Jump to content

rjbrown2

Members
  • Posts

    61
  • Joined

  • Last visited

Personal Information

  • Location
    Georgia, USA
  • Occupation
    engineer

Recent Profile Visitors

771 profile views

rjbrown2's Achievements

Member

Member (3/5)

0

Reputation

  1. Are we in Handrail and Guardrail territory with this porch ? If I count correctly, we have six risers on the Stairs and the Elevation change of at least the Right side (as we view it) appears greater than 30 inches. <bb
  2. I believe I live in the same GA county as Jim. This WH was installed in 2007 in one of the corners of my basement. Notice the TPV drain line eventually goes vertical and ultimately has 4 (maybe 5 if there is one on the outside wall), 90 degree bends (one at the top out of sight) <bb
  3. Methane is not going to be the issue from an explosion in this set up. Methane (Natural Gas) is CH4 whose molecular weight is 16. Air has a molecular weight just over 28 (since it is mostly N2) The Methane is so much less dense than air it it will proceed straight out the vent. The culprit in any explosion in this rig would be Hydrogen Sulfide (H2S) whose molecular weight is 34. This gas is more dense than air and if it makes it up the vent to the fan 'junction' it could back spill into the bathroom. That being said, the explosion concentrations in air for H2S are from about 4.5 to 45%. This is so much higher than the allowable limits that if you started getting any serious H2S concentrations in the area, it would run you out from the irritation of your eyes, mucous membranes and lungs before there would be any explosion. Still wrong though. <bb
  4. "As a rare householdeR WHO still has a landline...." There, I fixed it for you. <bb
  5. Times change. A few decades ago we were having several near strikes per year taking out consumer electronics. Talked to the EMC (maybe there's the diff) and they installed a whole house surge suppressor for no extra charge or rent. Have no idea about the Joule rating though. GWTW I guess... <bb
  6. "It is named after Tarhe (whose nickname was "The Crane"), an 18th-century chief of the Wyandot Indian tribe." from Wikipedia. And "vee-(slight space) HICKLE" is a common Southern pronunciation of 'vehicle.' Don't need no 'Lantic Trench...<bb
  7. Marc: I said it clumsy. Since the skin depth is almost total at 60 Hz (current flows across the whole cross section) that means that conductor resistance is dominant like you said. The resistance of the squashed area is proportionally higher than the wire gauge. Is there (a) NEC citation(s) that back up the need to do anything ? It looks like ©rap, but absent a 'violation' what ? How do we justify it ?
  8. Actually when you cold work soft copper, you raise its tensile strength but lower its ductility. The problem it would face is vibration or frequent handling over some period could further work the interface between the soft and hardened sections leading to a brittle failure there. This seems low probability in a residential situation. An electrical question is that the skin depth of the current for 60Hz is significant. Reducing the cross section of the wire does what in near capacity conducting situations ? Seems like a hot spot is possible. Bare wire in an open area, OK ? Electrical experts please ?
  9. The 'owner' of a name is the authority on its pronunciation. For instance here in GA we have a county, no doubt named after the Great Rev War guy, DeKalb. We pronounce it dee-CAB county. People from up North (Illinois and Indiana) correct us and say it is pronounced 'dee-CAWLB' county. When in Indiana etc.., but here etc. We also have another county "Taliaferro" You would never guess - TOLLiver (rhymes with DOLL-iver)
  10. rjbrown2

    Puzzler

    I haven't done this in a long time and I'm sure there are easier ways to crank it out on the internet, but I got out my Psychrometric Chart E-7 that came with my Thermal Environmental Engineering text by Threlkeld (1960s era) Assume upfront that 2 ounces of water (about 0.125 lb H2O ) remain available after the cooling cycle to go back into the air continuously passing over the coil. Assume at the end of the cooling cycle the air is sea level atmospheric pressure, 78F and an R.H. of 45%. I locate that point on the Chart and that the W (lbs water/lb dry air ) is about 0.0096. If we assume an 1800 sq ft home the the air volume is about 1800 x 8 ft = 14400 ft^3 with 8 ft ceilings and no furniture. So let's guess that we have about 10,000 ft^3. Using the specific volume on the chart at our point and inverting it, we get about 0.073 lbs air/ft^3. This results in about 730 lbs of air in our house. The increase in W is then about 0.125 lb/730 lb = 0.0002 lbs H2O/lb air. That bumps the number from 0.0096 to 0.0098. I have to estimate on the Chart, but it looks like about a 1% increase in the RH depending how long it takes to evaporate and assuming we don't start another cooling cycle before that is accomplished. The biggest error possibility I immediately see is the air volume estimate in the house. If I'm low the effect is significantly lower than 1% and if I'm high it could come closer to 2% I don't know how sensitive we are to 1 or 2% differences in R.H.
  11. Marc I am familiar w/ Propane's refrigerant characteristics, but note its unlikely presence in consumer grade refrigeration equipment. I have experienced old SO2 refrigerators as I grew up in the 1950s with 'old' refrigerators
  12. Marc: From DURACOOL's bolierplate: "In the United States it is illegal to use a hydrocarbon refrigerant as a substitute for a Class I or Class II ODS refrigerant for any end use other than industrial process refrigeration systems, or retail food refrigerators and freezers (stand-alone units only)." I think what you are referring to is Propane fueled absorption refrigeration systems that generally use ammonia as the refrigerant.
  13. Could you make a life safety argument against an inward opening door ? A person who has become unconscious and is blocking the travel space for the hinged panels would make rescue difficult.
  14. I understand bends like that can slow the current down from about 0.9 the speed of light to about 0.8.... The cyclic bending associated with manufacturing and installation is so mild that the EC copper would almost never be work hardened enough to fail on the rebend. But, I would leave it alone too...
×
×
  • Create New...