Solar gain on a radiant slab

Eddie Grierson

I need a little advice guys. I have a job I am bidding right now and I am trying to come up with a good design. This particular house is a one level on a slab, and they are just putting designs in the concrete (no flooring, I wish they were all this easy). I am breaking the house up into four zones. Part of the reason for doing that is the whole front of the house (east) is just about glass. I was trying to put the rooms with all the glass on there own zones. My thoughts are to design the house on constant circulation with an injection control and use the Tekmar t-stats with the floor sensors. Also I have a large room (40 x 20) that has all glass on one wall (40ft) and none on the other three. Should I try to layout my PEX so that I can adjust the flow rate? Thanks for any help in advance!

Bill NTSG

Try this

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Paul Pollets

A/C I presume??

Will you be installing A/C?

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Eddie Grierson

NO A/C

The homeowners do not want A/C. Were located in southern Maryland. The house is on the water. They are putting all the windows on the waterfront and counting on the breeze for cooling. I tried to talk them into A/C for humidity purposes. I've talked with Tekmar, they are sending me a control package recommendation.

Mike T., Swampeast MO

E Glass facing lake

My guess is that the common spaces face the lake (and maybe the MBR).

Solar gain in the a.m. (even reflecting off the water) shouldn't be too extreme because the sun's gonna' be quite far south in the winter (A/C isn't a total requirement so you're obviously pretty far north). Early spring & late fall are gonna' be weird regardless.

First: If only common space, keep to one zone. If common and MBR, you might have to use two zones depending on whether or not they cover the windows at night in the MBR.

Second: Use a modest (2-3 degree) nighttime setback in this zone until shortly after dawn.

Third: Install an air temp high-limit cut-off in a place CERTAIN to be rapidly affected by a.m. sun. Use this to shut down the slab circulation to this zone. Since a wall of glass (even insulated) tends to draw radiation from the body, the setting of the high-limit will take some tweaking.

Mike T., Swampeast MO

Just noticed S MD.

Since the don't want A/C they obviously plan on using operable windows to advantage and aren't too bothered with temperature fluctuation. Doesn't seem to strike me as owners wanting "set and forget" controls.

Not as far north as I was imagining but strategy should still work quite nicely.

Make certain there is an OUTSIDE CUTOFF.