Utilizing Condenser Water to thaw walk bridge
Utilizing Condenser Water to thaw walk bridge
(OP)
A client has requested the feasability of diverting a 4" condenser water return main through a suspended crawlspace below an exterior pedestrian bridged crosswalk with the intent to force 85-90 deg. water through a manifold of fintubes (to provide radiant heat to slow paver freezing above)and back into the main building return. The area below the bridge is approx. 20ft x 30ft x 4FT clear. It currently is not a conditioned space. We could punch through the existing ceiling into this space however I am concerned whether an industrial fintube to fit this application even exists, and how much supplemental heat transfer can actually be made available? Location is Delaware (cold winters). There are re-insulation issues/freeze protection issues to also consider. Any input or suggestions would be appriciated.





RE: Utilizing Condenser Water to thaw walk bridge
RE: Utilizing Condenser Water to thaw walk bridge
How does the condenser duty match up against the hourly weather data?
Pump losses for pumping fluid through all this extra piping when it is above freezing would seem significant.
This would suggest looking at an isolated secondary loop for this.
My guess is that you will find that insufficient energy is available when needed, and that a dedicated direct fired snow melt system will be more viable.
RE: Utilizing Condenser Water to thaw walk bridge
RE: Utilizing Condenser Water to thaw walk bridge
RE: Utilizing Condenser Water to thaw walk bridge
RE: Utilizing Condenser Water to thaw walk bridge
RE: Utilizing Condenser Water to thaw walk bridge
Lots of data on the web about snow melt heat loads; I suspect in Delaware something like 110 BTU/ Sq Ft at design though I haven't researched it....But the grids that are normally employed have tubing at 6-12" centers, and that's cast in place...That spacing would correspond with using hot fluid temperatures of 130 to 160 deg.
As an energy justification in that climate, I would guess that the short duty proportion and the low temperature make it a bad investment...But that doesn't make it a bad project.
RE: Utilizing Condenser Water to thaw walk bridge
Sufficient temperature differentials for ice melting leverage is questionable, regardless. Pull-down ratios and response become very important. Electric heaters are probably the best option unless a central steam plant is nearby, and that would still encompass many issues. A heat exchange process with a pumped glycol - freeze-proof - mixture is prudent.
Also, please excuse the further comment, but energy codes will never trump life safety issues.