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  • Users: jdmz
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  1. jdmz

    Ventilation Requirement IMC

    When replacing HVAC in an existing building that has no ventilation, is it required by code to add ventilation and exhaust? For example adding a VRF system to an old office building that currently has no ventilation and window AC units. Am I required to add ventilation and exhaust fans for...
  2. jdmz

    Glycol Corrections

    I use standard K factors for water so I apply a correction factor for the viscosity of glycol. I do account for the additional GPM required because of capacity derate, usually with equipment selection with the glycol conditions. So if I am getting a selection for coil with 35% glycol and they...
  3. jdmz

    Glycol Corrections

    Thanks so that means I would want to apply any correction factors to the head for viscosity prior to arriving at the ft h20 scheduled on the pump schedule. I have been doing it correctly then.
  4. jdmz

    Glycol Corrections

    When sizing a pump for a glycol system, I understand glycol has a pressure drop correction and well as a capacity correction as a function of the type, % volume glycol, and fluid temperature. The question is when I give a rep the head(ft) to size a pump, do I give him the corrected pressure...
  5. jdmz

    Supply Air Duct Condensation Temperature

    This is an existing building with an air handler that never had cooling. There are provisions (room in ahu) to add a cooling coil. The ahu is serving a gym, state, and a cafeteria. The reason why we evaluating not adding insulation is because it is extremely expensive.
  6. jdmz

    Supply Air Duct Condensation Temperature

    We are adding a cooling coil to an existing commercial VAV AHU without supply air duct insulation. I am trying to calculate the minimum duct temperature that is allowable while avoiding condensation forming on the duct surface. The duct is exposed in the space and some of it is in a plenum but...
  7. jdmz

    Kitchen Hood Exhaust Replacement

    This is a level 1 alteration, there are no architectural changes to the room. The other option I was thinking is just to repair the fan, that way it's not considered a replacement.
  8. jdmz

    Kitchen Hood Exhaust Replacement

    We are adding a new makeup air unit to a kitchen. The existing hood and exhaust is very old. Is it acceptable per code (IMC, IEBC) to replace the hood exhaust fan with one that matches existing airflow? The type of hood and the application it is being used for would require alot more CFM per...
  9. jdmz

    IECC 2021 Duct Insulation Requirements

    Thanks! I signed up for the ICC premium trial and looked at the commentary and it explained it. Too bad accessing the commentary is not free! Anyway to summarize insulation in conditioned spaces (other than for condensation purposes) isn't required at all per IECC commentary. The quoted...
  10. jdmz

    IECC 2021 Duct Insulation Requirements

    I am trying to interpret the meaning of a sentence in the C403.12.1 Duct and plenum insulation and sealing section of the 2021 IECC. "When located within a building envelope assembly, the duct or plenum shall be separated from building exterior or exempt spaces by not less than R-8 insulation...
  11. jdmz

    Refrigerant Equipment in Boiler Room

    Hello everyone. I have some VRF heat pumps in a boiler room that contains R-410a. From my understanding of ASHRAE 15, I am ok if the boilers are direct vented. Otherwise I will need a refrigerant monitor to interlock with the boilers to prevent the open flame creating phosphene gas from burning...
  12. jdmz

    2018 IMC - Historic Building Fire/Smoke Dampers

    I am designing a VRF system for a historic 3 story courthouse early 1900s and adding energy recovery ventilators to provide dedicated OA. The building is old and does not have life safety drawings or a fire alarm/sprinkler system. Most interior partitions is masonry. Is a life safety analysis...
  13. jdmz

    Understanding Continuous Loads

    Does the continuous load factor of 125% apply to motor loads and AC equipment? For example: I have a panel with: 1x AC unit, using MCA and MOP on nameplate 1x 2 hp motor, using 1.25*FLC 1x combination motor (2 hp and 1 hp motor), using 1.25*FLC largest motor + FLC smaller motor The three loads...
  14. jdmz

    Ventilation Exhaust Air under Door?

    EnergyProfessional - Yes, that is what I am asking. I am reading IMC 2021 and 601.2.1 mentions that the corridor can be used as "return air" plenum if 1 of the 5 conditions are met. However, in this case the air is not "return air", but "exhaust air" so I agree that this is probably illegal and...
  15. jdmz

    Ventilation Exhaust Air under Door?

    For offices, the requirement for OA is very small (10-30 cfm per office). I can't find in the code whether I can supply ventilation to the office using a diffuser and pull it under the door to the corridor where it is exhausted. The system is VRF with dedicated ERV providing ventilation to spaces.
  16. jdmz

    Trace 700 Oversizing

    How do you deal with the over-sizing of the cooling coil in Trace 700? Do you just assume the higher loads when making the selection? I am fixing cooling coil discharge temp at 55 F and Heating at 85F-90F. With a VAV reheat system, the program forces heating cfm to always be 30% (default)or...

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