new construction IAQ
In the process of building. I have another post about what to do with new construction, but here is a question about dehumidification and fresh air intake.
House is two story 3400 sq ft with two story great room and foyer in central Georgia. Two heap pump systems (trane)I want to introduce fresh air into the home. Hvac installers suggested a fresh air kit from honeywell. Says it works well and does not cost very much. I asked about dehumidification as well and they suggested the honeywell 65 pint but said that could be added later once I live in the house and decide if it is needed. I also want to pull fresh air in when bath and stove fans come on.
What are the thoughts on this?
One of the things that was said to me was that when I run the AC, it will pull the humidity out; however, I tend to not want to run the AC when we are at work and also dont want to run it during shoulder seasons which can be much during sept to may. Is this proper or am I setting up for failure? As a side note, I do this with my current 1400 sq ft home and end up turning the AC on to get humidity down even though the indoor temp is ok since there are no IAQ devices on this one.
Im looking for the best bang for the buck since the budget for the new house is pretty much tapped.
How tight is the building construction. How many tons of a/c are the two systems.If you are planning to induce fresh air into the home then a good approach would be installing a ERV. A seperate dehumidifier would also be beneficial since you are not wanting to run a/c units. In a high humidity climate zone, in order to maintain comfort levels inside your home the a/c or dehumidifier is going to need to be automated. Being at work has no bearing on your homes comfort level. The equipment must be able to run regardless whether you are at home or not. If you are trying to save on operating cost, careful considerations must be addressed. Consulting with a mechanical engineer, energy analyst may be in your best interests.
I will have two trane units. one 2.5 ton the other 3.5 ton. Im assuming better than avg or avg for todays construction in the southeast. Good quality Vinyl windows, batt and blown in insulation r15 in walls, r38 attic, house wrap. I spoke about the ERV but that was stated as not the best bang for the buck compaired to the fresh air .
Not wanting to run the hvac when not at home and other times would be mostly to help offset utility costs. the shoulder season though tends to be comfort induced as well since sometimes its proper temp in the house but too humid.
You have the right ideas. You know you'll want the dehu, and you stand to gain nothing except headaches by getting it installed later. So why wait? Get it installed now. For the first year, I suggest overventilating to get rid of the VOCs from the outgasing of building materials.
-If you won't turn it on then nothing else matters.
look at a venmar we have done them on some n.c homes here in az
Thermastor provides three sizes of dehumidifiers to Honeywell. The larger the more efficient they are removing lbs of H2O per kWh. What is not being said is if you use a set back thermostst during the day the A/C units can recover the temperature in short order upon your return, but they do not have to run long enough to reduce the humidity that is common in your part of the world. If the dehumidifier has done it's job that won't be a problem. What you should also consider is bringing in fresh air only during the time you are home. The common controls are not set up for that right now, but the new Prestige IAQ stat can be upgraded as new features become available. Go for it! Dehumidify and install a motorized outdoor air in take damper and the Prestige IAQ with outdoor sensor. You need to dehumidify the air twice as many hours per year than you need to cool it to be comfortable.
Does this home have a basement or crawlspace, finished or sealed? Where are air handlers located? If basement/crawlspace with an air handler, I suggest a minimum of a 90 pint per day whole ventilating dehumidifier located on the lower a/c with fresh air ventilation. This can be connected to the air handler and provide a small amount of dry air to the basement. Fresh air ventilation should be controlled by a occupancy timer. To optimize the indoor air quality, ventilated when the home is occupied and maintain <50%RH throughout.
Originally Posted by williemon
The dehu will maintain <50%RH with a/c off or on which minimizes the utility cost.
I work for Ultra-Aire which is the brand I prefer of course. The DEH3000 control provides an occupancy timer for fresh air ventilation on a schedule.
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"