Another issue is that the Microsoft operating systems, particularly Windows 10 and Windows 8, cause some features to not work like they did on earlier operating systems. While we can make our programs backward compatible, no one can make them forward compatible, but we try to keep up.

Our current versions are HVAC-Calc Residential 4.0.70 and HVAC-Calc Commercial 4.0.70. To check your programs version number, simply look at the upper left of the title bar when the program is running. Version 4.0.70 (and newer) runs great on Windows 10 and on Windows 8 as well as earlier operating systems.

If you have an older version or you have lost your registration number, you should click here to order a $79 update. After we charge your card, you will get an email with a link to download an update and receipt by email.

Anyone purchasing the program or an update within the last 12 months is eligible for a free update. Please contact us by email, don@hvaccomputer.com ( don@hvaccomputer.com ) and we will send you the information you need to get a free update.

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