Can an HVAC installer's warranty be voided if another company works on the system?

Question

After moving into a new home, I had a licensed HVAC company install a whole house humidifier. A few days later, a guy from the builder's HVAC contractor came out to address an airflow issue. When he saw the humidifier, he told me that because I let another company work on the system, my warranty is now void.

He told me I should have known that because the warranty terms are spelled out in a binder full of paperwork the home builder gave me. After searching through the binder, I finally did find that clause, but I wouldn't call it obvious information. I don't remember signing anything saying I agree to the conditions. The papers were simply handed to me when I bought the house.

To be clear, the manufacturer's warranty still applies. It's only the installer's warranty on their workmanship that's considered void.

Is voiding a warranty like that legal? Would the Magnuson Moss Act protect me? I'm in Idaho, USA.

Answer 1

You can read about Magnuson Moss here, but it only applies to warranties on goods, not services. As you note, the warranty on the unit is still valid.

As for agreeing, it is not unusual that a consumer is not aware what all they are agreeing to when they buy a house. One of those myriad signatures that you put on myriad documents was your agreement to contract terms in the pile of papers that you were handed. If you trace through the entire pile of pieces of paper, you should find something saying that you agree to "all of the attached conditions", which is where you are supposed to say "Wait, what conditions?".