Commercial HVAC questions, answered
Straight answers to the questions we actually get asked — about cost, timing, repair versus replacement, code, and what commercial HVAC work involves. If your question is not here, call 609-714-8280 and ask it.
Does Rooftop HVAC do residential work?
No. Commercial and industrial only. It is a deliberate limit rather than a gap — rooftop units, split systems and commercial ventilation are a different trade from home heating and cooling, and doing both well is harder than most companies that claim to admit.
How long has Bill Palombi been in commercial HVAC?
Over forty years, across commercial and industrial mechanical work and several established Delaware Valley contractors, before founding Rooftop HVAC. His experience spans service, installation and design.
Will you tell me if I should repair rather than replace?
Yes, and it costs us money to do it. Replacement is the larger job, so there is an obvious incentive to recommend it. Fifteen-year-old equipment with a failed compressor and R-22 in it is usually a replacement; a newer unit with one isolated failure usually is not.
How fast can you get to a commercial HVAC breakdown?
Response time depends on where the building is and what else is in the queue, but commercial emergencies are prioritized over routine work. Call rather than submitting a form if equipment is down — a phone call reaches a person and a form does not jump the queue. Our published response commitment is listed on the emergency page.
Do you work on equipment you did not install?
Yes, on an as needed, time and material basis. Most of our service work is on equipment installed by somebody else, often years ago and often with no documentation. Bring us the make and model if you have it and we will work from there; if you do not have it, we will find it on the unit.
What are the most common causes of commercial rooftop unit failure?
In rough order: dirty condenser and evaporator coils from deferred maintenance, failed contactors and capacitors, refrigerant leaks, belt and bearing failures on older units, control board faults, and economiser linkages that have seized. Most of these are preventable with scheduled maintenance.
Can you service multiple buildings under one arrangement?
Yes. Multi-site and portfolio work is a significant part of what we do. Tell us how many buildings and how many units per building and we will structure coverage and reporting around that rather than treating each site as a separate customer.
Will you tell me if a repair is not worth doing?
Yes, and we will tell you even when replacement is the bigger job for us. On a unit past fifteen years with a failed compressor, or R-22 equipment with a significant leak, putting money into the repair is usually throwing it away. You get the reasoning, not just the recommendation.
How much does commercial rooftop unit replacement cost?
Commercial RTU replacement typically runs from the low five figures for a small single-zone unit to well into six figures for large multi-unit projects. The main cost drivers are tonnage, whether a curb adapter is needed, crane access and staging, electrical service changes, and controls integration. We give a written number after a site survey rather than a range over the phone.
How long does a rooftop unit changeout take?
A straightforward single-unit changeout is usually a one-day crane and install once the equipment is on site. The longer part is lead time on the unit itself, which varies with tonnage and configuration. Multi-unit projects are staged so the building is never fully without conditioning.
Should I repair or replace my commercial rooftop unit?
Replacement usually makes sense when the unit is past roughly fifteen years, has had multiple significant repairs in the last two years, uses R-22 refrigerant, or has a failed compressor or heat exchanger. Repair usually makes sense on newer equipment with a single isolated failure. We will tell you when repair is the better call even though replacement is the bigger job.
Do I need a curb adapter when replacing a rooftop unit?
Usually yes, unless you are replacing with the identical model. Curb footprints changed as manufacturers redesigned cabinets, so a new unit rarely lands exactly on an older curb. A properly fabricated adapter is cheaper and far more reliable than modifying the roof structure.
Can you replace a rooftop unit without shutting down the building?
In most cases yes. Single-unit changeouts on multi-unit buildings only affect that zone. For buildings on one unit we schedule the crane outside operating hours, and where the process cannot tolerate any interruption we can arrange temporary cooling. Tell us the constraint up front and we will plan around it.
Are there rebates for high-efficiency commercial HVAC in New Jersey?
Yes. New Jersey utility and state energy programs offer incentives for qualifying high-efficiency commercial equipment, and they can meaningfully change the economics of a replacement. The programs and amounts change, so we confirm current eligibility as part of the proposal rather than quoting a figure that may be out of date.
What is HVAC design-build?
Design-build means one contract covers both the design of the mechanical system and its installation. The alternative, plan-and-spec, has an engineer design the system and then contractors bid to install what was drawn. Design-build tends to be faster and gives you one party accountable for whether the system actually works, rather than a design firm and an installer pointing at each other.
Is design-build cheaper than plan-and-spec?
Not always cheaper, but usually more predictable. Because the people who will install the system are involved while it is still being designed, buildability problems get caught on paper instead of in the field. Plan-and-spec can produce a lower bid number that grows through change orders once the drawings meet the actual building.
Do you do load calculations, or do you size from the old equipment?
We calculate. Sizing a replacement from the nameplate of what is already there just inherits whoever guessed last time, and buildings change use — a warehouse that added office space or a retail unit that became a restaurant has a different load than it did. Oversized equipment short-cycles, controls humidity badly and wears out faster.
Can you stamp drawings?
Sealed drawings require a licensed professional engineer. Where a project needs a PE seal we work with an engineer to produce it. For a great deal of commercial replacement and fit-out work no seal is required, and we can take it from survey through permit ourselves. We will tell you which situation you are in before you commit to anything.
Who pulls the permits?
We do, on the work we install. New Jersey work is permitted through the local construction office under the Uniform Construction Code, and mechanical permits are our responsibility on our scope.
At what point should I bring in an HVAC contractor?
Earlier than most people do. Once the architectural layout is roughed in there are still cheap decisions available — where equipment sits, how it gets serviced, whether the structure supports it, where the electrical service needs to land. After the drawings are finished those same decisions cost money.
New construction & fit-out
New construction & fit-out
Full detail on the new construction and fit-out page.
Do you bid mechanical scope from plans?
Yes. Send the drawings and specifications and we will price the mechanical scope, with exclusions stated plainly rather than buried. If we think the equipment schedule is wrong we will say so at bid time instead of writing a change order later.
How early should HVAC be involved in a fit-out?
As soon as the layout is roughed in. The decisions that cost nothing early — where the unit sits, how the duct main runs, where the electrical service lands, whether the roof structure carries the load — are the ones that cost real money after the drawings are sealed and the steel is up.
What is the lead time on commercial rooftop equipment?
It varies with tonnage and configuration and it has been the least predictable part of commercial mechanical work for several years now. Standard small-tonnage rooftop units are usually the shortest; large or custom configurations run considerably longer. We confirm current lead times when we quote rather than quoting from memory, because a stale lead time is worse than no lead time.
Can you work to a general contractor's schedule?
That is most of what this work is. We schedule around other trades, work to the GC's milestones, attend coordination meetings where they are held, and flag schedule risk — usually equipment lead time — early enough for it to be managed rather than absorbed.
What do you hand over at closeout?
Equipment submittals and cut sheets, as-installed documentation, manufacturer warranty registration, O&M manuals, and startup and commissioning records. If the project requires a specific closeout format, tell us at award and we will produce it in that format.
Do you handle tenant fit-outs where the base building system already exists?
Yes, and it is a common situation worth being careful about. A base building system was sized for a presumed use, and tenants frequently do not match it — a restaurant going into retail space, or a warehouse bay becoming office. We check whether the existing system can carry the new load before anyone assumes it can.
What is a make-up air unit and why do I need one?
A make-up air unit brings outside air into a building to replace air being exhausted out of it. Any building with significant exhaust — a commercial kitchen, a welding shop, a paint booth — is removing air continuously, and that air has to come back from somewhere. If there is no make-up air unit, it comes in through every gap in the building envelope, unconditioned and uncontrolled.
Why is the door to my restaurant hard to open?
That is almost always negative pressure, and it usually means your kitchen exhaust is pulling more air than your make-up air is supplying. It is worth taking seriously: the same imbalance makes hoods stop capturing properly, pulls conditioned air out of the dining room, can cause back-drafting on gas appliances, and drives heating and cooling costs up. It is a fixable balance problem.
How much ventilation does a commercial building need?
Minimum outdoor air rates are set by code and depend on how the space is used and how many people occupy it — an office, a classroom, a gym and a warehouse all have different requirements. New Jersey and Pennsylvania both build on the International Mechanical Code, which in turn draws on ASHRAE 62.1. The right number comes from a calculation for your space, not from a rule of thumb.
Can ventilation fix a hot warehouse?
Often, and usually for far less than cooling it. Warehouses stratify — heat collects at the roof while the occupied floor stays cooler — so the first questions are whether exhaust is moving that heat out and whether destratification fans are worth adding. Mechanical cooling for a large warehouse is an expensive answer to a question that ventilation sometimes answers cheaply.
Do you install commercial kitchen hood systems?
Yes — exhaust hoods, the make-up air that balances them, and the interlocks between the two. Kitchen ventilation is where imbalance shows up fastest, because the exhaust volumes are large and the consequences of getting it wrong are immediate.
What does it mean to balance a ventilation system?
Measuring what each fan, grille and diffuser is actually moving and adjusting until it matches design. It matters because a system can be installed exactly to drawing and still deliver the wrong air to the wrong places. Balancing is also the step most often skipped, which is why so many complaints about a room being stuffy turn out to be an airflow problem rather than an equipment one.
What should a commercial HVAC preventive maintenance agreement include?
At minimum: scheduled visits at a stated frequency, coil cleaning, filter changes, belt and bearing inspection, refrigerant charge verification, electrical connection checks, control and safety testing, condensate drain clearing, and a written report after each visit. It should also state response time for breakdowns and whether agreement holders get priority.
How often should commercial rooftop units be serviced?
Twice a year is the usual baseline — once before cooling season and once before heating season. Equipment in dirty environments such as restaurants, manufacturing or buildings near heavy traffic often needs quarterly attention, mostly because coils and filters load up far faster than in a clean office setting.
Does preventive maintenance actually save money?
It shifts spending from unplanned to planned, which is usually the bigger benefit. Dirty coils raise head pressure and energy use, deferred belt replacement takes out bearings, and a failed unit in July costs overtime plus lost building use. The arithmetic is less about the maintenance cost and more about avoiding the emergency.
Do maintenance customers get priority on emergency calls?
Yes. Agreement holders come first when several buildings are down at once. That prioritization is one of the main practical reasons to hold an agreement, alongside the fact that we already know your equipment before we arrive.
Can one agreement cover multiple buildings?
Yes. Multi-site coverage under a single agreement, with consolidated scheduling and reporting, is straightforward and is how most portfolio clients prefer to work.
Still have a question?
Ask a person. You will get the same answer you would get on the roof.