You want to do some research before buying a new heating, ventilation and air conditioning system.

While you’re Sherlock Holmes sleuthing around the  internet for price and reliability you can recruit a trusty aide Watson in the form of an HVAC installer.

Indeed, the HVAC contractor should be a top priority on your checklist. Interview three contractors; that sounds like a lot of legwork but you will be paying a lot of money for a new HVAC.

• One key area: Is the size of the new system correct for your home and can the contractor install it correctly. A surprising number of installations are done incorrectly, meaning problems immediately and/or down the line.

• Ask contractors which systems they prefer; don’t hire a company that installs only one brand.

• Also, ask them which are their least favorite HVAC brands. They all have a nominee or two, and they can cite experiences to support their opinions.

Budget-busters

The high-end systems tend to be more reliable, more durable and quieter, but maybe they cost more than you’re willing or able to pay.

Mid-range brands will get the job done for less money up-front, although they may need repairs sooner and not last as long as more expensive systems.

Much factual information is easily available on-line, such as Seasonal Energy Efficiency Ratio (SEER) and certification by Energy Star, a government label which outlines energy efficiency.

If possible, get a variable-speed model. It will be more efficient, quieter and provide more humidity control than a single-speed version.

A smart thermostat also is valuable. It gives you more efficiency and remote control of your thermostat.

Red flags

Beware of companies that offer only short warranties. This means they are unsure of their system’s quality and durability.

A high-quality company will warranty their system for 10 years or more. That’s a good length of coverage for compressors, heat exchangers and other expensive components.

Need HVAC help in NYC? Premier HVAC is based in Brooklyn and is available 24/7.