M & D Plumbing Heating and Air Conditioning has been serving Commack and the surrounding Suffolk County communities since 2018. We handle the full range of residential and commercial heating and cooling work, from a furnace that won't fire on a January morning to an AC unit struggling through a July heat wave. Our technicians show up ready to diagnose, repair, or replace, and every estimate is priced up front so you know exactly what you're looking at before any work begins. Quick response. Straight pricing. No surprises at the unit.
We cover repair, installation, replacement, and seasonal maintenance across all major heating and cooling systems. Whether you're a homeowner, a landlord managing several units, or a property manager overseeing a commercial building, we have the equipment knowledge and field experience to get the job done right.
We've served this area long enough to know what works, and what tends to break down when the seasons change on Long Island. We've serviced and replaced systems all over these neighborhoods, from split systems and heat pumps in newer construction to aging boilers and oil furnaces in homes that have been standing for decades. Homeowners, landlords, and commercial clients all come to us for the same reason: they want the job handled cleanly, without the runaround.
Our service list covers everything a heating and cooling system needs over its lifetime. AC repair and service, furnace repair and replacement, heat pump work, full system installation and replacement, thermostat and smart-control upgrades, ductwork repair and sealing, indoor air quality improvements, and pre-season tune-ups are all part of what we do day to day. Property managers especially appreciate having one reliable team to call for multiple units or buildings across the area. Give us a ring and we'll take care of it.
Comfort problems don't wait, and neither do we, especially when an air conditioner goes down in the middle of a Suffolk County summer. We diagnose and repair condenser and compressor issues, track down refrigerant leaks, and sort out airflow problems that leave some rooms cooler than others. If the system is past its useful life, we'll walk you through replacement options sized correctly for your home or building. An annual AC tune-up before the cooling season starts is the simplest way to avoid a breakdown when temperatures climb.
Long Island winters are cold enough that a furnace failure is never just an inconvenience. We service and repair gas furnaces, oil furnaces, and air handlers, including blower motor issues, ignition problems, and heat exchanger concerns. When a furnace has reached the end of its run, we handle full replacement with equipment that fits your home's layout and heating load. A pre-season tune-up each fall keeps the system ready before the cold arrives and catches small problems before they become expensive ones.
Heat pumps handle both heating and cooling in a single system, which makes them a practical fit for Long Island's climate where you need real performance on both ends of the calendar. We repair heat pumps that have stopped heating or cooling effectively, and we install new systems for homeowners looking to upgrade or replace aging equipment. A properly installed heat pump improves efficiency and gives you year-round comfort control without running two separate systems.
A thermostat that isn't calibrated correctly or communicating properly with your system wastes energy and leaves rooms uncomfortable. We install and replace standard thermostats, programmable models, and smart controls that let you manage your home's temperature from your phone. A well-matched control system ties directly into your overall comfort and keeps your heating and cooling equipment running at the right times.
Leaky or damaged ductwork is one of the most common causes of uneven temperatures and higher-than-expected energy bills. We inspect, repair, and seal duct systems so that conditioned air actually reaches the rooms it's supposed to reach. When ducts are poorly connected, crushed, or deteriorating, the heating and cooling equipment works harder than it needs to, shortening its lifespan and driving up costs. Fixing the duct system is often the first step toward solving comfort complaints that have gone unresolved for years.
Suffolk County summers bring humidity that can make indoor spaces feel stuffy and create conditions where dust, allergens, and mold thrive. We install whole-house air filtration systems, humidifiers, and dehumidifiers that work alongside your existing HVAC equipment to improve what you're breathing every day. These are not standalone add-ons. They integrate directly into the system so the air moving through your home is cleaner and better controlled year-round.
Suffolk County's housing stock runs the full range, from newer construction with modern forced-air systems to homes built decades ago around boilers, radiators, and oil tanks. Cold winters, humid summers, and a high share of older non-ducted homes create a specific set of heating and cooling needs that we handle regularly. The three services below come up constantly in this area, and we've built real experience around each one.
Many homes in Commack and across Suffolk County heat with boilers, either steam or hot-water systems connected to cast-iron radiators. These systems are durable, but they need regular attention to run safely and efficiently. A boiler service visit typically covers burner inspection and cleaning, pressure and temperature checks, zone valve and circulator pump testing, and a full safety review of the controls and relief valve. When a boiler reaches the end of its service life, we handle full replacement with a properly sized hydronic system. Work is performed by qualified HVAC technicians who understand the specific demands of older hydronic installations in this region.
The Northeast, including Long Island, carries one of the highest concentrations of oil-heated homes in the country. Many Commack homeowners are moving away from oil, either to natural gas or to a heat pump system, to reduce fuel costs and simplify long-term maintenance. We handle the equipment side of that conversion: removing the old oil unit and installing the new heating system correctly. We speak only to the heating equipment itself. Other trades handle their respective connections, and we coordinate the installation so the new system performs the way it should from day one.
Older homes and additions throughout Commack often lack the ductwork needed for a central forced-air system. A ductless mini-split is the practical answer. We install single-zone and multi-zone systems that deliver both heating and cooling without requiring any new duct runs. Mini-splits are also a strong fit for garages, finished basements, sunrooms, and any space that doesn't connect cleanly to an existing system. The result is precise comfort control in the spaces that need it, with energy efficiency that older window units simply can't match.
When the heat goes out in February or the AC fails on the hottest week of the summer, waiting days for a technician is not an option. We offer same-day service for heating and cooling emergencies, and we work to get a qualified technician to your door as quickly as possible. Clear communication from the first call to the final test is how we handle every emergency visit, so you're never left wondering what's happening or what it will cost.
We serve both residential and commercial customers for emergency calls. A failed rooftop unit at a small business and a furnace that won't start in a rental property both get the same fast attention. Quick to arrive. Careful with your home. Tidy when we leave.
Call for a quote or to schedule same-day service at (631) 623-9591.
We treat your home and its system the way we would our own. That means arriving on time, explaining what we find, and completing the work cleanly without unnecessary upsells. For homeowners, that translates to reliable repairs and installations you can count on season after season. A spring tune-up before the cooling season and a fall tune-up before the heating season are the two most effective things you can do to protect your investment and avoid emergency calls.
Property managers and landlords have a different set of concerns: fast response, clear documentation, and consistent quality across multiple units or locations. We work with commercial clients and property management teams throughout the area on everything from routine seasonal maintenance to full system replacements in multi-unit buildings. We're ready to get your heating and cooling running again.
What a heating or cooling job costs depends on what the job actually involves. A straightforward repair, a full system replacement, and a ductless mini-split installation are three very different scopes of work, and the cost reflects the equipment, the labor, and the specifics of your home or building. We don't quote vague ranges over the phone. We look at the system, assess what's needed, and give you no-pressure estimates, priced up front, before any work begins.
If you're weighing a repair against a replacement, we'll give you the information you need to make that decision without pressure in either direction. Call for a quote at (631) 623-9591 and we'll schedule a visit to take a look.
Staying ahead of HVAC problems keeps your home comfortable and keeps repair costs manageable over time. A spring tune-up gets your AC system ready before the first hot stretch, covering coil cleaning, refrigerant levels, electrical connections, and airflow checks. A fall tune-up does the same for your heating system, whether that's a furnace, a heat pump, or a boiler, so you're not discovering a problem on the first cold night of the season.
Our technicians know the homes and systems in this area, and a tune-up visit is also a chance to catch developing issues before they turn into emergency calls. Replacing a worn part during a scheduled visit costs far less than an after-hours emergency repair. Scheduling a pre-season tune-up is one of the simplest decisions a homeowner or property manager can make. We're ready to get your heating and cooling running again.
We serve Commack as our home base and work throughout the surrounding communities in Suffolk County. Nearby towns we cover regularly include Hauppauge, Smithtown, Kings Park, Dix Hills, Huntington, Melville, Brentwood, and Nesconset. Whether you're a few blocks from our service area or a town over, we can get a technician to you for repairs, installations, or seasonal maintenance.
If you're not sure whether we cover your address, call us. We're happy to confirm and get you scheduled.
Common warning signs include unusual noises from the boiler or pipes, uneven heat across rooms, a loss of pressure that keeps recurring, and visible corrosion or leaks around the unit. If your boiler is leaving some zones cold or running constantly without reaching temperature, a diagnostic visit is the right next step.
We handle the equipment side of the conversion: removing the old oil-fired unit and installing the new heating system correctly. Other trades handle their respective connections, and we coordinate the installation so the new system performs as expected from day one. We walk you through the options before any work begins so the decision makes sense for your home and budget.
Ductless mini-splits are a strong choice for homes without existing ductwork, finished additions, sunrooms, and spaces that never reach the right temperature. Installation does not require new duct runs, which makes it cleaner and faster than retrofitting a central forced-air system. We design single-zone and multi-zone setups that give you independent comfort control in the spaces that need it.
A no-heat situation in winter, a no-cool situation during a heat wave, and a system that has shut down entirely and will not respond are all emergencies. If your home or building is at a temperature that is unsafe or seriously uncomfortable, call us at (631) 623-9591 for same-day service.
A spring AC tune-up covers coil cleaning, refrigerant level checks, electrical connection inspection, and airflow testing. A fall heating tune-up covers the burner or heat exchanger, blower components, safety controls, and an overall system check. Both visits are designed to catch developing problems before they turn into emergency calls.
The decision comes down to the age of the system, the cost of the repair relative to the cost of replacement, and how efficiently the existing equipment is running. We give you the information you need to make that call without pressure in either direction. If a repair makes sense, we will say so; if replacement is the better investment, we will explain why.
We assess the existing equipment and your home's heating and cooling load, recommend a correctly sized replacement system, give you a clear estimate before any work begins, and schedule the installation at a time that works for you. Work is performed by qualified HVAC technicians who handle the removal of the old unit and the installation and testing of the new one.
Uneven temperatures are usually caused by ductwork problems, an undersized or oversized system, or airflow restrictions in a particular zone. We inspect the duct system and the equipment to find the root cause. In homes without ductwork, a ductless mini-split for the problem area is often the most effective solution.
We inspect the evaporator coil, the blower motor and wheel, the filter and filter housing, the drain pan and condensate line, and the electrical connections and control board. On a heating system, we also check the heat exchanger, ignition components, and safety controls. The goal is a complete picture of how the system is performing, not just a look at the obvious problem.
Short-cycling is often caused by a dirty filter restricting airflow, an overheating heat exchanger triggering a safety shutoff, or a faulty flame sensor or ignition component. Cold air from a running furnace usually points to an ignition failure, a tripped limit switch, or a gas supply issue. A diagnostic visit pinpoints the cause so the repair addresses the actual problem.
M & D Plumbing Heating and Air Conditioning is locally owned and personally accountable to every customer we serve. When you call, you reach someone who knows this area and can get your service scheduled without delay. Our technicians arrive prepared, communicate clearly, and leave the work site clean. No-pressure estimates, priced up front, are standard on every job.
Call (631) 623-9591 to schedule service, request an estimate, or get same-day help when you need it fast. Quick response. Straight pricing. No surprises at the unit.
We handle the full range of residential and commercial heating and cooling work in Commack and across Suffolk County, from a same-day repair call to a full system replacement. Every job is performed by qualified HVAC technicians who know Long Island's homes, its climate, and the equipment that runs in them. The table below outlines what each service covers, who it fits best, and a practical note to help you decide where to start. Call us at (631) 623-9591 and we will walk you through the right option for your situation.
| System Service | What's Included | Best Suited For | Things to Know |
|---|---|---|---|
| Ductless Mini-Split Installation | Single-zone and multi-zone setups, Heating and cooling in one system, No ductwork required | Older homes without ducts, additions, sunrooms, or rooms that never reach the right temperature | Installation is typically cleaner and faster than retrofitting a full central system into an existing home |
| Emergency HVAC Service | Same-day and after-hours availability, No-heat and no-cool response, Honest diagnosis before any repair begins | Anyone whose heat or air conditioning has stopped working and cannot wait | We are available every day from 8:30 AM to 9:30 PM, including weekends |
| Heat Pump Repair and Service | Refrigerant leak checks, Airflow and control system testing, Heating and cooling mode diagnostics | Homes running a heat pump for year-round comfort on a single system | Heat pumps handle both seasons, so a problem in one mode often affects the other |
| Oil-to-Gas and Heat Pump Conversion | Removal of oil-fired equipment, Gas or heat pump system installation, Guidance on efficiency and operating costs | Homeowners ready to move off oil heat and reduce dependence on fuel deliveries | The Northeast carries more oil-heated homes than anywhere else in the country; conversion work is a regular part of what we do here |
| Thermostat and Smart-Control Installation | Programmable and smart thermostat installation, Wiring and settings configuration, Compatibility check with existing equipment | Anyone with an erratic system or who wants better control over comfort and energy use | A properly configured smart thermostat can meaningfully reduce energy use over time |
| Full System Installation and ReplacementMost Popular | Central AC and furnace replacement, Heat pump system installation, Energy-efficiency upgrade options | Homeowners whose system is aging, failing repeatedly, or no longer cost-effective to repair | We provide clear pricing before any work begins so you know the full cost up front |
| Boiler and Hydronic Heating Service | Hot-water baseboard and steam systems, Pressure and noise diagnostics, Radiant heat repair and maintenance | Older Long Island homes running boilers, radiators, or radiant floor heat | Many Suffolk County homes have boiler systems that have run for decades and benefit from regular service |
| Seasonal Maintenance and Tune-Ups | Spring and fall system tune-ups, Key component checks and safety confirmation, Pre-season performance review | Any homeowner or property manager who wants to avoid unexpected breakdowns | Systems that get regular maintenance last longer, break down less often, and cost less to operate |
| Heating and Furnace Repair | All makes and models, Blower and air handler service, Heat exchanger diagnostics | Any home or business that has lost heat or is getting inconsistent warmth | Emergency furnace repair is available when you cannot wait for a scheduled visit |
| Ductwork Repair and Sealing | Leak detection and sealing, Damaged section repair or replacement, Airflow balancing | Homes with uneven temperatures, high energy bills, or rooms that never feel right | Leaky ducts are one of the most common and overlooked causes of comfort and efficiency problems |
| AC Repair and Service | Diagnostic and refrigerant checks, Condenser and coil inspection, Airflow and cycling troubleshooting | Homeowners with a unit blowing warm air, cycling too often, or not keeping up | Same-day availability is often possible for urgent calls during the cooling season |
| Indoor Air Quality and Air Filtration | Whole-home air purifiers and scrubbers, Air filtration system installation, Whole-home humidifier installation | Families concerned about allergens, dust, dry air, or what the system is circulating | Long Island homes run their systems hard through humid summers and dry winters, making air quality equipment a practical upgrade |
How do I know whether to repair or replace my heating or cooling system?
Age and repair history are the two biggest factors. A system under ten years old that has been maintained and has a straightforward problem is usually worth repairing. When a system is older than fifteen years, has needed multiple repairs in recent seasons, or the repair cost approaches half the price of a replacement, replacement often makes more financial sense. We walk through both options with you honestly and give you clear pricing on each so you can make the call with full information.
What are the signs that my air conditioner or furnace may need to be replaced soon?
For an air conditioner, watch for rising energy bills without a change in usage, frequent repair calls in the same season, uneven cooling across the home, or a system that runs constantly without reaching the set temperature. For a furnace, warning signs include unusual noises, short cycling, cold spots in the home, or a heat exchanger that a technician has flagged as cracked or compromised. Neither list is exhaustive, but any of those patterns is worth a diagnostic visit.
How often should I schedule maintenance or a tune-up?
Once a year per system is the standard recommendation, and timing matters. For a central air system, a spring tune-up before the cooling season starts is ideal. For a furnace or boiler, a fall visit before you need heat is the right window. If you run a heat pump year-round, one visit in spring and one in fall covers both modes. Regular maintenance is the single most reliable way to avoid unexpected breakdowns and keep operating costs in check.
Transparent Upfront Pricing
We give you clear pricing before any work begins, whether it is a repair call or a full system replacement. No hidden charges, no surprise totals at the end of the job.
Why is one room in my home always hotter or colder than the rest?
Uneven temperatures usually point to one of a few causes: leaky or undersized ductwork, a zoning issue, a dirty filter restricting airflow, or equipment that is not sized correctly for the home. Ductless mini-splits can solve the problem in rooms that have never been comfortable, and duct sealing or repair often resolves it in homes with existing ductwork. A diagnostic visit gives us a clear picture of what is actually happening before we recommend a fix.
What does a seasonal tune-up actually cover?
A tune-up visit covers the key mechanical and electrical components of the system, confirms safe and efficient operation, checks refrigerant levels on cooling equipment, inspects the heat exchanger on a furnace, and tests controls and safety switches. We also look at the filter, the blower, and the coils. If something looks like it could become a problem before the next season, we flag it and explain what we found. The goal is to catch small issues before they turn into expensive repairs.
Can I get same-day service if my heat or air conditioning stops working?
Same-day availability is often possible, especially if you call early in the day. We offer emergency service for no-heat and no-cool situations throughout Commack and the surrounding area every day from 8:30 AM to 9:30 PM, including weekends. Call us at (631) 623-9591 and we will ask a few quick questions about the system and get a technician scheduled as fast as we can.
Same-Day and Emergency Availability
We are available every day from 8:30 AM to 9:30 PM, including weekends, and same-day service is often possible for urgent heating and cooling calls throughout Commack and Suffolk County.
What causes a system to short-cycle, and is it serious?
Short-cycling means the system turns on, runs briefly, shuts off, and repeats the cycle without completing a full heating or cooling run. It can be caused by an oversized system, a dirty filter blocking airflow, a refrigerant problem, a faulty thermostat, or a control board issue. It is worth addressing promptly because short-cycling puts extra wear on the compressor and other components and raises energy costs. A diagnostic visit identifies the root cause so the fix addresses the actual problem.
How do ductwork leaks affect my energy bills and comfort?
Leaky ducts allow conditioned air to escape into unconditioned spaces like attics, crawl spaces, or wall cavities before it ever reaches the rooms you are trying to heat or cool. The system works harder to compensate, energy bills go up, and some rooms never reach the right temperature. Sealing and repairing ductwork is one of the more cost-effective improvements a home can get, and the comfort difference is often noticeable right away.
Experienced With Older and Newer Systems
Long Island's housing stock ranges from decades-old boiler systems to newer heat pump installations, and our technicians are comfortable working on all of it.
What is involved in switching from oil heat to a heat pump or gas system?
The conversion involves removing the existing oil-fired equipment and installing a new gas furnace or heat pump system in its place. We handle the heating equipment side of the job. We walk you through the options based on your home's layout, existing ductwork, and what makes the most sense for your long-term operating costs. Many Suffolk County homeowners are making this move to reduce dependence on fuel deliveries and take advantage of more efficient technology.
Do I need to be home when the technician comes out?
For most service calls and installations, yes, an adult should be present. The technician needs access to the equipment, may need to ask questions about what the system has been doing, and will want to walk you through the findings and pricing before starting any work. If your situation is complicated, call us and we will work out the logistics together.
How does your pricing work, and will the estimate change once the technician arrives?
A technician assesses the system, explains what they found, and gives you clear pricing before any work begins. If the scope changes once we are on-site, we talk to you about it before moving forward. There are no hidden charges and no surprise totals at the end of a job. No-pressure estimates, priced up front, are how we handle every call, whether it is a repair visit or a full system replacement.
Call (631) 623-9591 and we will help you figure out exactly what your system needs and get you on the schedule.
(631) 623-9591