hotbox solar-thermal basement heater

[mountain]

Hello all

I'm new to this forum, and am happy to find. I've jsut completed my 1st solar-thermal project, documented in the following link.

http://www.mountainelectric.ca/hotbox/

My challenge was to build something effective that harvests energy at the maximum ratio of kWh/$cost

I'd love to get some feedback from more experienced forum members, as well as to read about other similar collectors.

M

[Mike90250]

Great project, and grand idea. If it gets a high WAF (Wife Acceptance Factor) that's even better !! 2 comments.

1 Do you have any problems with RADON gas in your area?

2) Styrofoam eventually compresses from weight. When its shot, you may want to consider a different foam board that is also fire-resistant, polyisocyanurate insulation board. Usually a light brown color.


And peruse this fellows site/write up about his solar shes heat collector:

http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/solarshed.htm

[mountain]

Q1 "Do you have any problems with RADON gas in your area?"

A : No radon gas in the immediate area where we live, but the potential is recognized in the BC building code, where a continuous layer of 6mm poly is required within the lowest floor layer. Only concrete is allowed for basement & crawl-space floors, but that is because of hunta-virus. I considered a concrete bottom slab for the hotbox, but rejected it on the basis of high thermal conductivity to the ground. During construction I took considerable care to ensure the hotbox is 100% insect & rodent-proof

Q2) "Styrofoam eventually compresses from weight. When its shot, you may want to consider a different foam board that is also fire-resistant, polyisocyanurate insulation board. Usually a light brown color."

A: I used the blue SM high-density styrofoam available at the local building supply. At present I have not added any thermal-mass (a wall of stacked limestone), and the hotbox works well enough. When I do, I will place the rock not directly on the hotbox floor, but on a supporting timber that transfers the weight to the foundation.
The hotbox surfaces are fire-proof materials (drywall interior & hardie-board exterior), 100% sealed. So, should the pile of rocks burst into flame....

I checked out your solar shed & liked it. Good stuff!

M

[mountain]

1st month results

The hot-box has been harvesting solar energy for 1 month now, and here are the results. Alas, it has been untypically cloudy with rain/snow, with only a few beautiful blue days, which is unusual for the East Kootenays in BC.

The 5-day span Nov 2-6 were actually very sunny & the hotbox ran many hot hours. Unfortunately a software bug in the energy measurement section of the controller, made me throw out the data from those 5 days. Fixed now.

M

[Mike90250]

Nice, every bit helps cut back on the propane bill