Where Comfort and Integrity meet Lifestyle
Delmarva's full-service mechanical contractor since the 1950s — 60+ years, 40+ technicians, eight trades, available around the clock. A local company with national resources.
One call covers all eight trades
Commercial and residential. HVAC, plumbing, electrical, refrigeration, indoor air quality, installations, maintenance, and sheet metal — one contractor, Delmarva-wide.
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Commercial HVAC & Refrigeration
PM agreements, emergency repairs, and major installs — HVAC, electrical, controls, and plumbing for commercial, healthcare, and light-industrial facilities across Delmarva. Call for a quote.
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Residential Heating & Cooling
Furnace down at midnight? AC quit in July? Our 24/7 emergency line is 302-629-9400. We also offer Home Comfort Plans to keep your system running before it fails.
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Service & Maintenance
Proactive maintenance costs far less than emergency repairs. Ask about our Home Comfort Plans (residential) and Commercial Building Systems Plans — the most cost-effective way to protect your equipment.
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Indoor Air Quality
Breathe cleaner air at home or work. GPS Needlepoint ionization eliminates up to 99% of airborne pathogens including COVID. Asthma and allergy certified filtration available.
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Installations
Replace an aging system and save up to 50% on energy costs. Authorized American Standard dealer for residential. Commercial rooftops, VRF, ductless, and specialized equipment handled end-to-end.
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Plumbing
Leaks, backflow testing, hydro-jetting, free in-home water testing, water heater service, and Plumbing Comfort Plans — one crew handles it all. Call 302-629-9400.
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Electrical
Generators, VFDs, switchgear, LED retrofits, and building automation — our licensed electricians serve commercial, industrial, and institutional facilities. Request a quote today.
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Sheet Metal Fabrication
Precision-fabricated ductwork, plenums, fittings, and transitions — cut and formed in Seaford for exact fit. When quality matters the first time, talk to our sheet metal team.
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Insights by National
Our biggest differentiator — exclusively available through National HVAC.
Most contractors leave after a service call — you get a bill and a guess at what was done. National HVAC gives you proof. Insights by National is our cloud-based documentation platform, built to keep you completely informed of every visit to your home or business.
When our technicians are on site, they photograph, video, and note every aspect of the work — on a cloud platform that keeps your service teams and you in sync in real time.
Every visit builds your equipment history. If a different tech visits next time, a quick photo of the data plate pulls up service manuals and prior Insights — so your systems get serviced faster and smarter every time.
After each call you receive a summary with a link to preview our work — step into your mechanical room, up on your roof, or into your crawlspace from your phone. See the condition of your equipment and the work performed. This transparency is exclusively available through Insights by National.
See the work we doThe work speaks for itself
Selected commercial and residential mechanical projects across the Delmarva region.
A local company with national resources
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AMERICAN STANDARD DEALER
Authorized American Standard dealer — rated #1 in customer satisfaction. Ask about high-efficiency systems that save up to 50% on energy costs.
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PART OF SERVICE LOGIC
The largest privately-owned HVAC service company in the U.S.
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WESTERN SUSSEX CHAMBER OF COMMERCE
Active member serving the Delmarva business community.
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WELLS FARGO FINANCING
Up to 60 months, no interest on qualifying equipment. Don't let budget delay a system replacement — ask our team today.
SERVING NOTABLE DELMARVA CLIENTS
K&L Microwave WMDT TV Johnny Janosik Crossroads Community Church
Trusted for decades
Facility managers and CEOs keep calling us back — here's why.
The key to K&L Microwave's success over the years is planning and observing every avenue possible. National HVAC has helped K&L Microwave accomplish every task from minor PM service to major specialty machine repair. National HVAC has been very resourceful for K&L Microwave with special plumbing tasks and electrical upgrades for process improvements throughout our company. National HVAC always shows up on time in a professional manner and accomplishes all tasks. In a world that is changing every day, National HVAC Service is my go-to for HVAC, plumbing, and electrical solutions. From one group of professionals to another Thank you National HVAC.
In my over 30 years at WMDT, National HVAC Service has been a trusted resource and have completed many projects with us. These projects have included all their trades such as Electrical, HVAC, and Plumbing. They were instrumental in our FCC channel repack, and have always been available and quickly responded to all our emergencies as well.
Awesome service focused company. Everyone we have dealt with is polite and very knowledgeable in the services they have provided our company over many, many years. I would recommend National HVAC Service to anyone. Great people! Great partners!
Furnace out? AC quit?
Commercial system down? We answer around the clock.
60+ years, 40+ technicians, eight trades — one call gets the right crew to your Delmarva home or facility. Talk to our team now or request service online.