heat recovery units with out door ventilation ?
    .

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,359
    your local a/c contractor is a good canidate to install the Ultra-Aire in your home. UA is simple for knowledgable contractor. Most UA dealers have been introduced to the unit via inovative customers.
    Despite what you read, full featured a/c/hp will not control humidity during low/no cooling loads and high humidity. If you are getting adequate fresh air into your home, you need 20-60 lbs. per day of dehumidification to maintain <50%RH in your home. On a hot day, your a/c will remove this moisture. Fresh air is getting into your home naturally on windy days. Infiltration is one of the reasons your humidity maybe high now. A home should be tight enough to avoid excess infiltration during cold weather and be short on fresh air during summer. Very tight homes need the ventilating feature. If your home is a leaker, no need for fresh air from your UA. Just use it as a whole house dehumidifier. Homes that need humdification during cold weather are leakers. The should be tighten to the point where no humidification is required. That will save big bucks on heating. But you will need supplemental ventilation during milder temperatures. Not all bad. An air tight home is net energy gain with winter gains. Search "teddy bear" post for additional info. 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"

  3. #3
    Join Date
    Jun 2007
    Location
    Bucks Co PA
    Posts
    364
    Quote Originally Posted by teddy bear View Post
    your local a/c contractor is a good canidate to install the Ultra-Aire in your home. UA is simple for knowledgable contractor. Most UA dealers have been introduced to the unit via inovative customers.
    Despite what you read, full featured a/c/hp will not control humidity during low/no cooling loads and high humidity. If you are getting adequate fresh air into your home, you need 20-60 lbs. per day of dehumidification to maintain <50%RH in your home. On a hot day, your a/c will remove this moisture. Fresh air is getting into your home naturally on windy days. Infiltration is one of the reasons your humidity maybe high now. A home should be tight enough to avoid excess infiltration during cold weather and be short on fresh air during summer. Very tight homes need the ventilating feature. If your home is a leaker, no need for fresh air from your UA. Just use it as a whole house dehumidifier. Homes that need humdification during cold weather are leakers. The should be tighten to the point where no humidification is required. That will save big bucks on heating. But you will need supplemental ventilation during milder temperatures. Not all bad. An air tight home is net energy gain with winter gains. Search "teddy bear" post for additional info. Regards TB
    Thanks for the reply TB.
    My house was built in 1988, and I had a "energy" company seal the house as it was built and added insulation to the walls which are about R-20-22. Attic is about R-38.

    It is 2600 sq ft, and I do need humidification in the winter, but I do not need to start the furnace till <52* OD unless it is very windy. The high humidity and relative low heat loss leads me to believe it is tight, but humidity is needed in winter.

    I have a HVAC contractor referred to me by someone on this board, but when I called to ask about the Ultra-Aire a girl answering the phone said they only sell April Aire and gave me a "humidifier" model. Maybe I should call back and ask for the owner.


    BTW, will the average HVAC tech have access to a CO2 measuring device ?
    .

  4. #4
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,359
    Yes, talk to the owner. Or there is a bright, energitic a/c contractor near you who is looking an opportunity to serve. As you see by the discussions on this site, traditions are hard to break. 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"

  5. #5
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    If you want to persuade the contractor that Aprilaire is not your preference, tell them about the wattage vs. pints/day difference. As I remember the UA-100 series is rated around 100 pints/day and draws about 7 amps. And the newer UA-XT150H is rated around 150 pints/day and also draws about 7 amps. There are some intermediate Thermastor models which are not equally energy efficient. Last time I looked, Aprilaire had one model rated around 90 pints/day and drawing about 10 amps.

    I am ga-ga about being efficient in certain ways, to the point of being emotional not rational, this energy efficiency really pushes my hot button personally. But if you choose to be rational, you ought to estimate the actual cost of running and if Aprilaire is any cheaper, see what the payback time is.

    You might be able to persuade your wife via 1st trying a cheaper dehu bought from a big box store. If she sees that is *somewhat* effective in making the home more comfortable, then you can sell the idea of a bigger, better and less energy intensive version of that benefit. I accidentally did this experiment with my own family, my wife surprisingly really likes the benefit of a Thermastor Santa Fe RX in the laundry room.

    >>Ultra-Aire can be vented from outdoors, but won't that increase operating costs by bringing in outdoor humidity ?

    Think you can count on the UA to do its work on outdoor air, so you cannot really say it brings in outdoor humidity. What it intakes is outdoor humid air (if you ventilate) and what it delivers is dry air. There is an energy cost associated with this benefit. Try looking at it this way: it would be even more energy efficient to turn off the AC entirely and open the windows, but that's not quality of life according to most people.

    >>I also read on this forum, that CO2 can be an indication of indoor pollution.
    >>Do most HVAC techs have a device to read CO2 ? I know they are expensive devices.

    I am a homeowner in S.Texas which is far from you, but around here most HVAC techs can be counted on to have a truck and some basic tools and knowledge. I find that if I ask one to measure static pressure, he likely will tell me he doesn't have the Magnahelic gauge to do that. A CO2 measuring device is far more exotic than that.

    >>BTW Anyone see many heat recovery units with out door ventilation ?

    Any HRV or ERV would qualify for that. Can you answer whether many of your neighbors have an HRV or ERV? They sell quite a few for use *somewhere* in the country.

    Hope this helps -- Pstu

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    With your indoor humidity ,you have an issue of somekind.

    Maybe infiltration ,but sounds like it was built tight.

    Rain and overcast here,the wife cooking and the humidity has crept up to 52&#37; on the sysstem that serves the kicthen,the other one is at 48%.Carrier Infinty on one and Thermidistat on the other.

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,359
    your local a/c contractor is a good canidate to install the Ultra-Aire in your home. UA is simple for knowledgable contractor. Most UA dealers have been introduced to the unit via inovative customers.
    Despite what you read, full featured a/c/hp will not control humidity during low/no cooling loads and high humidity. If you are getting adequate fresh air into your home, you need 20-60 lbs. per day of dehumidification to maintain <50%RH in your home. On a hot day, your a/c will remove this moisture. Fresh air is getting into your home naturally on windy days. Infiltration is one of the reasons your humidity maybe high now. A home should be tight enough to avoid excess infiltration during cold weather and be short on fresh air during summer. Very tight homes need the ventilating feature. If your home is a leaker, no need for fresh air from your UA. Just use it as a whole house dehumidifier. Homes that need humdification during cold weather are leakers. The should be tighten to the point where no humidification is required. That will save big bucks on heating. But you will need supplemental ventilation during milder temperatures. Not all bad. An air tight home is net energy gain with winter gains. Search "teddy bear" posts for additional discussion. 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"

  8. #8
    Join Date
    Apr 2002
    Posts
    11,808
    Quote Originally Posted by Jack2007 View Post
    I'm coveting a two stage heat pump, but the wife sees too many $$$. (styling is more important to her than function)

    My main problem is humidity 60 to 75%.

    Therefore, I'm looking at a Ultra-Aire whole house Dehu until I can persuade the wife a new heat pump is desirable. (BTW Ultra-Aire sent a list of dealers most of which are far away). I figure a whole house Dehu will give comfort and reduce the need for AC till it gets hotter.

    My question, I hear so much about indoor pollution and I read that the Ultra-Aire can be vented from outdoors, but won't that increase operating costs by bringing in outdoor humidity ?

    I also read on this forum, that CO2 can be an indication of indoor pollution. Do most HVAC techs have a device to read CO2 ? I know they are expensive devices.


    BTW Anyone see many heat recovery units with out door ventilation ?
    .

    I have been yapping about CO2 sensors but I do not think the typical tech will have one.

    It sounds like you do not have AC at present is this the case?

    A small dehu in the basement will make a difference. I used to circulate basement air in my old home in Canada through out the house during the summer. I ran a Kenmore 40 pint dehumidifier down there, it kept the huimidity under 60%. Keeping the windows closed and the drapes drawn during the day kept the heat out, so it was bearable without central AC

  9. #9
    Join Date
    Jun 2007
    Location
    Bucks Co PA
    Posts
    364
    Quote Originally Posted by Carnak View Post
    I have been yapping about CO2 sensors but I do not think the typical tech will have one.

    It sounds like you do not have AC at present is this the case?

    A small dehu in the basement will make a difference. I used to circulate basement air in my old home in Canada through out the house during the summer. I ran a Kenmore 40 pint dehumidifier down there, it kept the humidity under 60%. Keeping the windows closed and the drapes drawn during the day kept the heat out, so it was bearable without central AC
    Actually, I do have AC a 3-1/2 ton for 2600 sq. ft. but it only lowers humidity when OD is in 90's. Most time around here is 75* to 85* and humid. I push thermostat to try to remove humidity and end up with indoor temp in 60's.

    The unit may be over-sized, but when in the 90's everything seems better. Last year I had two estimates and both say 4 ton two stage recommended.

    For now I'm thinking Ultra-Aire dehu till the wife can be convinced, then I'll call someone else.
    Thanks.
    .

  10. #10
    Join Date
    Apr 2002
    Posts
    11,808
    do you run your fan all the time to try and even out air temperatures, or to filter the air frequently?

    If so try setting the fan back to the Auto mode

  11. #11
    Join Date
    Jun 2007
    Location
    Bucks Co PA
    Posts
    364
    Quote Originally Posted by Carnak View Post
    do you run your fan all the time to try and even out air temperatures, or to filter the air frequently?

    If so try setting the fan back to the Auto mode
    Thanks, yes probably the first piece of info I learned on here was to put fan on "auto". That did help a little.
    .

  12. #12
    Join Date
    Apr 2002
    Posts
    11,808
    Quote Originally Posted by Jack2007 View Post
    Thanks, yes probably the first piece of info I learned on here was to put fan on "auto". That did help a little.
    .
    Since you are eager to learn, perhaps consider having a tech come and drop your blower speed down a notch or two before you spend 4 figures on a dehumidifier

    If Auto fan and a reduced blower speed do not work, then odds are your home leaks like swiss cheese, you have some sort of steady exhaust fan running like a humidex or an attic ventilator, you have some leaking ducts in unconditioned space etc and unles you can adress these issues, your only bandaid fix is a dehumidifier

  13. #13
    Join Date
    Mar 2008
    Location
    Baltimore MD and Ridgebury PA
    Posts
    542
    Quote Originally Posted by Jack2007 View Post
    Actually, I do have AC a 3-1/2 ton for 2600 sq. ft. but it only lowers humidity when OD is in 90's. Most time around here is 75* to 85* and humid. I push thermostat to try to remove humidity and end up with indoor temp in 60's.

    The unit may be over-sized, but when in the 90's everything seems better. Last year I had two estimates and both say 4 ton two stage recommended.

    For now I'm thinking Ultra-Aire dehu till the wife can be convinced, then I'll call someone else.
    Thanks.
    .
    Yup, the unit is over-sized... hence it works better when temp is in the 90s and the unit is running more... as it stands now it brings the temp down quickly then shuts off (short cycles) and therefore little humidity is removed.

    As for the estimates with 2-stage 4 ton units... this is probably because 2-stage units are generally (always?) only available in full-ton models... so if the load calc calls for a 3.5 ton then you have to use a 4 ton... well that or a 3 ton but probably not a good idea. In any case, make sure a load calc is properly performed since you have low air infiltration and very good insulation. The advantage of the 2-stage 4 ton is that in the 1st stage it will run at roughly half its rated capacity (meaning 2 tons) which is good because it will run longer and therefore actually perform dehumidification. Then, when it gets hotter out the 2nd stage will kick in for that extra-needed capacity.


    For comparison, I live in Baltimore and my house was originally built in 1920. I gutted the house several years ago and installed foam insulation which seals against air infiltration and provides excellent insulation. My exterior walls however are only about R-13 because of the depth of the wall cavity that I had to work with compared to your R-20 wall insulation. My house is 1700 sq ft. I only have a 2.5 ton (single-stage) heat pump although I do have an oil furnace for my backup heat. As of late, my heatpump runs less than 50&#37; of the time... when it was hot out 2 weeks ago it ran maybe 75% of the time. My humidity is 55% right now. It is entirely possible that 3.5 tons is simply too large for your home except when the temperature is over 100 degrees or whatever. Do yourself a favor and do your own Manual J calculation... I'd recommend HVAC-Calc.
    Last edited by platchford; 06-22-2008 at 03:00 AM.

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