Utilizing Solar Gain

Weezbo

you sir have a system that looks like it would be aminable to that stradgey. your installer knows how you ask them.

Joe_28

Utilizing Solar Gain

I'm wondering if anyone out there has experimented with utlizing solar gain from a radiant slab. My daughter and son-in-law moved into their new home/office this fall that has a 8x12' sliding french door on the south wall of the office. When the sun is shining on a 20 degree O.A.T. day, the slab will reach approx. 90 degrees where the sun is hitting.

The indoor air temperature in the office will reach 78-80 degrees with the stat set at 72. I took some readings this afternoon and by running the office loop circulator only, the return water temperature is 78 degrees. When running one of the circulators serving the north side of the house, the water returned at 72 degrees.

I'm wondering if it would be feasible to install a slab sensor to sense the solar gain and lock out the primary loop circulator and start the office zone circulator and a circulator in one of the north zones. I'm thinking this might pull the office temperature down and utilize the temperature gain the north areas of the house.

I've posted a couple of pics showing the effected floor area and the near boiler piping.

ggphysics

Floor finish

I was checking out your post and noticed the floor coloring/finish. I used the same acid staining process and have achieved the same coloring. The Kemiko sealer I used failed to adhere to the slab. I tried to remove the sealer with little luck. Which sealer was used on this floor?

Thanks
Glenn

Joe_28

ggphysics,
My dad had posted the message earlier about solar gain and asked me to respond to your question. We used acid stains made by Rare Earth Labs. They came concentrated and we had to mix them with water which I believe is different than the Kemiko products. They were then finished with a product called UV Super Seal - a high gloss solvent-based sealer. Before applying the sealer, my husband scrubbed and scrubbed and scrubbed the floors to remove any stain residue.

The finish came out great - the floor looks almost like marble, but they are not maintenance-free. The high gloss finish (and dark color) shows dirt and scratches, and my husband buffs them every couple months.

We also used another product on the concrete on our spiral stair steps - it is a matte finish sealer made by Schofield. It's very thin and takes lots of coats before it even shows up, but it adhered well too. Here's a couple of pics.

Weezbo

Excuse me*~/:)

perhaps i shold have focused upon the red potable water supply in the adjacent room.this is a minor technicality in calculating the flow required to shed the heat from the area. it may not be all that simple.

jerry scharf_2

doesn't look promising to me

Joe,

I would do a search, there was a long thread about this.

The problem is from that 90F surface, you have to move through 2 heat exchangers (the hot floor and the cold floor) both with some R value between the tube and the surface. There is a floor temp in the cold room that is needed to heat that room (from your load calcs.)

My guess is that not enough BTUs will be able to pass from the hot floor to the cold floor to get the floor temps under load as needed in the cold room.

I can walk you through this in more detail, but I didn't want to overwhelm you on the first response.

By the way, some cool photos of what looks like a really interesting house.

jerry

Rich W

slab

Solar water usually looks for a 20deg.diff. before it begins pumping-that's with no HX. If you use a differential temp. controller you could dump to a 55deg. garage floor. Just don't let the indoor slab get too cool.

jp_2

a little solar gain

I think what you are seeing is heating by floor reflection and window glass radiation. as you can see from the shadow areas the sun is not 'covering' much of the floor, thus the vast majorty of the floor is not gaining any heat that could be transfered.

best is to do a test. when you think solar gain is going to happen, shut the room down, then see how warm it is after the sun no longer shines in the room. if it cools quickly you have no solar floor gain to speak of.

Rich W

solar

Good call JP, The trees got in the way...

Unknown

if you really want to maximize your solar gain, step one is to get insulating window covers so you don't just lose that heat as soon as the sun goes down.

THEN think about recirculation strategies

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jp_2

not getting that much

you're losing that heat cause thats all you are getting!
look how big that floor is compared to the area covered by sunlight.