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  • Users: zekeman
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  1. zekeman

    Does anybobody have (or a link to)

    Does anybobody have (or a link to) the transient solution to the heatup of a hot water tank? For simplicity, assume the system adiabatic with the tank water stagnant and it's initial temperature T1. The heat exchanger area is A and the overall conductance is U. The heat source is hot water...
  2. zekeman

    need help on a pc board

    Don't know if this is right forum. But, here goes Does anybody here have a circuit diagram or can tell me where to get one of a PC board in the receiver control unit of a Casablanca fan with a wall mounted W32 controller. My problem is that this "world class" fan has inferior electronics and...
  3. zekeman

    power sharing 2 generators

    I would like to hook up 2 generators (1000W and 3000W) to share power in proportion to the size. I would appreciate any suggestions, caveats, etc. in this regard.
  4. zekeman

    HVAC software

    Looking for reliable HVAC software for load and sizing calculations. Appreciate any info
  5. zekeman

    dynamic response spring mass system

    I have a design problem that I can do numerically but I'm looking for a more elegant method. Here goes: A spring, S is interposed between 2 masses (M-S-m aligned vertically) and compressed by the gravity of the much larger mass, M which sits on top. The smaller mass, m which is much smaller...
  6. zekeman

    Puzzle

    Defyiing law of angular momentum? Here is a fun puzzle for you purists. How is it that a kid sitting on a swing starting at rest can, without any help, always cause the swing to oscillate? Please explain.
  7. zekeman

    dynamic equations for solenoid

    I have an application to move a .33lb mass 1 inch in and out within 35 msec so I am thinking linear solenoid which wouild require a dynamic analysis which I probably can develop but if someone out there knows of a source I would very much appreciate hearing about it. I tried Google and came up...
  8. zekeman

    reglar vs hight test gas

    Is it cost effective to use regular gas on an engine that is rated for high test? Is there any documentation around? Thank you.
  9. zekeman

    Efficient hot water heating system

    I know that there must be a hotwater heating system out there that measures the outside temp and inside setpoint and then controls the boiler cycling and duty cycle to maintain the room temperature, allowing the circ pump to work continuously. Who makes one and what are the pros and cons? I...
  10. zekeman

    Heating and cooling program

    Can anyone recommend decent software at a reasonable price to do residential heating and cooling load calculations. I don't do them very often but without a program they ate too timeconsuming. Thank you.
  11. zekeman

    thermal efficiency

    I was wondering how the tech who measures my "efficiency" comes up with it based only on stack temp and CO2. I made the calculation based on complete combustion and X excess air (absenting sulphur and nitrous oxides), as follows. From data I obtained, #2 oil is approximately 85% carbon and 12 %...
  12. zekeman

    esp

    I have a problem with this ESP. It is the external static pressure, external to what? If the mfr of the furnace wants you to exclude the pressure drop across the airhandler, and I picture a simplified flow system that has a series of algebraic static drops: 1) across the blower,a-b (actually a...
  13. zekeman

    Replace w/ high SEER heatpump or AC economics

    Can somebody show me why I should buy a SEER14 HP if I presently use a SEER 9 and my electric rate is $0.16/KWH and the average ambient outside temp during summer is 80 for 4 months (location southern CT). Or should I just consider staight A/C and forget the heatpump. If possible please point me...
  14. zekeman

    bleed resistor across start cap

    Can you think of any reason other than personnel safety for a bleed resistor across a starting cap on a single phase motor. If you tell me it protects the relay contacts, show me why.

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