Heating Installation in Commack, NY

We have installed gas furnaces at three Commack homes. Two in May 2015 each received an 80% Rheem furnace rated 75,000 BTU with 3.5 tons of cooling. The October 2022 job replaced an older furnace with a 95% Rheem furnace rated 100,000 BTU, new PVC venting and two in-duct air purifiers.

• May 2015 (two homes, one week apart): a complete forced-air package in each house, pairing the 80% furnace with a 3.5-ton cooling system on the same blower and ducts.
• October 2022: the existing furnace was removed, the 95% furnace was set in its place, the old flue pipe was replaced with PVC venting, and two iWave purifiers were mounted in the ductwork serving heat and cooling.
• November 2022: at the same home, up to five worn flex supply runs across both floors were replaced with new 7-inch airtight takeoffs and 7-inch flex, then the system was balanced.

The percentage is the share of the gas's heat that reaches your home. An 80% furnace sends hot exhaust up a metal flue or chimney. A 95% furnace pulls extra heat from the exhaust with a second heat exchanger, leaving it cool enough to vent through PVC pipe, and it produces condensate that needs a drain.

That is why the October 2022 Commack job included new venting: the old flue pipe could not serve a condensing furnace, so it was replaced with PVC. The 2015 installs used 80% furnaces, which could keep a conventional flue. A condensing furnace uses less gas for the same heat, but it only makes sense where the PVC vent and the condensate drain have a sensible path out of the house.

A new furnace moves air only as well as the ducts let it. After the October 2022 Commack install, we went back in November and replaced up to five flex supply runs on the first and second floors with 7-inch airtight takeoffs and new flex, then balanced the airflow.

Flex duct that sags, kinks or pulls loose at the takeoff starves the rooms at the end of the run, and a stronger furnace can't fix that. Tying both ends tightly, sealing the joints and supporting the runs so they stay straight restores the air those rooms were missing. If some rooms in your Commack home never warm up, the ducts are worth checking before or alongside a furnace replacement.

Often, yes. In a forced-air home the furnace blower moves the air for both heating and cooling, and the AC coil sits on the furnace cabinet. Both May 2015 Commack installs replaced the furnace and cooling together, so the coil fit the new cabinet and the blower was matched to the cooling load.

Replacing just the furnace is reasonable when the cooling equipment still has good years left; in the October 2022 job only the furnace was replaced and the existing cooling stayed. When the cooling equipment is near the end of its life, doing both at once avoids a second round of work on the same closet a few years later. For cooling-only replacements in the hamlet, see our Commack AC installation page.

Ignition parts, control boards, inducer motors and blower capacitors are the common failures. In December 2025, a Commack no-heat call traced to a failed furnace control board; we replaced it along with the hot surface igniter and cleaned the coil, and on a return visit replaced the blower capacitor and adjusted the gas pressure.

That job is written up as our Commack no-heat control board repair. A single repair like that is usually worth doing on a furnace that is otherwise sound. The case for replacement builds when repairs repeat, parts get hard to find, the heat exchanger shows cracks or rust, or rooms stay uneven no matter what is fixed. Our Commack draft inducer motor repair shows another common furnace fix in the hamlet, and our Commack furnace repair page covers no-heat calls.

Commack straddles two towns. West of Townline Road you are in the Town of Huntington, served by the Department of Engineering Services; east of it you are in the Town of Smithtown, served by its Building Department. K2 does not file permits, so check with your town's office before work begins.

Gas furnace work also involves the gas service and venting, so mention any planned fuel change when you call that office. Your tax bill names the town your house belongs to. We can provide model numbers and input ratings once the quote is settled.

Each Commack heating install is quoted in writing after a visit. The figure depends on furnace size and efficiency, the venting a condensing unit needs, whether cooling is replaced at the same time, duct repairs and any add-ons such as air purifiers. Our furnace and boiler replacement cost guide walks through those factors.

Financing is offered through Rheem KwikComfort, with credit provided by Synchrony Bank, subject to credit approval. After start-up we help register the furnace with the manufacturer; see our warranty page. Read more on heating installation and the Commack HVAC hub, or see our heating work in nearby Dix Hills and Smithtown.