HVAC questions
Our technicians respond to calls involving burners, blowers, piping and controls. This section covers what homeowners can safely inspect and what requires our technicians to restore proper operation of heating and cooling equipment.
Anything not covered here, ask Cupe Mechanical HVAC directly on (833) 540-9225.
Heating Equipment Questions
Why does my furnace ignite then shut off quickly?
Short cycling often starts when a limit switch detects restricted airflow across the heat exchanger. Homeowners can replace a dirty filter and confirm supply and return vents remain open. If the blower runs but the burner still cycles, our technicians check the inducer motor, pressure switch tubing and rollout switch for proper operation.
What causes low water pressure in a boiler system?
Pressure drops usually trace to an automatic fill valve set too low or a leak at a fitting or zone valve. Homeowners should read the gauge when the system is cold and note any visible drips at valves or baseboard ends. Cupe Mechanical HVAC technicians isolate the circuit, test the expansion tank and restore correct fill pressure.
How do I know if my furnace heat exchanger has cracked?
A cracked exchanger may produce a sulfur smell or carbon monoxide alarm during operation. Homeowners must never attempt internal inspection. Our technicians remove the burner assembly, use mirrors and lights to examine every cell and measure combustion gas levels before deciding on repair or replacement.
Why is the boiler circulating pump making noise?
Air trapped in the impeller or worn bearings creates grinding or whining. Homeowners can bleed air from the highest purge valve while the pump runs on low speed. Persistent noise requires our technicians to check system flow rate, verify pump orientation and measure amp draw against nameplate values.
Cooling System Questions
What makes an AC unit freeze up on the evaporator coil?
Low refrigerant charge, dirty filters or blower speed set too low reduce airflow and drop coil temperature below freezing. Homeowners should change the filter and confirm the fan setting is on auto. Cupe Mechanical HVAC technicians measure superheat and subcooling to locate the exact cause before adding refrigerant.
How does a heat pump reversing valve fail?
The valve sticks when the solenoid coil weakens or debris blocks the slide. Homeowners hear the compressor run without a change in airflow direction between heating and cooling. Our technicians apply 24-volt power directly to the coil, listen for the click and replace the valve if the slide does not move.
Why does my ductless mini-split lose cooling after a few hours?
Line-set insulation gaps allow heat gain and the outdoor unit may enter high-pressure lockout. Homeowners can clear leaves from the condenser fins. Cupe Mechanical HVAC technicians recover refrigerant, check flare nuts for proper torque, add new insulation and verify EEV operation.
What causes high static pressure in residential ductwork?
Collapsed flex, closed dampers or undersized returns raise static above 0.5 inches water column. Homeowners can open all dampers and remove obstructions at registers. Our technicians insert a manometer at the blower door, map pressure drops and recommend duct modifications when readings stay elevated.
Maintenance and Installation Questions
How often should air filters be changed in commercial buildings?
Filter change intervals depend on MERV rating and occupancy load. A 2-inch pleated filter in a busy office typically needs replacement every four to six weeks. Cupe Mechanical HVAC technicians record pressure drop across the filter rack and adjust the schedule based on actual readings rather than calendar dates.
What is checked during preventive HVAC maintenance?
Technicians measure blower amperage, clean condensate drains, tighten electrical connections, test safety switches and verify combustion efficiency on gas appliances. Homeowners can keep the area around indoor and outdoor units clear of storage. Cupe Mechanical HVAC records each reading and compares values to previous visits.
Why does new ductwork need proper sealing at every joint?
Leaks at seams and connections allow conditioned air to escape into attics or crawl spaces and pull in unconditioned air. Homeowners should never attempt taping pressurized ducts. Our technicians use mastic and mesh on all joints, then test total leakage with a duct blaster before finishing.
What size considerations apply to ductless mini-split installation?
Correct sizing requires a Manual J load calculation for each zone rather than square footage alone. Homeowners can note which rooms stay uncomfortable. Cupe Mechanical HVAC measures wall construction, window orientation and internal gains before selecting indoor and outdoor unit capacities that match the calculated loads.