Electric Radiant install -basement floor
Heat our entire house w/ a woodstove on main floor (having super-insulated this old house w/ sprayed-in foam -GREAT!). Means that it’s a bit chilly in basement now, w/ furnace never running. -Northern Alberta, 4-5 months down to -30, sometimes -40!
Basement is all utility, no need for supplemental heat, except my 12X20 home workshop. Would like it a bit more comfy down there -when I’ve the odd time to work down there. Seems electric radiant is the most cost- & energy-effective for such small area. -Will eventually be run solar-ly. Now, I’m a carpenter, lotsa cement-work experience. The 4″ cement slab was not insulated below it, but after lotsa research & checking w/ co-workers (HVAC sub-trades) I’m going to install the wiring right on existing slab so that it will act as a huge heat-sink for basement (rather than insulate against the heat going down). Then will pour a few inches of cement over top.
Over worktable-traffic’ed area (where I may pull out saw-tables etc,. concentrating the weight over the wired-area with the tables casters) I am going to SET INDUSTRIAL CERAMIC-TILE DIRECTLY INTO THE CEMENT. -Apparently common practice in South Africa.
Anybody have any experience in that practise?
Thanks, Barb
Replies
Just an idea: The existing slab may be an awfully big heat sink--what about a vapor barrier, then 2" of Stryrofoam, then the heat wire, then new concrete? I was just thinking that you may end up pouring a lot of heat into the slab and the soil under it before you get heat that will begin to warm you. The up side is that once you heat the old slab and so on, it will take a long time to cool down again.
Thanks for your thoughts, Danno. I'm still considering...
Here's the latest, from the northern Alberta WarmWire distributor:
1) Use a porcelain tile to cover your entire floor area. It is most durable, holds the heat nicely and can handle just about any castor or point load. However, you need the self-levelling material over the wire, let that dry and then set your tile into ceramic tile thin-set cement. Not directly into the self-level.
2) Lay the wire directly onto your slab. You can bond the WarmWire strapping to the slab using a PL400 adhesive.
3) floor space draw to be 10.0 amps, on 15 watts per square foot
So, I'm giving it more thought based on his operating costs, 15w/sq.ft, when our power's at $0.23/KwH...
In no big rush, so I'll gather more ideas...
You may want to look on the Breaktime forum because there is a discussion there from a guy who wondered whether he should bust out his old slab in his garage in order to do a radiant heat floor, or whether he should top it with new concrete and whether he should insulate before doing it. I think the consensus was to insulate over the existing slab, then put down the wire (or water tubes) and then pour the topping. Someone wrote about the tremendous heat sink that the old, uninsulated slab and the earth under it would be and how expensive it would be to bring the temp up to a point where the heat would do any good in the space.