latent heat

slowlearner

i'm reading dan's book on heating and wondering if i've had a eureka moment. ( please consider my nickname )



dan notes that latent heat is carried by the steam "train."  my previous and naive "understanding" was that the steam itself heated the radiator, when in actuality it is the condensation of the steam and the subequent release of latent heat that serves as the heat source.



am i on the right track?

malp

correct!

The condensate and steam are the same temperature, so the heat's not coming from something cooling like in a hot water system where hot water enters the radiator and cool water leaves. The heat comes from the phase change from steam to water. 

R Mannino

Eureka

You've had an epiphany!

slowlearner

more info

thanks for the quick replies.



really enjoying this book.  wish car manuals were as clearly written. 



i am a newly hired maintenance director at a school with an antique steam system and am determined to get everything in order.   lots of old steam traps, no main venting, etc. 



running about twenty grand in heating costs per season.  current plumbing company has the pressuretrol at 4-5 psig.  lots of water hammer, cold/hot radiators, leaking vents.  they also installed Macon "1-10" valves at the inlets of each radiator to control the steam into the radiators.  seems like the controls should be at the vent end.



unfortunately,  they don't seem to have a clue about how to repair things once and for all and they are not shy about billing for their services.    the serviceman today spent 8 hours taking an inventory of all the steam traps and radiator vents for rebuilding.   at $100/hour that hurts.  told him about dan's seminar in long island city on jan 6 but that suggestion went in one ear and out the other with no change of pressure.



so glad to have access to this site!



thanks again.

Empire_2

Ahh DannieaSOn....:-)

Latent heat is a MUCH misunderstood topic and although very interesting, can be boring to tell BUT: I'll give it a shot:-).

• "Change of state"  Handy to know.  We'll go with WATER.  Although you could choose gold, copper, brick, glass, etc...  we have to acknowledge that if a substance is heated or cooled  and it's temperature rises or falls, this is called "SENSABLE HEAT".  Each substance has a title called SHC or "specific heat capacity", and water's specific heat just happens to be 1.0-SHC.  As measured in BTU's ,1 lb. of water heated 1 degree F= 1 BTU  (British thermal unit).  Exmp:  To increase the temp of 1 lb of water @42* to 203*, How many BTU's are required?
• Diff/ 161* X 1.0  specific weight of water,(in this case) = 161 BTU's
  
  
  
  Let's take 210* water to 212*,.....How much?  2* X (1.0) = 2 BTU's  @ 1lb.
  
  
  
  OK 212* water to 212* STEAM??  Is that possible?  OK 1/2 btu???   Nope
  
  
  
  The amount of heat required to raise 1 lb. water from 212*f  to 1 lb steam @ 212*f is............
  
  
  
  
  
  
  
  977BTU's. "This is called Latent Heat" .........I am confident that I explained this correctly and I hope it helps.  Waite till next time, when I'll tell Ya, that I can get water to......oh say 220*f without it boiling.   It's all about the pressure.
  
  
  
  PEACE & MERRY CHRISTMAS TO ALL,. AND TO ALL A GOOD NIGHT..:-)
  
  
  
  Mike T.