We have a non-standard house with a humidity and air quality problem and don't want to continue to throw good money after bad.
Summary
* Humidity in low to mid 60% in summer even in dry mode on mini splits
* ~3000sqft loft style, fully open main and upper floors, lower level with 2 bedrooms & baths
* Mitsubishi / Trane mini split, 5 indoor, 2 outdoor units (installed in 2020)
* Crawlspace fully encapsulated + Aprilaire E100, humidity good at 40%
* Radon mitigation in crawlspace
* Can run ductwork for main floor and lower levels
* Air circulator system with inlet in cathedral ceiling, and 3 supplies to main open living area
* Baseboard heat, gas
* Temps are great throughout the house using the mini splits and baseboard heat depending on the season
The approx 3000sqft house (in climate region 5) first and second floors are entirely open in a loft style with 2 bedroom sized "rooms" upstairs and an open catwalk connecting both. The lower level is kind of an "extension" downstairs and has 2 smaller bedrooms and bathrooms. Every part of the house is above an accessible crawlspace. When we purchased a few years ago, there was no AC in the house and the crawlspace vapor barrier was a mess and bare earth was visible everywhere. In the summertime, the lower level living space humidity can get up to 80%. Gas boiler for baseboard heat throughout the house.
There is a large grilled inlet and ductwork in the cathedral ceiling which draws in air from the main loft area ceiling and via a fan, circulates it through duct work that runs through the crawlspace then empties it into the main living area. It is just a fan, no conditioning.
We knew of the humidity problem and lack of AC before moving in because of mold in a lower level bedroom and contacted 2 well-known HVAC installers in the area. Both recommended mini splits throughout the house. 2 outdoor units, and 5 indoor heads and both companies were almost identical in sizing the units. This solved the cooling problem, but the humidity is still an issue. 60-65% in the summer even in "dry" mode and high 60%s in the lower level. If left in dry mode it just gets cold, the humidity drops about 5% then goes back up again. Newly installed engineered wood floors buckle in places. We have climate sensors throughout the house monitoring continuously, and the crawlspace humidity was over 80% at times.
It was then recommended by another HVAC company (3rd one now) to fix the crawlspace problem before anything else. So a crawlspace encapsulation company encapsulated everything and installed an Aprilaire E100 dehumidifier and took care of the humidity in the crawlspace. We have it set at around 40% (monitored with 3 sensors in the crawlspace in various locations), but it did nothing for the humidity in the rest of the house.
The 3rd HVAC company mentioned that the first two should have recommended central air where it is possible to run ductwork (lower level only), and then mini splits in the upper loft areas where it is not possible. The 3rd company actually took quite a bit of time trying to solve this, and here is where we're at:
* Lennox CBA25UH-0181 air handler in crawlspace just as a blower
* Install 3 supplies in lower level, install replacement ducts (original damaged) that were used by the air circulator mentioned above)
* Remove air circulator fan and replace that accessible ductwork with duct board.
* Use existing ductwork in cathedral ceiling for inlet
* Aprilaire basement kit 5442 with dampers to switch the existing E100 dehumidifier between crawlspace and main living space.
* Aprilaire 8100 ERV (air quality is also a concern)
All of what is proposed makes sense to me, but I would appreciate any guidance. I'm looking at this a lot more closely than we did with the mini split work and because of the results there, want to fully understand why each component is chosen and if it is the right option. The question I have here is there not a cheaper ducted blower or air handler that is designed to just circulate air instead of one also capable of AC? Other than that, all the other pieces make sense but would appreciate any help.
Thanks
Summary
* Humidity in low to mid 60% in summer even in dry mode on mini splits
* ~3000sqft loft style, fully open main and upper floors, lower level with 2 bedrooms & baths
* Mitsubishi / Trane mini split, 5 indoor, 2 outdoor units (installed in 2020)
* Crawlspace fully encapsulated + Aprilaire E100, humidity good at 40%
* Radon mitigation in crawlspace
* Can run ductwork for main floor and lower levels
* Air circulator system with inlet in cathedral ceiling, and 3 supplies to main open living area
* Baseboard heat, gas
* Temps are great throughout the house using the mini splits and baseboard heat depending on the season
The approx 3000sqft house (in climate region 5) first and second floors are entirely open in a loft style with 2 bedroom sized "rooms" upstairs and an open catwalk connecting both. The lower level is kind of an "extension" downstairs and has 2 smaller bedrooms and bathrooms. Every part of the house is above an accessible crawlspace. When we purchased a few years ago, there was no AC in the house and the crawlspace vapor barrier was a mess and bare earth was visible everywhere. In the summertime, the lower level living space humidity can get up to 80%. Gas boiler for baseboard heat throughout the house.
There is a large grilled inlet and ductwork in the cathedral ceiling which draws in air from the main loft area ceiling and via a fan, circulates it through duct work that runs through the crawlspace then empties it into the main living area. It is just a fan, no conditioning.
We knew of the humidity problem and lack of AC before moving in because of mold in a lower level bedroom and contacted 2 well-known HVAC installers in the area. Both recommended mini splits throughout the house. 2 outdoor units, and 5 indoor heads and both companies were almost identical in sizing the units. This solved the cooling problem, but the humidity is still an issue. 60-65% in the summer even in "dry" mode and high 60%s in the lower level. If left in dry mode it just gets cold, the humidity drops about 5% then goes back up again. Newly installed engineered wood floors buckle in places. We have climate sensors throughout the house monitoring continuously, and the crawlspace humidity was over 80% at times.
It was then recommended by another HVAC company (3rd one now) to fix the crawlspace problem before anything else. So a crawlspace encapsulation company encapsulated everything and installed an Aprilaire E100 dehumidifier and took care of the humidity in the crawlspace. We have it set at around 40% (monitored with 3 sensors in the crawlspace in various locations), but it did nothing for the humidity in the rest of the house.
The 3rd HVAC company mentioned that the first two should have recommended central air where it is possible to run ductwork (lower level only), and then mini splits in the upper loft areas where it is not possible. The 3rd company actually took quite a bit of time trying to solve this, and here is where we're at:
* Lennox CBA25UH-0181 air handler in crawlspace just as a blower
* Install 3 supplies in lower level, install replacement ducts (original damaged) that were used by the air circulator mentioned above)
* Remove air circulator fan and replace that accessible ductwork with duct board.
* Use existing ductwork in cathedral ceiling for inlet
* Aprilaire basement kit 5442 with dampers to switch the existing E100 dehumidifier between crawlspace and main living space.
* Aprilaire 8100 ERV (air quality is also a concern)
All of what is proposed makes sense to me, but I would appreciate any guidance. I'm looking at this a lot more closely than we did with the mini split work and because of the results there, want to fully understand why each component is chosen and if it is the right option. The question I have here is there not a cheaper ducted blower or air handler that is designed to just circulate air instead of one also capable of AC? Other than that, all the other pieces make sense but would appreciate any help.
Thanks
source https://hvac-talk.com/vbb/threads/2236357-Humidity-problem-even-after-mini-splits?goto=newpost
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