Frequently asked questions

Every neighborhood in Brooklyn, Queens, Staten Island and Manhattan. We do not currently serve the Bronx.

Yes. A dispatcher answers 646-980-2411 24 hours a day, 7 days a week, including holidays.

Yes. Work is performed under a NYC licensed master plumber, and the company is insured. Licence numbers are listed in the footer of every page.

Yes. You get a written estimate after diagnosis, and work starts only after you approve it.

Yes. Both are Class C, immediately hazardous violations. Heat is required October 1 to May 31 and hot water at 120°F all year, and owners must restore service within 24 hours.

We dispatch 24/7 across Brooklyn, Queens, Staten Island and Manhattan, and most calls get a plumber on site in about an hour. The dispatcher gives you an arrival window when you call.

Both. We repair one-pipe and two-pipe steam systems common in pre-war buildings, and forced hot water systems with circulators and zone valves.

Common causes are a dirty flame sensor or thermocouple, a failing ignitor, poor venting, low gas pressure, or a low-water cutoff tripping on a steam boiler. The fix depends on which one, so it needs a diagnosis rather than repeated resets.

It means water is leaving the closed system somewhere: a leak in the piping, a relief valve discharging, or a failed expansion tank pushing water out. It should be found and fixed before the boiler runs short of water.

Yes. You get a written estimate after diagnosis, and work starts only after you approve it.

Usually when the boiler is 15 to 20 years old or more, has needed several repairs in one season, has a cracked heat exchanger or section, or the repair would cost a large share of a new boiler.

Most one- and two-family homes are done in one working day. Larger apartment-building boilers usually take two to four days, depending on the size, piping and venting work.

Yes. Private houses are a large share of our replacements, especially in Queens, Staten Island and southern Brooklyn. We size the boiler for the house, not just the old unit.

Yes. We coordinate with supers and managing agents, plan around tenants, and provide the insurance certificates buildings ask for.

Yes. A conversion usually means a new gas boiler, a new or upgraded gas line and meter coordination with the utility, removal or abandonment of the oil tank, and a chimney liner or new venting.

Yes. Boiler and gas work in NYC must be done under a licensed master plumber with the required Department of Buildings filing. We handle the paperwork.

Often, for hot water systems in houses. They need PVC venting and a condensate drain, so the building has to allow for that. Steam systems need a steam boiler, not a condensing hot water unit.

Usually, yes. We carry 40, 50 and 75 gallon tanks on the truck, so a standard replacement is typically finished in 2 to 3 hours after we arrive.

40 gallons suits 1 to 2 people, 50 gallons suits 2 to 4 people and is the most common replacement, and 75 gallons suits larger households, multiple bathrooms or light commercial use.

Yes. Going from 40 to 50 or from 50 to 75 gallons is common. We confirm the space, venting and gas supply can handle the larger unit first.

Yes. Gas water heater replacement must be done by a licensed master plumber with the required Department of Buildings filing. We take care of it.

Yes. Removal and disposal of the old water heater is part of every replacement.

Yes. Hot water is required all year at 120°F or higher at the tap. Lack of hot water is a Class C, immediately hazardous violation that must be corrected within 24 hours.

Water expands when it heats. In a closed system there is nowhere for that extra volume to go, so pressure rises. The expansion tank holds an air cushion behind a rubber bladder that absorbs the extra water and keeps pressure steady.

Where the water supply is a closed system, for example because of a check valve, backflow preventer or pressure-reducing valve, the plumbing code requires thermal expansion control, which is normally an expansion tank. Hot water heating boilers also need their own expansion tank.

Common signs are a water heater relief valve that drips, boiler pressure that climbs when the boiler runs, and banging pipes. A plumber can confirm by checking the tank: a failed bladder lets water out of the air valve.

No. The water heater needs a tank rated for drinking water. The boiler uses a hydronic tank on the heating loop. They are not interchangeable.

Usually under an hour, including setting the air pre-charge to match your water pressure.

Stop using water everywhere in the building, keep people and pets away from the water, do not pour chemical drain cleaners in, and take photos for insurance. Then call.

In NYC, the property owner is generally responsible for the house sewer line, from the building out to the connection at the city sewer in the street. The city is responsible for the main.

A U-shaped fitting on the main drain, usually in the basement or front of the building, found in many older NYC buildings. It is one of the most common places for a blockage.

Many homeowner policies exclude sewer backup unless you have a separate rider. Check your policy. We document the cause and damage for any claim.

With a camera inspection of the line after it is cleared. It shows roots, grease, sagging pipe or a collapse, and we show you the footage.

Yes. Dripping faucets, running toilets, clogged sinks and tubs, leaking shutoff valves and noisy pipes are everyday work for us in Brooklyn, Queens, Staten Island and Manhattan.

A faucet dripping once a second wastes thousands of gallons a year. In a multi-unit building, a few dripping faucets and running toilets add up on the water bill quickly.

We recommend against it, especially on older cast-iron and galvanized pipes common in NYC. It can damage the pipe and makes the job hazardous for the plumber. A plunger or plastic drain snake is safer for a first try.

Yes. A plumbing check covers fixtures, shutoff valves, visible supply and drain piping, the water heater and signs of leaks, with a written list of what needs attention.

Yes. We follow building work hours and provide certificates of insurance when the managing agent requires them.

Usually, yes. The main questions are gas supply and venting. A gas tankless heater burns much more gas at full output than a tank, so the gas line and sometimes the meter need upgrading, and it needs its own vent. We check both before quoting.

Tankless gives continuous hot water, saves space and wastes less energy keeping water hot. It costs more to install and needs yearly descaling. For large households that run out of hot water, or tight spaces, it is often worth it. For a simple same-day replacement, a tank is faster and cheaper.

Yes. They should be descaled, usually once a year, because mineral build-up inside the heat exchanger cuts output and triggers error codes. We also clean the inlet filter and check venting and combustion.

Common causes are scale build-up, a flow rate too low to keep the burner lit, a clogged inlet filter, a gas supply too small for the unit, or a venting or ignition fault shown as an error code.

Yes. Gas water heater installation must be done by a licensed master plumber with the required Department of Buildings filing, and gas line changes are part of that work. We handle the paperwork.

Yes, including error codes, ignition and flame faults, scale problems, leaks and venting issues on major brands such as Navien, Rinnai, Noritz and Rheem.

In most cases, yes. A permanent ductless mini split is mechanical and electrical work. It generally needs Department of Buildings approval, usually filed by a licensed engineer or architect, plus an electrical permit filed by a NYC licensed electrician. Get the permits in place before installation starts.

Unpermitted work can lead to DOB violations and fines, stop-work orders, problems when you sell or refinance, insurance complications, and a requirement to legalize or remove the system later.

Yes, almost always. Expect an alteration agreement, drawings, equipment specifications and insurance certificates. Some boards restrict where outdoor units and line sets can go. Start the board process early.

Often, yes, but if the outdoor unit or line set is visible from the street, the Landmarks Preservation Commission must approve it before the DOB permit is issued.

Yes. Mini splits are heat pumps. Cold-climate models can heat efficiently in NYC winters, and many owners use them to supplement or reduce reliance on the boiler.

Sometimes. A licensed electrician checks your panel and service capacity before installation. Multi-zone systems in older homes are the most likely to need more capacity.

As often as needed to keep it below its rated capacity, which is what NYC DEP rules require. For most busy kitchens that means weekly to monthly. We set the schedule from what we find at the first few visits, then adjust it.

No. NYC DEP does not allow food waste disposers in commercial establishments. If one is installed, it should be removed.

Yes. Under NYC rules, commercial dishwasher discharge and floor drains that can receive grease must flow through the grease interceptor. Water entering the interceptor should not exceed 180°F.

Only a licensed plumber, under NYC DEP rules. We size it to your kitchen and install it to code.

Yes. Scheduled maintenance is done outside service hours so the kitchen never has to shut down for it. Emergencies are handled any time.

A dated service report after every visit: what was cleaned, the condition of the interceptor and lines, and anything that needs attention. Keep these on site for DEP and health inspectors.

Yes. Backflow prevention devices must be tested every year in NYC, and the test results filed with DEP. We schedule the test and handle the filing.

Yes. GW Mechanical Corp offers one-time maintenance visits and annual maintenance plans for homes, apartment buildings and restaurants in Brooklyn, Queens, Staten Island and Manhattan. A visit covers the water heater, boiler, expansion tank, fixtures, drains and shutoff valves, with a written report and photos. Plan members get a scheduled fall visit and priority dispatch in winter.

Yes, measurably. A boiler that is cleaned and combustion-tested every year commonly reaches 20 to 25 years; one that is never serviced often fails at 12 to 15. A tank water heater that is flushed yearly and has its anode rod checked reaches its 10 to 12 year design life instead of failing at 6 or 7. An expansion tank is checked for correct air charge each visit and replaced when waterlogged, which protects the boiler, the water heater and the relief valve from pressure damage. Clearing scale and sediment also keeps water flow and pressure where they should be.

Have the boiler serviced before October 1: burners cleaned, combustion tested, safety controls tested, expansion tank and system pressure checked, and on steam boilers the low-water cutoff flushed and vents checked. Replace thermostat and carbon monoxide alarm batteries. Flush the water heater and test its relief valve. Bleed radiators, insulate pipes in unheated spaces, shut off and drain outdoor spigots, and clear the vent terminations outside. Our winter heating maintenance checklist walks through every step.