OMS INC, also known as Onken Mechanical Service, is a reputable HVAC contractor serving areas in the south metro Denver region, including Parker, Castle Rock, Highlands Ranch, Aurora, and Centennial. We offer a range of services, including installation, repair, and maintenance of heating and cooling systems for both residential and commercial properties. With a strong reputation for excellence in both heating and air conditioning services, OMS INC is highly regarded as a top choice for HVAC needs in Colorado
For Service Call 720-670-0459

Fast Professional Air Conditioning and Heating Service


OMS INC is here to help you with all of your heating & air conditioning needs and Heating, Furnace, Boiler and Air conditioning repair. With 29 years of experience to help you to address all of your home comfort needs more accurately than many other HVAC companies. Onken Mechanical Service Parker  Castle Rock.  Fast Professional Heating air conditioner repair and replacement. ​​​​NATE Certified Heating and Air Conditioning techs, License and Insured, locally owned were here for your comfort.

Our Team

OMS Inc. Heating and Air Conditioning has been in the business for over 15 years and with 29 years in the industry have paid enough attention to learn a thing or two over those years. We've even worked hard to make sure that our NATE Certified techs know the most up to date information about all of your heating and cooling needs. Keeping your home Comfortable and Safe is our goal! 5 Star Rated Furnace - air conditioner repair in Parker, Castle Rock and surrounding areas. Call today for all your HVAC needs


Heating Repair, Service, Sales, Installation, Design and replacement of gas heating appliances such as Furnaces, Boilers , Water heaters and Air conditioning. ​We have worked with everything that's out there so rest assured that we have the knowledge to service even the toughest HVAC issues and repairs. We've also got a skilled set of workers who are knowledgeable about any type of HVAC system you have. With you and your loved ones in mind, we've started offering different products to help with your home's air quality.​

We also can assist with forensic fire investigations to confirm or rule out the involvement of HVAC equipment in a loss claim. Your source for heating and air conditioning.

Our FLIR tech can find pipes behind walls and diagnose issues with air flow as well as insulation properties of your home.

We have Drone ariel tools for assessment of flues and rooftop equipment.


HVAC is our only business.

Our Goal is to be the company you will recommend to family and friends. OMS Inc services Parker, Elizabeth, Castle Rock, Highlands Ranch, Lone Tree, Castle Pines, Centennial, SE Aurora, Franktown and surrounding areas. We serve the south metro area and surrounding communities.

Need maintenance or new equipment? You can feel comfortable with our 29 years of experience in the industry and our dedication to keeping your home comfortable healthy and safe.

We are licensed, insured and NATE certified and have a great team of skilled techs to repair or replace your heat or air conditioner. We also work on light refrigeration equipment and chillers.

Professional HVAC Repair and Sales

Free Estimates on New Equipment

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Whats the word on Oms Inc.? Here is what some of our customers are saying

“I can't say enough good about Glen! He showed up on time, correctly diagnosed the problem and resolved it right away. I had already dealt with another AC technician who ripped me off and never figured out why my AC didn't work. Glen was very conscientious, answered all my questions, made sure I understood what the problem was, what my repair options were, and fixed the system. After almost 2 weeks without AC, it was wonderful to wake up in a 70 degree house instead of a 79 degree house! He cleaned up everything he touched and left the house like he found it. He called the next day to make sure we were happy. I wouldn't hesitate to recommend his services to anyone."

Mark K.

Onken Mechanical Service 6/20/2017

“This job was to service and certify the furnace and service the AC. He and his assistant were considerate and easy to talk to. Took their shoes off at the door and cleaned up after themselves."

Review by a homeowner in Aurora, CO

Project: Repair or Service a Central Air Conditioning System

I can’t say enough about Glen and his staff. 100% amazing. If you were to write down what your perfect contractor experience would look like, with 100% confidence it will be what you will experience with glen and his team. Their customer service is over the top. Prices are awesome and unbeatable!!

Joseph Sabia

OMS INC. July 2019

Professionalism, Punctuality, Quality, Responsiveness, Value
What a great group of people to deal with!
Glen was friendly, knowledgeable and informative. He spelled everything out for us and gave us all our options.
The install guys were really hard workers. They finished the job in one day and kept me posted on what was happening throughout the day.
Right now it's 90 degrees outside and I'm cool and comfortable in my home.
I would highly recommend Glen and OMS for any air conditioner or heater jobs.

Marc F


Very satisfied. Been using for my residence, as well as heating and air needs at 10 rental properties. Glenn is very cost conscious, and most importantly, TRUSTWORTHY. You will NOT be disappointed.

Rosemary W