Kentucky Cold water input will I freeze?

Discussion in 'Maintenance and Troubleshooting' started by ReallyOddJobs, Nov 16, 2016.

  1. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I assume you meant density decrease below 39F? Water is getting lighter below 39F. I should be pretty much a linear function, weather you heat it up or cool it down. But I agree that the 32F limit is reached quickly and you have no room for error. The surface area is simply to small.
     
  2. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Yes - increase...my bad.

    As to density changes being being linear with temperature...actually no, from what I've browsed the density of water, though it peaks at 39*F / 4*C, is nearly unchanged between 32*F - 50*F (0*C - 10*C), varying only about 0.01% within that entire temperature range.

    At more, shall I say "civilized" water temperatures, (such as those more likely encountered OUTSIDE a beer glass in Jacksonville, Florida vs Buffalo, NY), the density change with temperature becomes a fair bit more pronounced. In the 60,70,80*F range the density change is on the order of 0.01% per degree F...still not much, but 10x what's available in in the temperature range surrounding 39*F.

    Stated another way, water heated several degrees by a Slim Jim or any other submerged heat exchanger in cooling mode at ~ room temps +/- has 10x the buoyancy lifting it away than water cooled several degrees by that same heat exchanger from 39*F.

    We've wandered away from the OPs point, but staving off icing of a marginal submerged heat exchanger might require forced convection, such as via a submerged fountain pump (high flow, very low Delta P). Something like this is done in Mid-Atlantic climates as an alternative to hauling boats for the winter - pumps sitting on the bottom in a marine drive (presumably 39*F - ish) water upward to the surface, staving off damaging ice formation next to boats. I imagine that works in Maryland, but not Minnesota (or, for that matter, Buffalo).

    Water frozen into ice has A LOT more buoyancy (10 full percentage points)...I think awhile back Mark posted some pictures of a pond loop having been lifted to the surface by icing then becoming entombed in very very cold surface ice for the balance of a heating season then characterized by an awful lot of aux heat or firewood...bummer.

    Winter is swinging into high gear here in North Florida...what with several morning lows cracking the 50*F mark now so far we are starting to get those "emergency" no heat calls....probably won't be able to go outside in short pants until noon or so...oh the burdens we must sometimes bear!
     

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