Hi everyone,
I’m working on ideas for moving some of the warm air created in my 1970s-era attached sunroom/sunspace I recently renovated into my home, and I’d appreciate some feedback. I’ve attached a picture of the sunroom. The dimensions are approximately 18’ x 16’ with the south, west and north sides being all 76 x 34 clear tempered insulated glass units with ½” air space in between. The total air volume within the space is approximately 5000 cu ft and I’ve sealed it to be reasonably airtight (although there are 4 sets of patio doors, 2 up, 2 down, that certainly leak some air). The floor is poured concrete approximately 5” thick; I plan on adding a little more thermal mass with a “flooring” layer of 2.5” pavers later this Fall. There is no other thermal mass other than the shared wall with the house which is stick construction/thin layer of stucco.
The sunroom spans two stories of the home: the basement level of the home is the floor level of the sunroom and there is a standard size door between the two. And there is a balcony/walkway at the level of the main floor of the home. There are two sets of sliding glass patio doors between the main level of the house and the sunroom walkway. When we’re home, it’s easy enough to slide those patio doors open and get some heat moving into the house that way (and even get some circulation by cracking open the door between the basement level of the home and the sunroom). But obviously this arrangement only works when there is active heating and when someone is there to close things up when that heating stops. I’m wanting to install some kind of fan-driven system that would automatically move air from the sunroom into the house when the sunroom temp rose above a certain level, then shut off that air movement when the temp fell below.
The basic design I’m playing around with is running a 6” or 8” standard wall/vent pipe vertically along the wall shared by the sunroom and the home (on the sunroom side). Since the roof/ceiling of the sunroom is a simple sloped/shed design, the “intake” end of the pipe would run vertically to about 6” or so of the ceiling to capture the warmest air pooling there. The pipe would extend straight down vertically and then penetrate through the wall and into the house with a “T” or elbow. I’d install a thermostat-controlled inline fan that would blow heated sunroom air into the house above a set temp, but turn off below that temp. I would install some kind of gravity or spring-controlled damper to close the pipe when the fan was not blowing, hopefully preventing (most) air movement in or out.
Finally, I was considering the need for some kind of “return air” capability, otherwise it would seem I’d just be pulling much colder outside air into the sunroom fairly quickly once the warm air had been pulled into the house. So I was thinking of installing a short section of 6” or 8” pipe (or some kind of vent) through the wall at the basement floor level, again with a gravity or spring damper. The idea would be that when the inline fan was blowing, that would create sufficient pressure (?!) to pull that basement-level damper “open”, pulling cooler basement into the sunroom and creating a continuous “heating loop” from basement to main level.
So that’s the outline of a basic plan, but I have more than a few questions:
1. Is the overall design good, or is there another approach to consider that would accomplish the goal?
2. 6” versus 8” pipe? The 8” pipe elbow/”T” is pretty darn big and unsightly, and may be more than I need to move the air for this particular sunroom. 6” inline fans, however, seem to be limited to around 250CFM which may not be sufficient to create the pressure to open the basement-level damper/pipe.
3. Would it be better to penetrate the wall near the ceiling level of the main floor of the home, or near the floor level? I suspect the floor level might be better for air movement, but ceiling level would interfere less with furniture placement.
4. I’m not sure of the best place in the pipe to mount the fan and the damper…I was thinking the damper right near the “end” of the pipe penetrating into the main floor of the house, with the fan mounted just behind it (although people seem to have more luck with gravity-powered vertically-mounted dampers than spring-powered horizontally-mounted ones)
‘Any advice/feedback greatly appreciated!
