I am not aware of any. It seems like it is really a matter of how cold the conditions are. If you had a sprinkler system of uprights where the uprights are the only piping dead ends then you might expect the water density difference between cold at sprinkler and warm at the circulating piping to drive a circulation flow in the upright. Maybe the odd spot right at water freezing where the densities flip back and forth is a complication but perhaps that would not be an issue as long as the circulating pipe is very warm compared to the sprinkler. You would insulate all the piping except for the sprinkler. That might work provided conditions are not so cold that more heat escapes the sprinkler's seat than what is transferred from the circulating pipe. Ice would be at the seat first, probably dislodging the seat. What should be invented is a flower bud like protective cap fitted over the sprinkler that expands to fall away when heated to say 135 F. That cap would provide the neede d freeze exposure protection during other times. The rest of the system would be easily maintained warm with a jacket of insulation and circulated fluid.
Modern electrical heat tracing is self limiting. The power consumed in these is a function of temperature. The heating system has to use energy regardless of its source. What would you have powering the pumps needed to circulate the water in the piping? What would you have providing the heat to transfer to this system? New Zealand seems like a good place for wind and geothermal energy. All energy used to do something ultimately results in heat. Here is an application where what we want is the heat. Lots of ways to do this come to mind, but I think that special sprinkler freeze cap might be a handy. How the listed electrical tracing systems maintain that sprinkler seat from freezing when installed by your average causal electrician is something I find hard to believe. Perhaps it is the tape's self limiting aspect that provides the needed extra heat at the critical location. I bet their installation detail must wrap the tape at least once all around the sprinkler's exposed bas e or the last fitting's outlet shoulder. Allan Seidel St. Louis, MO On Jun 13, 2013, at 5:02 AM, Nicky Marshall <[email protected]> wrote > > Is anybody aware of approved systems for freeze prevention of sprinkler > pipework that involves circulating water within pipework? > We are aware of dry systems, anti-freeze systems, heat tracing. > A dry system requires additional water due to area increase - a tank would be > needed. > Anti freeze has not got very good press lately and approved products are > expensive. > Heat tracing does not seem like a very energy efficient system. > There are circulating systems for domestic applications and internet searches > show several patents for such systems for sprinklers, but I cannot find > actual products. > > Thanks > Nicky Marshall > Protech Design > New Zealand > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
