Why not just make some kind of fire-proof housing for 2x S1's? Creating a solution from scratch for a small market geared towards home heating would defeat the purpose of using older, less efficient miners that otherwise would have been tossed or sold at a fraction of the purchase price. Otherwise it would just make sense to buy something like Spondoolies or S3's which would come in at the same price point (or less).
S-3's would work if you find the correct fan's I am going to do a thread on s-3's with different fans vs the r-boxes
3 r-boxes and a rpi = 400 usd and 390gh power = 400 watts
1 s-3 plus the newer fans = 365 usd and 450gh power = 365watts
the s-3 has wifi with an antenna added if may be better but and here is your but I do not have a good enough fan as of today. so far every set of fans that works good enough to cool the s-3 is too loud.
I have this set coming to me on thurs:
http://www.amazon.com/Silverstone-Tek-Computer-Cooling-FHP-141/dp/B00A460TK6/ref=sr_1_1?ie=UTF8&qid=undefined&sr=8-1&keywords=silverstone+141