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Consider the whole issue about indoor air quality. Mechanical fresh air of an air change in 4-5 hours assure purging of all chemicals and the renewal of oxygen. Even if chemicals are not present,...

My guess is that you get plenty of fresh air change during cold weather and a little wind. Mainly the stack effect makes the house fresh air infiltration increase. Calm wind and mild temperatures...

Most deep basements in green grass climates need a good dehumidifier more than an a/c.
What is your climate. Basements are a little on the cool side unless you have high activity.
I would duct in...

How about using the old return space near the floor with the duct going to the dehumidifier. The dehu supply goes to the a/c supply duct down stream of the a/c cooling coil. Fresh air goes to the...

You may have a damp spot in the drain pan under the a/c coil. Recheck the draining of the pan, level without a wet corner.
Now that you have reduced the fresh air passing through your home by...

Best to have an independent return from the open part of the home to the dehumidifier. This assures good mixing of the dry air throughout the home via the a/c supply/dehu supply.
Most new a/c...

Sofit vents are intakes also and therefore a fresh air intake can be in the open sofit. Bathfans, kitchen hood and clothes drier need to be +3 ft. from the fresh air intakes. Also avoid car parking...

Any surface temperature below the dew point of the surrounding air will have condensation. Your insulation has a poor or no vapor barrier on the warm side of the insulation. 0^C duct surface with...

Crack a window any time the condo is occupied during calm winds to get fresh air change.
The effect on the inside moisture level depends on the outdoor dew point.
An example is 40^F, 100%RH a...

Or crack a window!
Regards Teddy Bear

The %RH inside your space is dependent on the amount of moisture in the outside infiltrating fresh air plus the moisture the occupants add minus the moisture removed by your a/c.

Outdoor air in...

Nat gas is cheapest heat source if available. Single speed a/c or heat pump combined with the dehumidifier/fresh air will keep the home dry enough to avoid mold/dusts and be very comfortable.
Keep...

Climate of the home is the location.
If a basement or crawlspace is kept dry and free of polluted materials, the air can be mixed. In fact, when the wind blows and the air handling equipment mix all...

A good air filter should have no effect on the ducts size. The ULtra-Aire 98H connected to the a/c supply could increase the air passing through the supply ducts to the home. The ideal UA install...

Cool mist humidifiers require a good air filter down stream to remove the solids left in the air after evaporation of liquid water. We are talking high merv filters +11. Steam humidifiers leave the...

Fix the motor and operate with merv 7 filter. Measure the results. End the discussion.
ECM motors are easier to adjust the air flow???

Good tech will get to the bottom of this!
Keep us posted....

My mistake on missing "not", knowing the actual temp/%RH in and out of the a/c would tell us is the air is high or low.
Many comments are intended to sell filters.
Find a knowledgeable tech get...

OK?
Keep in mind, more restriction, less air is moved. Remove all restriction and most blowers will overload while moving a lot of air.
How come you did give us some measurements (temp/%RH)...

I also agree that restricting air flow decreases the load on a squirrel cage blower. Also the first move should be to lower the air flow by using taps provided for adjusting the blower speed.
Keep...

Is there any moisture on the windows after a cold evening? IN cold green grass climates, the limitation is excess moisture on the windows. I suspect your %RH meter in not calibrated properly. Buy a...

I like simple, you need fresh air on/off when occupied and %RH for the dehumidifier. If the home is occupied most of the time, leaving the fresh air on is OK. If you have a routine occupancy, a...

Depending on the size of the crawlspace. If less than 1500 sq.ft., a supply from the main whole house may handle the space. A separate dehumidifier makes it simpler. Where are a/c air handlers...

My experience is the that the stuffy air and high %RH is a 3 mild seasons of the problem. With cold outside air and winter wind, most home get enough fresh air. If anything they have so much dry...

Slowing the fan speed slow cooling rate improves moisture removal. Setup which includes fan speed adjustment to get ideal moisture removal is basic.
Some installers do not have a clue.
In the end...

At the end of the cooling cycle, the cooling coil is loaded with moisture. If heat is called for within 1 hour, expect any moisture left on the cooling coil to rapidly to evaporate and pass on the...

Just to make sure that you understand a bubble plastic pool insulation that will float on top of the water in the crawlspace will contain the moisture under the plastic that will grow mold and will...

Good question.
Each lb. of moisture removed is 1,050 btus of condensing energy. Plust the electricity converted to heat, 580 watts X 3.4 btus = 5,129 btus per hour, +-.
Close enough?
Keep in mind...

Yes, the heat from the moisture removal process is added to the home. First off, a well setup a/c should be able to maintain <50%RH during peak cooling loads. If not, the a/c air flow can be adjusted...

A crawlspace that floods is the toughest problem. I suggest a bubble pack plastic like on a pool. The plastic would float on top of the water. Fasten the plastic to the wall with a strip of plastic....

[QUOTE=PBJ918;25806392]I am located in Tulsa, OK. I have an 1100 sqft 1920 craftsman house that I totally gutted in 2012 and made into a very tight, efficient house. All exterior walls, roof deck and...

There is a lot of "Just live with it going on".
Fresh air is most benefical during the three mild seasons of the year. No wind or stack effect to make fresh air pass through the home removing...

Which house first?
Is the larger new home spray foam also?
Most experts suggest a filtered fresh air change in 3-5 hours when the home is occupied. Homes have exhaust devices like a clothes...

No need for UV unless your fresh air has a pollutant that needs to be controlled by UV.
With adequate fresh air change to purge indoor pollutants and renew oxygen, filtering spores/pollen/dust is...

Top indoor air quality in a home starts with a fresh air change in 4-5 hours to purge indoor pollutants and renew oxygen at a minimum when occupied. When the outdoor dew point is 50-55^F and the...

Typically a 6" fresh air duct is routed from outside to the inlet of the dehumidifier and joined with a return duct from the open part of the home. A 2,500 sq.ft. home needs about 80-100 cfm of...

Good question. Maybe the difference in running hours and dehu coils may be colder. A/cs have plenty of failures also.
We will keep on trying to improve.
Large coils have thicker copper tubing?...

Sorry about missing your original post.
Keep us posted on any additional question and how the solution works out.
Regards Teddy Bear

20 years ago we had <2% failure rate without any special treating or coatings.
We are currently struggling to get that low with the best of coatings and details. The failure rate has declined...

Fresh air should not be limited to equipment operation. Fresh air is needed when the home is occupied to purge indoor pollutants and renew oxygen. Needed for the health of the occupants!

An air...

Monster hoods are 650 cfm when measured. Regular hood more like 100 cfm on high. Ratings are higher but seldom deliver more than 50%.
Seldom do homes need more than 200 cfm of exhaust. There are...

Lets get back to the problem. Mold inside the ducts or on the outside? My concern is that you do get mold in the new ducts like the old ones. What climate is this home located in? Cold climate...

Probably a freeze-up of coil as the unit died. Or could have been an strong dip in outdoor dew point?
Regards Teddy Bear

Looken good!
Keep us posted.
Regards Teddy Bear

All have had fun with cooling coil refrigerant leaks. All Therma-Stor coils are epoxy coated and baked. This has dramatically reduced the leaks, but still have occasional leak. Probably chemicals...

Sorry, I missed that. Dew point is different than temp/%RH. What is the temp/%RH on a/c supply? I will figure the dew point.
Another point, Fan mode should be "auto" mode. No fan during off...

The Quest dehumidifiers are high efficiency dehumidifier made in the USA. They remove 6-9 lbs. per KWH plus provide significant free reheat like 12,000 buts per KWH while removing the moisture. ...

Musst be a winter climate?
Fresh air change is a must, a fresh air change in 4-5 hours minimal when occupied to purge indoor pollutants and renew oxygen. A valid point on using mechanical fresh air...

Are you saying that because your home is cold, it is over-ventilated? The ideal fresh air change rate when a home is occupied is ranges from a fresh air change is 3-5 hours to purge indoor...

Any organized fresh air ventilation? Most suggest a fresh air change in 4-5 hours when the home is occupied with normal materials in the home. Without fresh air change, the home will vary with VOC...

Most home have excess summer moisture retained in their homes. Start by operating an exhaust fan when the moisture shows on the cold glass. It takes a couple weeks of 24/7 exhaust ventilation to...