Do zones really work in a slab system? - GreenBuildingTalk - GreenBuildingTalk - Green Building Forums on Insulating Concrete Forms (ICF), Structural Insulated Panels (SIP), Radiant Heating, Geothermal Heat Pumps, Solar Power, Green Construction Projects - Green Building Technologies

Unanswered Active Topics

Forums Search Members

Do zones really work in a slab system?

Last Post 27 Apr 2010 12:47 PM by Brock. 6 Replies.

Sort:

	Prev Next
You are not authorized to post a reply.

Author

Messages

kicker_92

New Member

Posts:65

21 Apr 2010 12:32 AM
So say you have a basement slab, and you descide to seperate the rooms into zones. With the concrete between the zones being a good thermal conductor, would the zones still work? It appears that concrete has a r-value of around 0.1/inch. Assuming Zone A is heating the slab to 80°F, and zone B is turned off, there will be a very gradual temperature gradiant between the zones. My question is: Aside from spaces that are seperated by great distances, is there any point in zoning a basement slab? (or do you need to put in a thermal break between zones?)

NRT.Rob

Veteran Member

Posts:1741

21 Apr 2010 08:32 AM
this is different based on heat load/room temp differential between the areas, and linear border footage between zones. If you had a wide differential and lots of border area, it might be a problem. Generally though it's not very common for heat bleed to maintain a regular room temperature. if you had a small storage area with room temperature space on a couple sides, it might not be able to stay as low as you want. but that's about it, really.

Rockport Mechanical<br>RockportMechanical.com

kicker_92

New Member

Posts:65

21 Apr 2010 11:54 AM
Thanks Rob, my situation is a 26ft long basement wall between living space and a unheated storage room. There is also a lot of rebar passing through this junction which will help conduct the heat. During the winter, I'd expect the storage room to be around 55°F, and the slab around 80°F. I will add a 2" strip of insulation to thermally seperate the slabs, but this got me thinking about other zones areas. We have the tubing layout setup to have the bathrooms on a seperate zone to keep them warmer, but with the amount of perimeter am concerned that they will be difficult to maintain a higher room temp. It woudl be much easier and cost effective to just run the tubing through the whole floor as one zone.

NRT.Rob

Veteran Member

Posts:1741

21 Apr 2010 12:18 PM
don't forget to insulate the partition walls if you want a room to be that much cooler. heck the room probably doesn't even need heat to stay that warm; don't insulate the partitions, and just let heat gain from adjacent spaces do its thing. maybe loop it for "future heat" if it got converted to living space or something, but don't connect it immediately. for normal differentials (5 to 10 degrees room temps max) this isn't generally much of an issue.

Rockport Mechanical<br>RockportMechanical.com

Brock

Advanced Member

Posts:599

22 Apr 2010 10:43 AM
We had a bedroom in our basement that was zoned separately in the slab, for the first year we just had sheet rock on the bedroom side to close off the space. About two months ago we sheet rocked and plastered the rest of the basement and for sound reasons we insulated the walls of the bedroom. I was really amazed how much warmer or cooler the bedroom is now and how much the room temp is based on the floor temp. It is also MUCH more quiet insulating the walls is cheap and easy and make a big difference, unless you want the heat to migrate.

Green Bay, WI. - 4 ton horizontal goethermal, 16k gallon indoor pool, 3kw solar PV setup, 2 ton air to air HP, 3400 sq ft

kicker_92

New Member

Posts:65

22 Apr 2010 11:29 AM
Do you noticed that the edges of the slab adjoining that space are noticibly cooler? I'm wondering if any extra row of tubing shoudl be added to make up for the heat loss.

Brock

Advanced Member

Posts:599

27 Apr 2010 12:47 PM
Not really. You can feel it in the floor if you slowly take steps towards the wall barefoot and it happens that the door is on a footing so you can feel that is the coldest part, but in the room on the adjoining walls I don't notice it at all. You rarely stand within a foot of a wall. The room itself is very even.

Green Bay, WI. - 4 ton horizontal goethermal, 16k gallon indoor pool, 3kw solar PV setup, 2 ton air to air HP, 3400 sq ft