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  1. RandomUserName

    Ventilation Question

    In regards to IMC 403.2.2: Say you have a building with two spaces; an office and a single bathroom. The bathroom has a single fixture and needs 50 CFM of exhaust; the office space has 5 occupants and is 416 SQ. FT. needing 50 CFM of outside air (5*5+416*0.06 = 50). Does the unit that serves...
  2. RandomUserName

    Ventilation for food processing plant

    Just a thought off the top of my head: 62.1 only requires ventilating spaces that are "occupiable spaces"; the definition of that excluding "those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are only occupied occasionally and for...
  3. RandomUserName

    DOAS Chilled Beam no way to dehumidify

    Thanks for following up! This has been a fun one. "When return air humidity [...]" What return air? I thought this was a DOAS + ACB system? If so there is no return air, only supply air from the DOAS and exhaust air. Even assuming they meant exhaust air humidity, they way that is worded...
  4. RandomUserName

    Exhaust In line Booster Fan ... Fan Interaction

    dbill74, System we will tie-in to is on the first floor and goes up to the 7th floor where it is discharge via upblast centrifugal fan. 3025 CFM @ 1.25" w.c. We are literally the second to last branch on the system as the furthest away. Turn this into a fun homework problem and for now assume...
  5. RandomUserName

    Exhaust In line Booster Fan ... Fan Interaction

    BronYrAur, That was my gut reaction as well and I showing that the contractor is to provide a balance damper on the discharge side of the booster fan but still upstream of the common node. Let's run with that thought and make some numbers up with it! Let's tie-in the branch in question to the...
  6. RandomUserName

    Exhaust In line Booster Fan ... Fan Interaction

    That does not help answer by question at all. What do you believe happens at that connection point once the booster fan is turned on?
  7. RandomUserName

    Exhaust In line Booster Fan ... Fan Interaction

    I am having trouble conceptualizing the following: I have a piece of equipment that needs to be exhausted. The piece of equipment has a pressure drop through it of 0.25" w.c. at the required flow of 25 CFM. I would like to tie-in the exhaust to the general building exhaust. Problem is, I am...
  8. RandomUserName

    for a regular house HVAC system (Fu

    Correct. On an evaporator wet coils (in cooling) have much higher pressure drops than dry coils (in heating). As an example: I am currently looking at the cut sheet for a basic 4 ton nominal goodman residential unitary split DC evaporator (CAPF4860). At 1600 CFM the coil has a dry pressure drop...
  9. RandomUserName

    DOAS Chilled Beam no way to dehumidify

    If design numbers are as you said (DOAS SAT 55F), then the air will not remove the entire latent load; humidity will rise. The reason I had come to the conclusion that DOAS SAT was 50F was because the latent load (3450 BTU/hr) closely matched what 360 CFM could remove between 50F DB / 95% RH...
  10. RandomUserName

    DOAS Chilled Beam no way to dehumidify

    GMcD - Took all of 15 minutes ... at my rate it would probably only be $20! [lol]
  11. RandomUserName

    Heat Remove by Ventilation.

    As everyone else has said: You cannot make a room colder using warmer air.
  12. RandomUserName

    DOAS Chilled Beam no way to dehumidify

    Assume: Design Space Conditions: 75°F DB / 50% RH Primary Air Conditions: 50°F DB / 95% RH Primary Air flow: 360 cfm Latent load: 30 students * (115 BTU/hr/student) = 3450 BTU/hr Humidity Ratio in Space = 0.0092 lbw/lb Humidity Ratio of Primary Air = 0.0072 lbw/lb [Qlat (BTU/hr)] = [Airflow...
  13. RandomUserName

    Carrier's Hap - Airflow rates in summary report

    Just a quick double check: in the air system properties, on the sizing data tab, in zone sizing, you have correctly set your zone airflow sizing method and space airflow sizing method?
  14. RandomUserName

    Calculation for 100% fresh unit

    Carefully. Wouldn't want to screw up would ya!
  15. RandomUserName

    primary/secondary - Secondary pump location with respect to the bridge.

    Secondary pumps should always discharge into secondary circuits away from common piping. Doing so ensures an increase in secondary circuit pressure over that established in the common piping by the primary pump. The common piping can be considered as the compression tank “No pressure change...
  16. RandomUserName

    Bathhouse HVAC

    Certainly seems doable. If they are budget conscious I would expect they will be OK with HV part of HVAC. I feel like the AC part is gonna kill em. Gut reaction. What region is this building located in the world? EDIT: Note that in my state if you are doing any new or replacement MEP work in a...
  17. RandomUserName

    Server room

    That would be the conservative way to do it. How often do you think those CPUs are computing at 100% load? There is some diversity here. See "HVAC Equations, Data, and Rules of Thumb" by Bell and Angel.
  18. RandomUserName

    SS/GI connection

    dbill74, Tough I cannot answer for afa13's reasoning for switching materials, I have seen many exhaust duct work systems that use aluminum or stainless steel duct work for the showers, then switch galvanized steel once they are comfortable the combined mixed air streams (usually air from a...
  19. RandomUserName

    Hvac system in hot and humid climate

    cry22, Understanding your point of view, would you not agree that one could select some of the more modern RTUs that have modulating compressors/ condenser fans and humidity sensors to not only maintain (and match) sensible loads but latent loads as well? Would this marginal cost (from say a...
  20. RandomUserName

    Room Pressure

    I agree with urgross, drazen, and composite pro. So here is an interesting question with an answer based in experience: If you are pressurizing a room positive (lets say a typical amount is 0.03-0.07" w.c.), how much "less" return air do you return in rooms for balancing? I have been taught...

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