Hi, Chris here first time poster!

I am putting a small infloor hydronic system together to heat a small addition. This is to supplement my existing forced air gas system.

I am considering a Marathon hot water heater as the supply and the marathons come with a factory installed vacuum relief valve. My understanding of the vacuum relief is that it will let air into the system should a vacuum occur. Knowing that air in a hydronic system is not desireable should I remove the vacuum relief?

Is there any possible way a vacuum could be created in a closed loop system?

Regards,

Chris