What Size AC Do I Need for My NYC Apartment?
Proper AC sizing depends on room dimensions, window orientation, ceiling height, and insulation — not just square footage. We calculate this for every air conditioning installation.
How do you calculate the right BTU for my apartment?
We start with your room’s square footage — a 400 sq ft studio needs about 8,000 BTU, while a 700 sq ft one-bedroom needs 12,000 BTU — then adjust for ceiling height, window orientation, and insulation. A pre-war apartment with 10-foot ceilings pulls a 25% BTU bump right off the bat. South-facing rooms with floor-to-ceiling windows need 20% more BTUs than north-facing rooms of the same size — a mistake I see homeowners make every summer.
What factors affect AC sizing beyond square footage?
- Ceiling height: Pre-war apartments with 10–12 ft ceilings need 25–30% more BTUs than a standard 8-ft build.
- Window orientation: South- and west-facing rooms get 20% more solar load; north-facing rooms can subtract 10%.
- Insulation quality: Single-pane windows and uninsulated walls in older buildings add 20% to the requirement.
- Occupants and appliances: Each person beyond two adds 600 BTU; a kitchen with an oven adds roughly 4,000 BTU.
- Real-world example: A 500 sq ft pre-war apartment with 10 ft ceilings and south-facing windows needs 14,000 BTU — not the 8,000 BTU most people buy from big box stores.
Do you use Manual J calculations for central AC and mini-splits?
Yes — we use Manual J load calculation software for all central AC and mini-split installations, measuring insulation values, window U-factors, air leakage, and duct losses. In the field, I’ve seen a 500 sq ft studio come out at 12,000 BTU after Manual J, not the 8,000 a rule-of-thumb would suggest. Manual J is the industry standard that prevents the two most common NYC sizing mistakes — undersized units that run 24/7 and oversized units that short-cycle and fail to dehumidify.
Do I Need a Permit for AC Installation in NYC?
NYC has specific permit rules for AC installation based on system size and type. We handle all permitting so you don’t have to worry about fines or legal issues.
When does a window AC need a DOB permit in NYC?
Standard window AC units under 36,000 BTU/hr (3 tons) do not require a DOB permit — this covers 99% of residential window AC installations in NYC. The threshold comes directly from nyc.gov, which states that a work permit is generally not needed for common window units below that capacity. In the field, I see homeowners assume every installation needs city paperwork, but for a typical 8,000–14,000 BTU window unit in a studio or one-bedroom, you’re clear on the DOB side. Still, the AC installation NYC permit question isn’t just about DOB — Local Law 39 requires safety brackets for any window AC above ground floor, and we install these on every window unit to keep you compliant.
What AC installations require a DOB permit?
| AC Type | DOB Permit Needed? | Typical BTU Range | Electrical Permit Needed? |
|---|---|---|---|
| Window AC | No (under 36k BTU) | 5,000–14,000 | No (plug-in) |
| Through-the-wall AC | No (under 36k BTU) | 8,000–15,000 | Yes (new circuit) |
| Mini-split (single zone) | No (under 36k BTU) | 9,000–12,000 | Yes (dedicated circuit) |
| Mini-split (multi-zone) | Yes (over 36k BTU) | 24,000–48,000 | Yes |
| Central AC | Yes | 36,000–60,000 | Yes |
| PTAC (single unit) | No (under 36k BTU) | 7,000–15,000 | Yes (dedicated circuit) |
Can You Install a Mini-Split in a Brooklyn Brownstone?
Brooklyn brownstones present unique challenges for mini-split installation — plaster and lathe walls, roof access, and historic interiors. We’ve done dozens of these installations.
How do you route line-sets in a brownstone with plaster and lathe walls?
We run line-sets through closets or use exterior line-set covers on the rear facade — fishing through plaster and lathe walls damages the historic interior and takes twice as long. For a typical 3-story Brooklyn brownstone, the cleanest route is through the basement ceiling joists, then up through interior closets on each floor, keeping the original pre-war plaster intact. The line-set cover, a paintable PVC channel, mounts flush against the brick facade and hides the 1/4-inch liquid line and 3/8-inch suction line. A mini-split installation Brooklyn job on a brownstone with this approach takes about 5-6 hours for a single zone versus 8+ hours if we had to cut and patch plaster. For multi-story brownstones, we often route line-sets through the basement ceiling and up through interior closets, keeping the historic plaster walls intact.
Where do you place the outdoor condenser on a brownstone?
- Flat roof placement: The ideal spot — keeps the condenser unit out of sight from the street and away from neighbors’ windows, which helps avoid NYC Noise Code complaints after 10 PM.
- Rear facade wall bracket: Works when roof access is blocked or the roof is shared with a co-op. We use vibration-dampening pads and keep the unit at least 10 feet from neighboring windows.
- Concrete pad on the roof: Preferred over brackets for heavy multi-zone condensers (3-zone units weigh 130-180 lbs). We bolt the pad to the roof deck with stainless steel anchors.
- What we avoid: Front facades (historic district restrictions) and fire escapes (blocked egress). Brownstone rear yards work only if the unit is at ground level with a 3-foot clearance for airflow.
Can you install a multi-zone mini-split for a 3-story brownstone?
Yes — a 3-zone mini-split with one outdoor unit serving three indoor heads (one per floor) is the most common setup for a 3-story brownstone, typically 24,000-36,000 BTU total. A 3-zone Mitsubishi Electric system with Hyper-Heat technology handles Brooklyn’s winter heating down to -13°F, making it a year-round solution. The indoor heads mount high on interior walls — one in the parlor floor living room, one on the second-floor master, one on the third-floor bedroom — all connected through a single line-set bundle running up the rear facade. We check your electrical panel first — brownstones often have 100A panels, and a 3-zone mini-split may require a panel upgrade to 200A.
Can You Install a Through-the-Wall AC in a Pre-War Building?
Pre-war buildings have thick masonry walls with embedded wall sleeves. Installing a through-the-wall AC requires measuring the sleeve, checking its condition, and matching the right unit.
What wall sleeve sizes do pre-war NYC buildings use?
| Sleeve Size | Typical Building Era | Common AC Brands | Notes |
|---|---|---|---|
| 26″ × 16″ | 1920s–1940s | Friedrich, GE | Most common size |
| 28″ × 17″ | 1930s–1950s | Friedrich, LG | Larger units |
| 24″ × 14″ | 1910s–1930s | Friedrich, Amana | Older buildings |
| Non-standard | Pre-1910 | Custom fit | Requires adapter kit |
What if the wall sleeve is rusted or damaged?
If the sleeve is rusted through or structurally compromised, we replace it — this involves cutting into the brick, installing a new sleeve, and repointing the masonry. A rotted sleeve won’t support the unit evenly, which throws off the pitch for condensate drainage and lets outside air leak around the chassis. Sleeve replacement takes 4-6 hours and requires a masonry specialist — we coordinate this as part of the through-the-wall AC installation NYC so you don’t need a separate contractor.
Do you need building management approval for through-the-wall installation?
- Co-op board approval: Most co-ops require a formal alteration application before any wall penetration — some ban through-the-wall units entirely and only allow window AC or mini-splits.
- Condo restrictions: Condo boards typically require proof of insurance, a licensed installer, and a signed alteration agreement; approval can take 1-3 weeks.
- Rental buildings: Landlords often restrict through-the-wall installations because the sleeve becomes a permanent building modification — get written permission before ordering the unit.
- No-board buildings: Single-family pre-war rowhouses and some two-family brownstones don’t need board approval — but you still need to check the sleeve condition and measure the opening.
Do You Install PTAC Units for Hotels or Co-ops?
PTAC units are common in NYC hotels and co-op buildings. We install LG, Friedrich, and GE PTACs — from single-unit replacements to bulk hotel installations.
What PTAC brands do you install?
- LG: Popular in mid-range hotels and newer co-op buildings; inverter models run quieter and use less power than traditional units.
- Friedrich: The most common brand across NYC hotels and co-ops — their standard 42″ × 16″ sleeve fits most wall openings without an adapter kit.
- GE: Budget-friendly option for smaller hotels or co-op apartments; parts are widely available through local NYC suppliers.
- Amana: Solid choice for extended-stay hotels where durability matters; 1-year warranty on parts and labor from our end covers the install.
- Carrier: Premium tier for boutique hotels; their PTACs have higher SEER ratings and better condensate management than entry-level models.
For co-op buildings, we recommend Friedrich PTACs because their standard 42″ × 16″ sleeve fits most NYC wall openings without adapter kits.
How long does a PTAC replacement take?
A single PTAC replacement takes 1-2 hours — for bulk hotel installations, a 2-person crew can replace 10 units per day. The process breaks down: disconnect power and condensate drain (20 minutes), inspect and clean the sleeve (20 minutes), slide in the new unit and secure it (20 minutes), then test all modes — cool, heat, fan speeds. In our practice, the sleeve condition is the variable that eats time; rusted or out-of-level sleeves need shimming or replacement before the unit goes in. We check condensate drainage on every PTAC installation — if the sleeve isn’t sloped 1/4″ per foot, water pools inside the unit and causes mold within weeks.
What electrical work is needed for PTAC installation?
PTACs require a dedicated 208/230V circuit with a 20A breaker — older buildings may need a panel upgrade or new sub-panel for multiple units. A co-op in a pre-war building with a 60A panel can’t run more than two PTACs without upgrading to at least 100A service. That panel swap runs $4,500 to $6,500 depending on riser access and whether the meter needs relocating. We handle all electrical work in-house with NY Master Electrician licensed techs, so you don’t need a separate electrician for PTAC installation.
Conclusion
These are the main points to hold onto when planning your AC installation in NYC—from sizing to building-specific logistics.
Main takeaways
Getting the right AC installation in NYC starts with proper sizing—measure your space, check your window orientation, and consider your building’s construction. Permits depend on system size: window units under 36,000 BTU don’t need DOB approval, but central AC and multi-zone mini-splits do. Brooklyn brownstones are ideal for mini-splits with careful line-set routing through closets or exterior covers. Pre-war buildings need sleeve measurements before ordering through-the-wall units. For hotels and co-ops, PTAC replacements are straightforward but require proper condensate drainage and electrical work. We’ve covered the key questions homeowners ask when planning an AC installation—from sizing calculations to building-specific considerations.
