House Dehu- Fresh Air- Heat Recovery?

[Jack2007]

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 ?
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[teddy bear]

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

[teddy bear]

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

[Jack2007]

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 ?
.

[teddy bear]

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

[pstu]

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

[dash]

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.

[pstu]

What Dash said, first of all. It would be a shame to get a dehu as a fix, and leave another gross problem unsolved. My S.Texas house without any kind of separate dehumidification would be able to get approximately 55&#37; RH at 78 degrees, with outdoor air around 95F and 72 dewpoint. Wherever you are in PA, the climate is likely not as adverse.

[dash]

Still rainey and washer and dryer running for hours ,now 50% and 47%.

[Carnak]

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

[Shophound]

Still rainey and washer and dryer running for hours ,now 50% and 47%.

The other morning I had 73 degrees outdoors, with 79% relative humidity. Indoor was 74/48%, and that after a morning shower. Cool, wet weather, for as short as it lasted (hit low nineties later in the day), and single stage central a/c kept humidity below 50%.

[beenthere]

Came home from a birthday party for a nephew. Stat set to 74, it was at 54%RH, started dishwasher when we left, dang, just didn't feel good. Set stat to 72, its now 73, and the RH is down to 50%, starting to feel much better inside now.

[teddy bear]

The other morning I had 73 degrees outdoors, with 79% relative humidity. Indoor was 74/48%, and that after a morning shower. Cool, wet weather, for as short as it lasted (hit low nineties later in the day), and single stage central a/c kept humidity below 50%.

No cooling load and humidity stays low while high outdoors humidity is high, is a sign of little or no infiltration. If you were getting a air change every four hours, what the indoor %RH be? I think it is a great starting point. Do make-up air ventilation when the home is occupied. During hot weather your a/c will handle it. If there is no way that you can handle a dehu, just don't ventilate during wet cool weather. Regards TB

[Jack2007]

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.
.

[Carnak]

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

[Jack2007]

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.
.

[platchford]

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.

[teddy bear]

The beauty of the dehumidfier is that adding a dehu to any sized system provides <50%RH. A one ton a/c is unable to provide <50%RH when the outdoor temps are <75^F. I have not run may a/c to date. MY basement is 68^F,<50%RH. Cracked window and 90 pint dehu operating. $15/mo. electrical. Regards TB

[Carnak]

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

[Jack2007]

This is an uninformed question, but, since a dehu is used to bypass the AC unit (intake from return - dehu output to supply), could a "one" ton complete AC unit be used as a bypass of the bigger unit ??

Why ? Well, if a one ton could provide the kind of dehumidification that a regular whole house dehu can perform it may help keep electric costs down. Would this not also be a desirable auxiliary AC unit to be used when temps are not great enough to run bigger unit ??

Guess I'm feeling frustrated at the moment. My AC is down right now the condenser fan is not running. Called the service company who sent a guy out and replaced a capacitor. Unit ran for 1 1/2 hours then fan quit again. Called back they told me thursday is earliest they can come back.

Thought maybe a one ton unit (used in a bypass) could be an emergency AC for minimum comfort as well as a dehu.
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