Air Filters
Evaporator and Condenser Coils
Fan Blades and Motors
Condensate Drain Lines
Ductwork
Grilles and Registers
Refrigerant Lines
Outdoor & Indoor Units
Thermostat
Refrigerant Leaks
Compressor Issues
Fan Motor Problems
Thermostat Malfunctions
Blower Motor Issues
Capacitor Failures
Electrical Problems
Condenser Coil Problems
Evaporator Coil Issues
Expansion Valve Problems
Ductwork Issues
Heat Exchanger Problems
Water Leaks
Control Board Issues
Airflow Problems
Commercial HVAC installation, from load calculation to commissioning
Commercial HVAC installation is the decision a building lives with for the next decade and longer, and most of what settles how it performs happens before the equipment is ordered. Two items move the price further than the machine does: rigging the unit into place, and whether the building's electrical service can carry it. Both get answered at the survey, along with the load, the roof, the duct and the gas supply.
- Load calculated, not copied off the old unit
- Electrical service and phase checked at survey
- Permitted and presented for inspection
- Off-hour and phased installs
One unit, one trunk, two zones. Where the unit sits, where the air has to reach and what the building can feed it are the three questions a survey answers before any equipment is priced.
What is inside a commercial installation
Two proposals for the same building can differ by a wide margin because one prices all twelve of these and the other prices a machine and a day of labor. Read a quote against the list and the gap usually explains itself. All of it sits inside our commercial HVAC service.
Survey and load calculation
The building measured, not the old unit's capacity copied.
System selection
Type, capacity, staging and heat source chosen against that load.
Roof, curb and structure
What the deck carries, and whether the curb matches the new unit.
Electrical service and phase
Voltage, phase, spare capacity, conductor sizing, disconnect.
Gas supply
Pipe sizing, meter capacity, shutoff and a leak check at connection.
Refrigerant lines
On splits: sized for the run, brazed under nitrogen, insulated.
Duct and distribution
Trunk, branches, curb transitions, sealing, dampers, registers.
Controls and thermostats
Staged, configured, sensors sited where they read the room.
Condensate and drainage
Pan, trap and drain sized and pitched for their section.
Permits and inspections
Filed, booked, and left in a state an inspector can sign.
Startup and commissioning
Charge and airflow verified running, then balanced and documented.
How a commercial system is sized properly
A commercial load calculation is arithmetic on a building, not a rule of thumb on a floor area. Two units of the same tonnage can be right and badly wrong in buildings of identical size, because what fills a commercial load is rarely the walls.
What the calculation takes in
- Heat loss through the envelope on a design winter day: walls, roof, slab and glass
- Heat gain in summer through the same envelope, plus solar load on the glass and the roof
- Infiltration, and on a commercial building the pressure the exhaust fans put it under
- Occupancy at peak, counted as both sensible heat and moisture
- Lighting and equipment load: a cook line, refrigerated cases rejecting heat into the sales floor, a server closet, retail display lighting
- The outside air the space has to be given for its use and headcount, heated or cooled on its way in
That last item separates commercial work from residential. Ventilation air arrives at whatever the weather is doing and the equipment conditions all of it, so in a restaurant or a gym it can be a larger share of the cooling load than the building itself.
Guessing shows up in two directions. Undersized equipment runs continuously through July, holds temperature only when the building is quiet, and never gets the off-cycle a compressor is designed around, so it uses up its running hours years early. On a design day it simply cannot hold the space.
Oversizing is the more common error because it feels safe. A unit with more capacity than the space calls for satisfies the thermostat quickly and stops, so the coil never runs long enough to condense much water out of the air. The room reads cool and feels damp, the compressor takes the wear of the extra starts, and the duct sized for the old machine now has to carry more air than it was built for.
Which is why a replacement is not automatically a like for like order. Buildings change use, tenants subdivide them, lighting loads have fallen and kitchen loads have risen. What was correct in 2004 is the starting point for the conversation, not the answer to it.
Which architecture belongs in your building
Six architectures cover almost everything we are asked to install. Which of them your building can take is settled by three physical facts: whether there is a roof opening and the structure to carry equipment above it, whether the building has usable duct or none at all, and how many separately controlled spaces the layout has now as against when it was built.
The choice also commits you to something for as long as the building has it: how the equipment gets reached for service, what a future change-out costs to lift, and whether one failure takes out a room or a floor.
Packaged rooftop unit
The default on single story retail, restaurants and warehouses: the roof is the only spare real estate and one cabinet handles both seasons. It commits you to roof access for every service visit and a lift for every future change-out.
Split system
Where there is no roof opening, no structure for a curb, or the space sits above another tenant. The indoor half needs a mechanical room and a condensate route, and the two halves have to be a matched pair to perform as rated.
Ductless multi-split
For buildings carved into small tenancies, additions with nowhere to run duct, and rooms that need cooling when the rest of the building does not. Each head is its own control, which suits uneven hours and odd loads.
Zoned duct system
One air source, motorized dampers and zone thermostats, for a sales floor and a back office with nothing in common. Cheaper than a second unit, and it works only when the duct and the bypass are designed for it rather than added later.
Heat pump
Heating and cooling from one machine, with no gas connection to it. On Long Island a commercial heat pump is planned with a supplemental heat source for the coldest stretch, and the electrical service has to carry both.
Make-up air
Not comfort equipment and not optional. Where a hood pulls air out of the building, something has to put the same volume back, and on restaurant work it is specified alongside the cooling, not after it.
Three-phase power, the part that is underestimated most
More commercial installations stall on electrical service than on equipment, and it is the one item an owner almost never has an answer for when the first quote is requested.
Commercial equipment above the smallest capacities is built for three-phase power. Three-phase motors start and run without the capacitors and start components a single-phase motor needs, they run smoother, and they draw less current per leg for the same work, which is why compressors and larger blowers are built around it. Plenty of older Main Street buildings on Long Island were only ever given single-phase service, and nothing about the storefront tells you which one you have.
Voltage is a separate question from phase. Commercial equipment is commonly built for 208 or 230 volts, or for 460, and a unit ordered against the wrong one does not simply run less well. The data plate also carries the minimum circuit ampacity and the maximum overcurrent protection, and those two figures, not a rule of thumb, size the conductors and the breaker feeding it.
Rotation matters at startup. A scroll compressor wired with the phases in the wrong order turns backwards: it makes an unmistakable noise, pumps nothing, and damages itself if it is left running. Checking rotation is a two-minute job on install day and a warranty argument when it is skipped.
What the survey establishes
What service the building has and whether it is single or three phase. How large that service is and how much of it the rest of the building already uses. Free panel space and the condition of what is in it. The voltage to order the equipment at. Whether a disconnect can be reused. And where the feed has to run, since a rooftop run and a ground-level run are different pieces of work.
Where the building needs more service than it has, that becomes its own item on its own schedule, because a service upgrade belongs to the utility and moves at the utility's pace. Found at survey it is a line in the proposal. Found on install day it is a stalled job with a crane already on the lot.
The duct, the controls and the water
Duct, controls and condensate are usually inherited from whoever installed the last system, and all three decide whether the building feels the money you spent on the new one.
The duct you already have
Existing duct is normally reused and has to be checked against the airflow the new unit is rated to move. A blower delivers rated airflow only at or below the external static pressure it is rated for, so duct that was tight for the old machine is worse with a bigger one. Static pressure gets read across the system before a change-out is called finished, and belt-driven blowers are set to the duct they are actually feeding.
Controls and staging
Commercial units stage: two stages of cooling, two of heat, an economizer pulling in outside air when the weather will do the work for you. None of that runs correctly on a thermostat wired for a single-stage machine, and an economizer nobody set up is a damper that stays shut for the life of the unit. Sensor placement gets the same attention, because one thermostat in direct sun keeps a whole floor uncomfortable.
Condensate and drainage
An air conditioner makes water all summer, and the drain has to move it against the pressure inside the cabinet. On a draw-through section the coil sits in negative pressure, so the trap has to be deep enough to overcome it or the pan simply fills and overflows. On a blow-through section the trap is what stops air pushing out of the drain instead. Wrong trap for the section, and it is ceiling tiles in August.
Project phase and permit tracker
Ten phases from first visit to handover. Select one to see what happens, what we need from you, where the permit and inspection steps fall, and how much of it your business feels. There are no durations here on purpose: scope, permit turnaround, equipment lead time and the utility set those, and they go in your proposal once the scope is fixed.
Phase 1. Site survey
A technician measures the building and records the envelope, the glass and the occupancy, along with roof access, curb condition, duct routes, the panel and the gas meter. Any one of those can change what should be installed, so they are all captured on the same visit.
How the space is used and at what hours, headcount at its busiest, and access to the roof, the panel and the mechanical space.
None at this phase.
One visit inside normal hours. Nothing stops.
Phase 2. Load calculation and system selection
Loads are calculated from the survey and equipment selected against them: type, capacity, staging, heat source, controls and the airflow the duct has to carry.
Anything that changes the load: added cooking equipment, a tenant fit-out, more headcount, longer hours.
None yet, though the selection decides what gets filed later.
None. This happens at our end.
Phase 3. Proposal, scope and equipment order
The scope in writing: equipment, what is included, what is excluded, and any building work needed before the unit can run. That is the document to hold beside any other quote. Equipment lead time is a real item on the schedule.
A signature from whoever can commit for the property, and any landlord condition to design around.
None. The signed scope is what the filing is drawn from.
None on site.
Phase 4. Structural, electrical and gas coordination
The parts of the job that belong to other people start early: the deck and the curb, the electrical service, gas pipe and meter capacity, and where a crane can legally set up.
Landlord contact, your electric service details, and permission to survey the roof and the panel.
A utility application for a service upgrade starts here. It runs on the utility's timetable, which is longer than ours.
Short visits only.
Phase 5. Permit filing and approvals
Drawings and applications go to the department with jurisdiction over the address, which on Long Island means the town, or the incorporated village where the building sits in one. Landlord approvals go in alongside, and nothing is booked on the roof until the permit position is known.
An owner's signature and the property details the department asks for. That is the whole of your involvement.
The mechanical permit is filed here, and the electrical work registered with an inspection agency where the municipality uses one.
None on site. This phase usually sets the calendar for the project.
Phase 6. Delivery, staging and access
Equipment arrives and is staged where it can be reached on the day, and the route in is protected before anything crosses it. Parking, the lift set-up area and the exclusion zone under the boom are agreed with the building and anyone sharing the lot.
Somewhere to stage, and a delivery window that misses your own deliveries.
Lot or street occupancy permission where a crane needs it, which some villages handle separately.
Part of a day of your access route and some parking.
Phase 7. Removal, rigging and set
The old unit is isolated, its refrigerant recovered by an EPA Section 608 certified technician and documented, then rigged off the roof. The curb is prepared or an adapter fitted, the new unit set, flashing made good. The lift and the curb detail are covered on rooftop unit installation.
The lot clear at the agreed hour and somebody reachable by phone.
The permit is on site from this point on.
The phase you feel. No conditioning while the old unit is down and the new one is not yet running, which is why lifts are booked before opening or on a closed day.
Phase 8. Connections and rough inspection
Power, gas, duct transitions, condensate, controls, and on a split system the refrigerant lines, every one of them landed to the data plate figures and pressure tested before anything is fired.
Panel access and a short agreed window with the power off in one area.
A rough inspection falls here where the municipality calls for one, before anything is concealed.
Localized. One planned power interruption, agreed in advance.
Phase 9. Startup, charge and balancing
Safeties proved, the charge verified against superheat and subcooling with the system running rather than topped off by eye, manifold pressure set, and temperature rise measured against the data plate.
Nothing. This phase is what separates a unit that is installed from a unit that is working.
None, though these readings are what the final inspection and the warranty record rest on.
The system is running. Technicians on the roof and at the thermostats for part of a day.
Phase 10. Final inspection and handover
The inspection is met, the sign off is chased to a close, and the settings, filter sizes and labeling are written down for whoever runs the building.
Someone for the walkthrough, ideally whoever is in the building when it next misbehaves.
Final mechanical inspection, plus the electrical certificate where the municipality issues one. You get the paperwork, not a promise of it.
An hour of somebody's time, and the building back to you.
What actually decides the number
We quote after seeing the building, because the number comes from the building rather than from the equipment list. These six items are what move it, so two proposals can be read against each other.
Capacity and unit count
What the calculated load calls for, and whether one machine covers it or the building needs several because the spaces cannot share one.
What the curb and roof allow
Whether the existing curb takes an adapter or has to be rebuilt, what the deck carries, and what roofing work the penetration and flashing involve.
The lift
Crane or boom truck, how far it has to reach, whether there is legal space to set up, and whether the lot has to be closed to do it.
Electrical and gas
A circuit and a disconnect if the service carries the unit. A panel, a feeder or a utility service upgrade if it does not. Gas piping where the meter or the pipe run is undersized.
Duct, controls and ventilation
Duct modification where the airflow has changed, a control package that matches a staged unit, and any outside air or make-up air in the same scope.
Removal, permits and hours
Refrigerant recovery and disposal of the old unit, permit and inspection costs, and whether the work runs inside your trading hours or outside them.
Two of those six move a total further than the rest together: rigging, and electrical service work. Knowing which of them you are facing is most of what you need before taking the project to a landlord or a lender, and it is what the survey settles. If the existing unit still has life in it we will say so, and a repair is the cheaper answer for that year.
Permitting and inspection readiness
Every town in Suffolk County and every incorporated village runs its own building department, with its own forms, its own drawing requirements and its own habits about what it wants to see before it schedules an inspector. Nassau is the same picture across a different set of counters. Handling that is our job: the filings, the drawings and the appointments are part of the installation.
Permit turnaround and inspector availability belong to the municipality. We can tell you what was filed and when, and have the work ready the day an inspector can come. We cannot move the appointment, and a contractor who promises otherwise is guessing at your expense.
What an inspector is looking at
Clearances around the unit and a service path that can be used. A disconnect within sight and conductors matching the data plate. Gas piping supported, with its shutoff. Condensate terminated somewhere acceptable. Penetrations sealed, firestopped where they cross rated construction. Curb, flashing and roof detail left weathertight. Labeling that lets the next person work on it safely.
None of it is exotic, and all of it is checked before the inspector is called rather than after.
Off-hour and phased work
Commercial installation is scheduled around trading, which is why so much of it happens overnight, before opening, or on whichever day a business is quietest. Restaurants tend to get a Sunday night into Monday, retail the hours before the doors open, an office building a weekend.
On a site with several units the work is phased one unit at a time, so the building is never entirely without conditioning and the disruption arrives in pieces you can plan around. Across more than one shift, we leave the building with working heat or cooling at the end of each one wherever the system allows it.
The two fixed points are the lift and the inspection. A crane needs daylight, a legal set-up and a clear swing, and an inspector comes when the department sends one. Everything either side of those is arranged around your hours, and you are told in advance which phases you will notice.
Handover, warranty and the years that follow
Warranty registration is filed at our end so the equipment is on the manufacturer's books from day one. Terms come from the manufacturer and differ by equipment and by component, so what you get from us is the actual coverage for the machine you bought, in writing.
The company that installed the system is the company that answers when it stops: ordinary service during the week, emergency response around the clock every day of the year, typically on site within 90 minutes across Suffolk and Nassau County. We already hold the startup readings, which is usually the shortest route to an answer.
What warranty does not do
It covers parts that fail. It does not cover a system that was never set up correctly, and it does not cover a condenser coil that has not been cleaned since the day it was set. Manufacturers generally require documented service, which makes planned maintenance part of keeping the coverage rather than an extra.
Where an installation runs alongside refrigeration work in the same building, the electrical is worth planning once rather than twice.
Installation questions we are asked most
Can a new unit go on our existing curb?
Often, and it is what keeps a change-out to a lift and a connection instead of a roofing job. It depends on whether the new unit's footprint and its supply and return openings line up with what is there, which they rarely do exactly across manufacturers or model generations. A curb adapter bridges the difference. The curb's condition and what the deck carries are checked at the survey, not on the morning of the lift.
Do we need a three-phase service upgrade?
That depends on the equipment the load calls for and on what the building already has. Smaller capacities come in single phase, so in a modest space the answer is sometimes to select around the service you have. Above that, three phase is what the equipment is built for, and the upgrade becomes part of the project on the utility's schedule. The survey settles which of the two you are in before you commit to anything.
Should we replace all our rooftop units at once or one at a time?
Condition and age decide it more than budget does. Replacing together means one permit, one mobilization, one lift day and controls that match. One at a time spreads the cost and keeps more of the building running through each phase. We will tell you what each unit has left rather than quoting the whole roof by default.