Replies

1. 
   wjrobinson | May 10, 2012 04:45pm | #1

   Have you thought of contacting an architect with green building experience? In my area we have at least one. The reason I suggest this is if you learn here a little, you still need installation experience along with all the other phases of construction needing coordination and experience and successful past outcomes.

   Who are you buying from? Who is installing? Who is maintaining? If you know these answers then you should be able to answer your posted question.

2. 
   Lizzieplants | May 10, 2012 05:09pm | #2

   I am working with a builder that has green building experience and who is recommending a mini-split system as one option because it provides both heating and cooling in one system. The noise issue is unique since noise control is not usually an issue in a residence.

   I want to see if anyone at GBA had dealt with noise control in designing the HVAC system in a tight home.

3. 
   user-1012653 | May 10, 2012 10:33pm | #3

   it is my understanding jumper ducts (through the ceiling, not through the wall) greatly reduce sound travel. We use this design often on schools (from classrooms to halls for example) without issue or noise complaints. With your plan, I would guess you could have a jumper duct from one office into the hall. Air circulation can be aided with the HRV and ceiling fans.

4. 
   claumergiddens | May 11, 2012 02:47pm | #4

   Elizabeth:

   Here are a couple of options that I have specified for past for clients with a similar set up to yours.

   1. DUCTED OPTION: Assuming you have an encapsulated attic, you could use another ducted unit serve the second floor, install the Tamrack Return Air Pathways (RAP), instead of jumper ducts, to get return from each room to a central return grill in the central hall ceiling. In a tight, well-insulated home, 800 s.f. will likely have a max load around 6-7,500 btu/h. The smallest ducted fan coil is 9,000 btu/h and would serve this area well (it's OK to be oversized with mini-splits).

   2. DUCTLESS OPTION: Install ductless unit (wall-mounted, floor mounted, ceiling cassette) in one room and use an Air Share Fan (http://www.tjernlund.com/airshare_ventilation.htm) to push air in to the adjacent rooms. I would recommend the RAP, again, as it has very good sound and light control, with less material. Building America did a study on their effectiveness, and showed some pretty good results. http://www.ba-pirc.org/casestud/return_air/index.htm

   p.s. the floor mounted unit is probably the only ductless unit that can be recessed in to a wall cavity and "hidden" with a decorative grille with enough free air flow.

5. 
   user-1012653 | May 11, 2012 03:05pm | #5

   great info Chris. About how much do one of those transfer fans run do you know?

6. 
   Lizzieplants | May 11, 2012 03:08pm | #6

   Thanks Chris,

   Sounds like some good solutions. I am thinking we could also use the Air Share fan to get the warm air from the wood stove around when we are using the stove. Does the air share use much energy?

7. 
   claumergiddens | May 11, 2012 05:24pm | #7

   Jesse: I've seen them run anywhere from $100 - $200. Amazon sells them for about $130
   http://www.amazon.com/Tjernlund-AireShare-Room-To-Room-Ventilator-Hardwired/dp/B000UC7ACE

   Elizabeth: The fans are rated at about 25 watts, or .5 Amps. That's about the same or less as the fan in the indoor units of the mini split systems.
   Here is their spec sheet: http://www.tjernlund.com/Tjernlund%20_AS1_AS1P_AireShare_Spec_Sheet_8513030.pdf

8. 
   wjrobinson | May 11, 2012 05:50pm | #8

   Chris, love your post. Any of us that have not used a mini split need to know how to and how not to, set them up.