Our Story
Built on Honesty.
Driven by Community.
From a one-man operation in Berthoud to a trusted Northern Colorado HVAC team — we've never lost sight of what matters: honest work for our neighbors.
Since 2014
A Family Tradition of Quality
A Plus was established in 2014 by Darren Knoll of Berthoud, CO. With decades of experience in the HVAC industry, Darren aimed to provide Northern Colorado with honest and reliable heating and air conditioning services.
In 2022, as Darren approached retirement, he reached out to his cousin Zach Karre, who had been in the HVAC industry for 8 years. Zach gained a love for the trade at age 16 and attended trade school at Mid Plains Community College, graduating as head of his class.
In March 2023, Zach took ownership and brought fresh energy while maintaining A Plus's core commitment to honest, reliable service and an unmatched customer experience.
Our Journey
Key Milestones
A Plus Heating & A/C founded by Darren Knoll in Berthoud, CO
Darren reaches out to cousin Zach Karre about succession planning
Zach takes ownership, bringing fresh energy and continued commitment to honest service
Grant begins apprenticeship through Roosevelt High School partnership
Zach named one of NOCO Style's 30 Under 30 honorees
A Plus surpasses 200 five-star Google reviews
Meet the Team
The People Behind Your Comfort
Zach Karre
Owner
Zach gained a love for the HVAC trade at age 16. He graduated head of his class at Mid Plains Community College, took ownership of A Plus in March 2023, and was named one of NOCO Style's 30 Under 30 in 2025.
Kelsey
Office Manager
Kelsey keeps operations running smoothly, ensuring every customer receives prompt, friendly service from their first call.
Jacob
Technician
Jacob brings technical expertise and dedication to every job, ensuring quality workmanship on installations and repairs.
Grant
Service Technician
Grant started as an apprentice at age 16 through Roosevelt High School's work-based learning program. After graduating, he became a full-time service technician with A Plus.
Community First
More Than Just HVAC
We believe in investing in the communities we serve. A Plus partners with Roosevelt High School to provide apprenticeship opportunities for young people entering the trades, and we participate in Lennox's Feel The Love program to provide free HVAC systems to families in need.
RHS
Apprenticeship Program with Roosevelt High School
Feel The Love
Lennox program providing free systems to families in need
Ready to Experience the A Plus Difference?
Join over 200 homeowners who trust us with their comfort.