DJG Insulation installs and replaces residential heating and cooling systems across Central New Jersey: air-source heat pumps, gas furnaces, central air conditioning and ductless mini-splits. We are the same crew that has been air sealing attics and encapsulating crawl spaces in these towns since 2019. That changes one thing in particular. We size your equipment against how your house actually performs, not against its square footage. Free estimates, permitted work, and a licensed New Jersey Master HVACR contractor in NJ on every job.
What we install and replace
Our HVAC work splits into four jobs: replacing equipment that has reached the end of its life, adding heating or cooling to a space that never had it, building the mechanical package on new construction, and correcting the ductwork that everything else depends on.
Equipment we install:
- Air-source heat pumps, ducted central systems and ductless mini-splits
- Gas furnaces
- Central air conditioning systems
- Smart thermostats and zoning controls
Ductwork and distribution:
- New duct design for additions and full replacements
- Duct sealing at seams, boots and plenums
- Duct insulation in attics, crawl spaces and garages
- Register and return sizing where rooms run hot or cold
Ductless mini-splits go into the spaces the original system was never designed to reach. Finished basements. Sunrooms. Garages converted to offices. Bonus rooms over an unheated garage, which in this part of New Jersey is one of the most common comfort complaints we hear.
Why your insulation decides the size of your furnace
A load calculation reads your insulation, your air leakage and your window area, then returns a number in BTUs. Change the insulation and the number changes with it. That is the whole argument, and it is the reason we do this work in the order we do.
Most replacement quotes in this market are sized off the old equipment. The installer reads the data plate on your 22-year-old furnace, sees 100,000 BTU, and quotes you 100,000 BTU. Nobody asks whether the original was correctly sized in 1998, and nobody asks what has changed in the attic since. An ACCA Manual J calculation asks both.
Here is what oversizing costs you. A furnace with more capacity than the house needs satisfies the thermostat quickly and shuts off, then fires again a short while later. Short cycling wears the ignition components, swings the temperature between rooms, and on the cooling side leaves the air conditioner no run time to pull humidity out, which is why an oversized system can leave a house cold and clammy at the same time.
Sealing the attic and bringing the insulation up first lowers the calculated load. A lower load means smaller equipment, and smaller equipment costs less to buy, less to run, and less to replace in fifteen years. We can quote the envelope work and the mechanical work in the same visit because both crews are ours.
Ducts matter for the same reason. When supply ducts run through an unconditioned attic, every unsealed seam and every uninsulated run bleeds conditioned air into a space nobody lives in. Sealing and insulating that ductwork is attic insulation work as much as it is HVAC work, and we do not treat it as somebody else’s scope.
How a system replacement runs
A replacement moves through five stages, and you will know which one you are in at every point.
- Estimate visit. We look at the existing equipment, the ductwork, the attic and the crawl space, and we take the measurements the load calculation needs.
- Load calculation and proposal. You get the sizing, the equipment options, and where the envelope work would change the answer.
- Permits. Mechanical and electrical permits are filed with your municipal construction office before anything is removed. Work done without a permit can hold up a future home sale.
- Installation. Old equipment out, new equipment in, ductwork corrected where the proposal called for it, jobsite cleaned before the crew leaves.
- Inspection. The municipal inspector signs off. We register the equipment with the manufacturer so the warranty stands.
Clean jobsites are not a slogan here. Our insulation customers already know what our crews leave behind, which is nothing.
New construction and additions
Builders and general contractors get the thermal and mechanical package from one subcontractor. Insulation, air sealing, ductwork and equipment, scheduled by one company against one set of dates.
The practical benefit shows up in the sequencing. Rough-in, insulation inspection and mechanical trim usually involve three phone calls and three sets of availability. With DJG it involves one. When the air sealing crew finds a problem behind the mechanical chase, the mechanical crew is already ours. For projects where an energy model was submitted, the building performs closer to what the model predicted, because the same team that installed the envelope installed the equipment sized against it.
We work with builders across Monmouth, Ocean and Middlesex counties on single-family, multifamily and light commercial projects.
What money is actually available in 2026
The federal tax credits are gone. The New Jersey rebates are not.
This is worth getting right, because a lot of contractor websites in this state have not updated. Sections 25C and 25D, the federal Energy Efficient Home Improvement Credit and the Residential Clean Energy Credit, both terminated for property placed in service after 31 December 2025 under Public Law 119-21. Anything installed in 2026 earns zero federal credit. If a contractor quotes you a job and tells you to take $2,000 back on your taxes, ask them when they last checked.
What remains live in New Jersey:
- Utility equipment rebates on qualifying heat pumps, ductless systems and central air conditioning, paid through the New Jersey Clean Energy Program and administered by your electric and gas utility. Amounts step up with efficiency rating. JCP&L publishes its current tiers here.
- The Whole Home Energy Efficiency Program, worth up to $7,500 depending on the modeled energy savings your project delivers. Deeper savings pay more, which is exactly where a combined envelope and equipment project scores better than equipment alone.
- Zero interest financing through the state program on qualifying projects.
The Whole Home path starts with a whole-home energy assessment, not with equipment shopping. Homeowners who buy the system first frequently disqualify themselves.
Where we work
We cover Monmouth, Ocean and Middlesex counties from our shop at in Wall Township.
Our insulation crews have been running these roads since 2019, and the HVAC division works the same footprint. If you are outside the three counties and the project is large enough to justify the drive, call and ask.
Questions homeowners ask before they book
Next step
Contact Us Today for a FREE Estimate. Tell us what the house is doing wrong, and we will come look at the equipment and the attic on the same visit.