Comfort Design airflow Space air distribution Outside air proportion
Indoor Air Quality (IAQ) Indoor air pollution Material outgassing Particulates Ventilation Infiltration, natural, and mechanical Fresh air proportion required by code.
HVAC Safety Loose hair, jewelry, wristbands, clothing Situational awareness Disconnect OFF Lock-out Tag-out Safety glasses Right tool for the job
VOM Basics Alternating current (AC) Direct current (DC) Continuity
VOM Basics Measuring voltage – Select type of power and range If unsure select highest range Measure voltage to ground Checking fuses – Select Continuity (diode symbol) Place probes at each end of the fuse If the fuse is good, then tone and reading 0
Controls Straight Cooling Red Thermostat, Air Handler, Condenser Yellow Thermostat, Condenser White Thermostat, Air Handler Green Thermostat, Air Handler
Controls Heat Pump Red Thermostat, Air Handler, Condenser Yellow Thermostat, Condenser White Thermostat, Air Handler, Condenser Green Thermostat, Air Handler Orange Thermostat, Condenser Black Thermostat, Air Handler, Condenser
Problems A/C not working (Not running ) Power Fuses at disconnect 24VAC to control board Control board fuse 24VAC to thermostat Power at thermostat terminals
Problems 24VAC at thermostat terminals R to C Y to C in cooling W to C in heating G to C in fan mode If no C terminal read between R and appropriate terminal (Y, W, G). If there is power at the terminal there will be no reading.
Problems A/C not working (running) Airflow temperature Filters Coils Condenser operation
Problems Condenser troubleshooting Power Low voltage terminals Discharge air temperature Liquid line temperature (cooling)
Problems Space too hot/cold (A/C working) Check for airflow Filters Dampers Controls
Problems “Smudging” – Dirty filters Dirty coil Particle entrainment Squealing On start-up - Belts slipping While operating – Belts too tight
Ventilation air Required by code ASHRAE 62.1-2007 Requirements vary by occupancy Amount for each system found in the balancing report.
Outside Air Direct measurement Temperature method Must be 15F – 20F difference between outside air and return air temps. Formula:(MA – RA)/(OA – RA) Where:MA = Mixed air temp OA = Outside air temp RA = Return air temp
Outside Air Temperature method in action Conditions:Outside air temp: 30F Return air temp: 70F Mixed air temp: 64F Formula:(64 – 70)/(30 – 70) = 0.15 or 15% outside air.
Diffuser Vanes Control diffusion and mixing in the space. Improper adjustment can lead to stagnant zones and drafty areas in the space. Usually set vanes at 45 degree angle from the center on sidewall diffusers.
Balancing Dampers Located in ductwork prior to grilles. Usually located immediately prior to grille or at ductwork branch. If little to no flow at grille: Verify that damper is open Ensure that damper handle position corresponds to damper position
Fire Dampers Located in ductwork at fire-rated partitions. If there is no airflow to a space, check the fire dampers. Visual inspection through access doors in ductwork.
Controls Ensure that the thermostat is level. Electronic thermostats programmed correctly.
Air Handling Equipment Change filters every month Orient filters correctly More often in dirty environments (laundry) Pre-filters in dirty environments Clean coils annually Keep fans clean Exhaust fans
Air Handling Equipment Make sure that belts are tight and aligned Recommended ½” deflection Pulleys should be in alignment Grip-notch belts may solve slipping problems Ensure that drain lines are clear Drain pans slanted toward drain line Install float switches Wired between transformer and control board
PTAC Package Terminal Air Conditioner Power Line fuse – 15A buss fuse 24VAC to control board Control board trouble code Power at control board terminals 3A buss fuse No power from board – replace Compressor makes ‘chugging’ noise – dying
Property Refrigeration Walk-in cooler and freezer Under-counter reach-in Display coolers Not running - Power Fuses Running - Coils Discharge air temperature Liquid line temperature
Property Refrigeration Guest room refrigerators Power Coil Loaded Defrost