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AC duct placement in hydronically heated home

Posted by OntarioMom (My Page) on
Sat, Aug 4, 12 at 10:55

Hi GW,

For those of you who have hydronically heated homes, where did you place your AC duct work? We have been back and forth many times with our HVAC contractor trying to find both an efficient and asthetically pleasing duct placement. I feel very frustrated with the process.

Here are the details on our home:

- Original home was a raised ranch
- 2 story addition was placed on the back half of home (part that looked like a standard bungalow before due to grade)
- All of our ceilings including basement, main floor and upper floor are 8 feet high
- All heat will be supplied by underfloor hydronic heat

We have discussed using either one large air handler or two smaller ones. My priority is to avoid drop down boxes in the main living area (basement would be okay) as our ceilings are only 8 feet. We are likely going to have one air handler in the new attic over the new second floor and frame that area and drywall in a section so it is conditioned space. We are not sure where to place a possible second air handler, although theoretically we could also do another conditioned attic space in the old attic (the original attic that did not have an addition built over it).

Please tell me what you worked out, and where you had to give up ceiling height for drop down boxing, or closet and/or wall space for duct runs.

I look forward to hearing how others have solved this problem. TIA!!


Follow-Up Postings:

RE: AC duct placement in hydronically heated home

Try high pressure systems like Unico with main trunk in the attic using duct-board.

Unico even has small caps to use to close off the outlets during heating season.

RE: AC duct placement in hydronically heated home

Hi Brickeyee and thanks for your reply!

I do hope we can put the main trunk in the attic. It think those duct-boards (saw some by Certainteed) look great! As per the high pressure system, are you referring to an air handler or the boiler? If by chance you are referring to the boiler, we have already had a unit purchased some time ago that was a low pressured unit (Elite 220). Please clarify.

Later, I will post a floor plan of our home, for any other suggestions.


RE: AC duct placement in hydronically heated home

Hi again,

I decided to also post my question on the heating and cooling forum, so please accept my apologies for cross posting.

Here are some floor plans of our home which has almost finished the framing stage. We have made some changes to the plan (i.e. kitchen changes, laudry, moving fireplace to corner, etc) but they are the only reasonable sized plans I can post. The basic square footage and location of walls and closets is quite accuate).

Here is the main level. The shading represents the HVAC guy's first plan for drop down boxing on main level, which we will not be doing (our ceilings are only 8 feet so drop downs would really be a drag).


Here is the bedroom level. This upper level is over the following rooms on the main level: great room, dining room, main floor baths, laundry and kitchen (i.e. upper level is less square footage than main level).


Basement level (full 8 foot basement). This plan cuts of an 10 foot by 13 foot office at top of screen and part of the tandem garage. The study is on one side of the staircases and the garage on the opposite.


Thanks for any input on what would work in our floor space to avoid drop downs (or greatly reduce drop downs) in our main and bedroom levels.

Also, I would love to hear where others have hidden their vents.



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