Originally Posted by
somedude
Hi,
My house had been sprayfoamed last year, and the soffit vents have been sealed which made the home much tighter, and the amount of fresh air in the house has been reduced considerably, requiring mechanical ventilation.
I'm in south florida, so humidity is a major concern. My plan has been to install as follows:
Ultra-Aire XT150H with filter removed, input side connected to Lennox Pure-Air. Lennox Pure-Air with ducts connected to both inside return, as well as a fresh-air vent from outside connected to a Honeywell EARD6 damper. I was planning on putting MERV8 filters at both the input from outside air as well as the source return to catch the large particulate matter and spare the HEPA filter in the Pure-Air.
The output side of the Ultra-Aire XT150H will be connected to dedicated ductwork to all bedrooms, living room, family room, dining room (no kitchen, bathrooms -- don't want positive pressure in areas with potentially low air quality).
This plan seems to make a lot of sense to me as it will have positive pressure in all living spaces with HEPA filtered outside air.
The system will not be connected to the existing HVAC system at all, and will be ducted into both zones of the house. The two zones are the main living space (with 3 bedrooms), and the master bedroom as a separate zone. The house is all one level.
The two questions are:
1) Sanity check on this build, does it make sense?
2) I will have a VisionPro IAQ controlling the system, as well as the main living space zone. I'd like to wire it up to have the fan in the XT150H constantly running, and have the DHUM leads hooked up to turn the XT150H compressor on and off, and the VENT leads hooked up to open or close the EARD6 damper. The idea behind this is to always have air circulating around the house to minimize hotspots, always have filters running, and always maintain positive pressure in the bedrooms. My concern is that having the fan constantly running will cause signifigant amounts of condensation on the coils to re-humidify.
Thanks in advance!
It is important to have a minimum of a merv 11 air filter on the return to the dehumidifier. If all of the air flowing to the Ultra-Aire passes through the Pure Aire Merv 16 filter, ok. Operating the fan on the UA constant is ok but does a increase the re-evaporation rate. This may be unavoidable and is minimized by a wide band on the dehumidistat. Suggest 8%RH dead band. Remember during high cooling loads, the a/c should be able to maintain <50%RH even with fresh air and the occupants in the home. As the a/c cycle declines during low/no cooling loads, the UA will dehumidify as needed to maintain <50%RH. Thus the heat from the dehumidifier should not be noticeable when distributed throughout the home. I suggest best connect the fresh air to the dehumidifier as the many hours of fresh air ventilation and dehumidification are need throughout the year. Dehumidifying the fresh air as before it enters the home is a benefit. There are more hours of dehumidification than cooling in a foam insulated home in FL. There is a Merv 14 filter option available for the Ultra-Aire that filters fresh and house air before the mixed air enters the Ultra-Aire.
It is not clear how you are going to operate your air handler with the UA. If the home is not occupied 24/7, why ventilate 24/7? The UA DEH 3000 controller has an adjustable ventilation schedule and and an adjustable dead band dehumidistat.
Sorry about missing your post. Thank you for choosing the UA product. It is the best dehu.
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"